An attic in a private house is an ideal solution for expanding a residential or useful utility area without completing the top floor. The arrangement of the attic in the attic space is an original and new exterior of the house, saving energy by reducing heat losses in the roof, and increasing living space. But the large size of the house is not a reason to start work on arranging the attic: you need to have a foundation with a sufficient margin of safety for the weight load, since the finished attic space will have to be thoroughly redone.
Features of the attic
The main thing that distinguishes the attic from ordinary rooms is that it has almost no walls in the usual sense, since the walls are a modified truss system constructed from many inclined roofing surfaces. Therefore, the design of the window will be very different - it should not interfere with natural light, and should take on the load in the form of precipitation and strong winds - the impact of weather conditions on a sloping roof is stronger than on the massive elements of the building.
Important! The SNiP regulation stipulates that the area of the window opening should not be less than 10% of the floor surface in the common room. Therefore, when dividing the attic space with partitions, it is advisable to also make a window in each newly formed room.
It is easier, cheaper and faster to mount an inclined window in the attic roof than to make a special vertical ledge under it, violating the design calculations. In any case, the window opening must be waterproofed or a window with reinforced glass and a reinforced metal-plastic profile should be ordered.
Benefits of installing an inclined roof window:
- A large stream of natural light, smoothing chiaroscuro;
- There is no need to radically alter the shape of the roof and change its relief;
- Simple installation, feasible for the owner himself.
The degree of illumination depends on the area of the opening, which is proportional to the angle of the roof. Therefore, the conclusion is obvious: the steeper the broken mansard roof, the wider and higher the window opening should be. The thickness of the metal-plastic profile should almost fit into the distance between the rafters, so that there is something to attach the window to without destroying the rafter system. If you order a wider window, you will have to make a reinforced jumper that fastens the rafters cut at the insertion point. If you need to install a wide window, you must first think about the option of installing two small adjacent windows so that the roof remains intact. 
When installing a dormer window (a vertical dormer window, it requires the frame to be moved outside the attic), the geometric shapes of the roof must be complicated by the installation of the upper and side valleys, and the laying or installation of the roofing also becomes more complicated. At the same time, it is much more difficult to remake a finished rafter system than to lay a new roof window in your individual one. Valleys must be carefully waterproofed, as their location and geometry relative to constant atmospheric influences make these places the most vulnerable to the penetration of moisture and cold. In regions with an average annual high precipitation, it is recommended to make snow retainers above the dormers. But the main advantage of the dormer - you can stand next to it in full growth - outweighs all the disadvantages that can be eliminated.
A window recessed into the roof is made if an exit to the balcony is organized through this window. In other cases, this is an unattractive option: poor natural lighting, unjustified complication of the roof geometry, high labor costs with a minimum of effect. 
The most affordable option is a window at the end of the attic - a cheap and practical solution that is fully implemented without outside help.
Attic truss system
In individual construction, a house with an attic is often built with a sloping roof, although this is an expensive solution. Broken mansard roofs, due to their design features, greatly increase the useful area of \u200b\u200bthe interior of the attic. With the same width of the foundation of the house and the floor, the rooms in such an attic will have a larger area due to ledges and niches than rooms under the roof of a conventional design. 
The standard design of a sloping roof allows you to lower the overhangs of the eaves much lower, not only making the exterior of the house very original - such overhangs protect the walls and foundation of the house from wind and moisture, directing atmospheric precipitation away from housing.
The more complex the sloping roof with your own hands, the stronger the dependence of the reliability of the structure on the materials from which the roof is made, on climatic conditions, on the thickness of the beams of the truss system and other factors. The classic do-it-yourself mansard roof, the drawings of which are given below, has a slope ratio of the lower slopes to the floor of 60 °, of the upper slopes - 30 °. 
SNiP stipulates a comfortable ceiling height in attic rooms - at least 2 m. Therefore, a scheme with a roof slope of 600 is fully justified, and structural reliability is ensured by thicker floor beams and rafters than when arranging a conventional gable roof.
In the classical construction of the attic, the force of the wind and the load from the weight of snow on the sides of the roof with a large slope are not taken into account. Snow will accumulate on the upper surface of the roof, made with a slope of 300-450. The greater the angle of inclination of the roof, the stronger the windage of the roof, therefore, in climates with strong winds, it is necessary to build roofs with a small slope, and this is a problem for arranging the attic - the area of \u200b\u200bthe house in such conditions should be quite large.
Broken roof schemes
The sloping roof frame is constructed from pine lumber of the first or second grade. For calculations, such parameters as the cross-section of timber and batten boards, the dimensions and weight of the roof from various building materials, snow and wind loads, and the rafter attachment step are regulated. 
The design of the roof with a hanging truss system is justified if at the base of the triangle (in the upper figure) there is a size ≤ 4.5 m - this determines the width of the attic. If the width is greater, then layered rafters are equipped, which are mounted on the wall.
How to calculate a broken type roof
The step between the rafters is often determined by the width of the insulation - this solution allows you to save on rolled materials, and the distance between the rafters is chosen 2-3 cm less than the width of the insulation material. For example, with a mineral wool slab width of 60 cm, the distance between adjacent posts should be 57-58 cm. 
The boards of the rafter legs are also calculated in width, based on the parameters of the insulation. To ventilate the layers of thermal insulation, it is necessary to provide a ventilation gap of 20-30 mm, otherwise the accumulated condensate will cause the wood to rot, and then damage the insulation. For the conditions of the middle strip, the thickness of the insulation can be no more than 230-250 mm, therefore the minimum width of the rafter legs is 230 mm with a board thickness of ≥ 50 mm. The greater the wind, temperature and snow loads in the region, the thicker the rafters should be made. 
Recommended: To save lumber, the insulation can be laid in two directions: along and across the rafters, making a thin and rare crate between the layers. With a minimum stone wool slab thickness of 100 mm, a 50 x 150 mm board can be used, leaving 50 mm for the ventilation gap.
Mansard roof installation
Mauerlat on the mansard roof is equipped with standard techniques - fastening the beam to the wall with knitting wire, anchors or studs. If the house is timber or log, then the upper crown of the log house, impregnated with an antiseptic and substances that increase the moisture resistance of wood, can serve as a Mauerlat. 
For a Mauerlat in a house made of cellular concrete, a monolithic reinforced grillage is poured on top of the walls, and the Mauerlat itself is attached to the rods concreted into the wall. For walls made of brick or reinforced concrete, such a concrete grillage is not necessary - the wall material itself is quite durable and will withstand any method of attaching the truss system. It will only be necessary to make a two-layer waterproofing around the entire perimeter of the house, and a Mauerlat beam with a section of 150 mm.
To assemble the elements of the truss structure, long nails are used - 150-200 mm. At the corners and at the intersections of the load-bearing walls with the internal partitions of the house, it is better to make bolted connections, or use double-sided threaded studs. Also, all intersections of roof elements are recommended to be additionally reinforced with metal plates-overlays. 
Installation of the attic truss system can be carried out in two solutions:
- Assembling the elements on the ground, lifting the finished structural units up. First of all, vertically corner elements are attached, which form future gables. The remaining elements of the roof structure are vertically inserted into the grooves made in the Mauerlat beam at a calculated distance and rigidly fixed. To give rigidity and correct geometry, you can temporarily fix the elements with spacers and braces, and after mounting the side beams, when the structure acquires the desired rigidity, the spacers can be removed;
- The second method is the sequential assembly of the mansard roof in place. It is more efficient and more convenient to work this way, because with a voluminous rafter system it will be problematic to lift the assembled roof manually - you will have to rent a crane. After assembling the structure, floor beams are laid, to which vertical beam racks are attached to the grooves, and temporary braces are installed to stiffen and make the system vertical. Then comes the assembly of the upper and side rafter legs, the jibs and struts are mounted in the same way.
The last stage is the installation of the upper beams, which are made according to the template, and the grooves for the rafters are immediately sawn into them. Since the mansard sloping roof does not have a ridge, slopes are mounted on the beam in the middle, which are designed to fix the upper triangle of the attic roof.
The attic design of the attic space allows not only to increase the living space of the house, but also to make the structure unusual and beautiful. Moreover, a building with this type of roof can be made in almost any style. A mansard-type roof, the variants of which can be very different, is found both in urban areas and in rural areas. Consider how to create such a design yourself, and find out what its features are.
Mansard roof - options
Such a roof has a special design of slopes, usually consisting of an upper sloping part and a steeper lower one. Thanks to this shape, a fairly spacious room appears inside, which can be used as an attic or even turn into a very cozy living room.
The history of mansards began in the 17th century, such a design of roofs was invented by the architect Francois Mansart - such a roof was named after his last name. But this Frenchman was far from being the first to implement the idea of economical use of the attic floor of the house. The mansard roof was first built by Pierre Lescaut, also a Frenchman who worked on the construction of such famous buildings as the Louvre and Notre Dame de Paris.
On a note! In the 19th century, poor people usually lived on the attic floors, but now this floor can appear in housing and is quite wealthy.
Now attics are quite often built during the construction of country houses or small two-story cottages, but the idea may well be implemented when creating other types of buildings. The attic has several advantages:
- building a house with an attic is cheaper than with two full floors and a roof;
- foundation costs during the construction of such a structure are also reduced;
- the attic can significantly increase the living space of any building;
- it gives the house an unusual and beautiful look;
- it is not difficult to build a structure, the work can be completed quite quickly;
- the attic is always associated with comfort;
- a house with an attic is warmer by reducing heat loss through the roof.
But lofts also have several disadvantages. This type of attic space has sloping ceilings, which results in a small wall height, which makes it difficult to choose furniture. Also, the roof must be well mounted so as not to leak and release heat from the house - you will have to spend money on good hydro- and heat-insulating materials. Yes, and building attics is still more difficult than, for example, the usual gable roof.
Design features
The attic is a universal element. It was used both for ordinary houses and for the construction of country houses, often this type of attic space was chosen even for the construction of palaces. Of course, it could decorate workshops, commercial buildings, etc. And despite the fact that different materials were used for its construction, different styles were chosen, the attic still remained an attic - it has certain design features.
So, this building can have a different geometric shape - triangular, broken, have symmetrical or, conversely, geometrically complex and non-standard slopes. It can be located both along the entire width of the building, and only on one side of it relative to the longitudinal axis.
Bar prices
On a note! If the roof is broken, then the lower part will have very steep slopes with an angle of inclination of about 60-70 degrees, and on the top slopes, on the contrary, will be gentle (about 15-30 degrees).
But whatever the attic, it will be located within the walls of the main building. Relative to the outer walls, the attic may be somewhat wider, but then it relies on the extensions of the ceilings. If the offset is large, then you will have to install additional supports (for example, columns, walls, etc.).
The height of the attic roof cannot be less than 2.5 m, otherwise it will not work to make a spacious room under it. Windows, which also need to be provided here, will be manufactured using special technologies using tempered durable glass and a reliable frame. They will cost several times more than usual. And load-bearing structures can be made of reinforced concrete, metal or wood. But in the case of the latter, it is important to carefully consider fire safety measures.
The mansard roof is a multilayer structure, which complicates installation. It can be insulated completely or only in the area of \u200b\u200bthe presence of a living room - where there is heating. But in any case, the design of the attic implies the presence of rafters, a ridge, directly roofing material, heat and waterproofing, and a vapor barrier layer. An interfloor overlap will act as a base under the roof.
Mansard roof rafters must have good bearing capacity. The cross section of the materials used will depend on the angle of the roof slope and cannot be less than 5x15 cm at a step of 100 cm. If the slope angle is 45 degrees, then a step of 140 cm is maintained.
Attention! In areas where it often snows and the amount of precipitation is high, it is recommended to install rafters with a step of no more than 80 cm.
If the attic is to be used as a living space, it is important to consider that in this case there is a risk of a large amount of condensate forming under the roof. Because of this, foci of mold may appear inside the structure, a fungus may develop, etc. The presence of a large amount of moisture will also negatively affect the insulating properties of the material. That is why it is important to follow all the rules for installing a mansard roof, and the heat-insulating material must be reliably protected from moisture, not only from the outside, but also from the inside, that is, a layer of vapor barrier material is also located on this side.
Important! Do not forget about the creation of roofing products that will allow air to circulate calmly inside the roof structure and help remove condensate.
Types of mansard roofs
There are 4 main types of mansard roofs, which differ from each other in design features. They can be divided into single-level and two-level. The former are the simplest in execution, usually combined with a broken or gable roof with a slope angle of 35-45 degrees. The second ones involve the arrangement of two rooms at different levels. Here a system of mixed supports is used.
On a note! When building an attic under a gable roof, the height of the walls can be no more than 1.5 m, followed by sloping ceilings. With a broken roof, the height of the ceiling along the perimeter near the walls is up to 2.5 m.
When building a house, you can stop at one of the types of attics - a single-level attic when arranging a gable roof, single-level with a broken roof, with remote consoles, or a two-level with a special mixed type of support.
Table. The main types of attics.
| Type of | Description |
|---|---|
| In this case, the attic has one level and is equipped under a conventional gable roof. The simplest option, in the design of which you can not use complex calculations. Precipitation with a gable simple roof comes off on its own, there is no need to equip any additional elements. |
| In this case, the attic also has one level, but the truss system is performed differently. Formed, as it were, four slopes of the roof. A much more spacious room can fit under it, but creating such a roof is more difficult. |
| Of the single-level attics, this is the most difficult option. Here the room under the roof is even more spacious. Usually in this case, the attic room is shifted to one of the edges of the house. This design allows you to make large vertical windows on one side. The main disadvantages are the complex shape, the complexity of construction. But on the other hand, under the edge of such an attic, you can make a functional canopy, where a terrace, garage or other extension can be located. |
| The most difficult option is the attic, since at least two rooms under the roof are located here, located at different levels. When designing a house, this design immediately enters into its structure. |
The mansard roof can also have a balcony. It is created on the principle of building a window. The main thing is that the bearing capacity of the walls allows you to equip it. By the way, columns can also support the balcony, but in this case it is built above the entrance.
Types of rafters for attics
Roof trusses can be of two types - and layered. You will have to choose between them depending on the method of attachment to the walls of the house. Hanging ones are simpler and are usually used for houses that do not have an average load-bearing wall. The rafters rest only on the main walls of the house, without intermediate supports. The width of the span between the walls cannot be large - usually it does not exceed 6 m. If the span is larger (over 9 m), then the arrangement of struts and attendants will be required.
Rafter rafters are usually used when creating houses with two spans, that is, those that have a load-bearing wall in the middle. In this case, the rafters have three points of support - directly this wall, as well as the main ones along the perimeter of the house.
Material for the manufacture of the truss system
Rafters can be made of metal, reinforced concrete or wood. Each material has its own advantages and disadvantages. Wooden rafters are environmentally friendly, they are easy to work with, easily adjusted to the desired size. But wooden structures are afraid of excess moisture and are prone to the formation of mold and fungus on them.
On a note! Before construction, wooden materials are recommended to be treated with protective compounds that will extend their service life.
Metal and reinforced concrete structures can not be covered with such compounds - fungus and mold do not appear on them. Due to this, they are considered more reliable and durable. But the main disadvantage is that, if necessary, it will be difficult to adjust them to the desired dimensions on the spot, and the slightest error in the calculations can lead to the roof being skewed. Also, a master working with reinforced concrete or metal rafters may face other difficulties - this is a large mass of products, which forces the use of special equipment even to lift elements.
Difficulties and features of the arrangement of the attic roof
When designing and building a mansard roof, a number of design features should be taken into account, on the basis of which a number of work rules are formed. For example, the Mauerlat must be fixed very securely with anchor bolts. It is he who will experience the maximum load, which means that he will hold the entire roof on himself. Anchors are additionally recommended to be walled up with a cement mixture if the main walls of the house are made of stone, brick and other similar materials.
It is also important to remember about the correct design and layers of the roof. For example, mansard roofs cannot be covered with metal roofing materials. They get very hot and it will be too hot on the top floor in summer, there can simply be no question of any comfort of living. It is not recommended to use roofing material as a waterproofing material - when heated, it begins to smell specifically. It is best to cover the mansard roof with slate or soft tiles. For thermal insulation, it is usually recommended to purchase mineral wool, which is laid with a waterproofing film on both sides.
A house with an attic is not only an additional living space, but also a respectable view of the entire building. Even if the room under the roof is made unheated and is used only in the summer, it still creates a powerful "air cushion" that helps to retain heat inside the entire capital building.
And about, then - read on our portal.
Attic project
When drawing up a scheme for building an attic, it is best to do this in different projections in order to see and understand the placement of all elements of the truss system. It is very important to correctly calculate the height of the roof ridge, since the size of the area under it will directly depend on it.
When drawing up a scheme-project for the construction of a mansard roof, you need to calculate the height of the ridge, the ceiling and the total area of \u200b\u200bthe room.
The minimum height from the floor to the ridge should be 2.5-2.7 m, if this distance is less, then the room is not an attic, it can only be called an attic. This parameter is set by the norms of SNIP.
In order for all elements to be drawn accurately and have the desired location in the overall system, it is necessary to start from a figure with right angles, that is, a rectangle or square - a section of the created attic room. Based on the sides (height and width of the future room), it will be almost impossible to make a mistake with the angles at which roof slopes are located, with the location of the ridge, rafters and all retaining elements. Determining these parameters, they must immediately be entered into the drawing.
First you need to find the middle of the width of the front wall. Starting from this point, the parameters of the height of the ridge, the future ceiling of the attic, the location of the rack-walls and the size of the cornice overhang are determined.
Due to the fact that each of the structures has a certain number of connecting nodes that have different configurations, it would be nice to draw each of these ligaments separately in order to understand their features of conjugation among themselves of all elements connecting at this point.
Any truss system consists of basic elements and additional ones, which may not be in every design. The main components of the attic roof are.
- Floor beams, which are the basis for the rest of the elements of the truss system. They are laid on the main walls of the building.
- Rafter leg, straight in a gable roof system or consisting of two sections - in a broken pattern. In this case, the upper rafter is called the ridge rafter, as it forms the highest point of the roof - and the rafters that form the walls of the attic are called side rafters.
- A ridge board or beam is an indispensable element for a gable roof, but is not always used when constructing a broken roof model.
- Mauerlat - a powerful bar, fixed to the main side walls of the building. Rafter legs are installed on this element.
- Racks are supporting elements necessary to strengthen a gable and broken structure. In the latter case, a ridge and side rafters are attached to it, and in the first case, the stand is a reliable support for a long rafter. In addition, the racks serve as a frame for insulation and sheathing of the attic walls.
- Diagonal braces or bevels additionally hold the posts or stringers and rafters together, making the structure more durable.
- Attic floor beams are used in all attic options - they connect the racks, and they are also the frame for the ceiling device.
- Interrafter runs are installed in a broken form of the roof for structural rigidity.
To be sure that the prepared project is developed correctly, you need to show it to a specialist. Only he can determine whether the attic parameters are correctly selected for the width and length of the walls of the building.
Video: professional mansard roof calculation using special software
Parameters of materials for the construction of a mansard roof
If the graphic project is ready, then, starting from the dimensions marked on it, you can calculate the amount of materials needed to build a mansard roof. Materials must be selected according to their characteristics, which must meet the requirements of fire and environmental safety. For wood, it is necessary to provide special treatment with fire retardants, which will reduce the combustibility of the material. So, for the construction you will need:
- Boards for rafter legs. Their cross section is selected according to the results of special calculations - this will be discussed in more detail below.
- A beam having a cross section of 100 × 150 or 150 × 200 mm - for floor beams, depending on the chosen truss system and the width between the bearing walls, as well as for purlins, diagonal legs or valleys - if they are provided for by the design.
- Beam with a section of 100 × 150 mm or 150 × 150 mm for laying Mauerlat.
- For racks, a beam of 100 × 100 or 150 × 150 mm is usually used.
- Unedged board for subflooring and some fasteners.
- Annealed steel wire with a diameter of 3-4 mm - for fastening together some parts.
- Nails, bolts, staples of various sizes, corners of various configurations and other fasteners.
- Metal sheet with a thickness of at least 1 mm - for cutting overlays.
- Lumber for battens and counter battens for roofing material - depending on the type of roofing chosen.
- - for thermal insulation of the roof.
- Waterproofing and vapor barrier membranes.
- Roofing material and fasteners for it.
What section are required rafters
Rafters are roofing elements that will perceive the main external loads, therefore, the requirements for their cross section are very special.
The size of the required lumber will depend on many parameters - on the step between the rafter legs, on the length of these legs between the support points, on the snow and wind load that falls on them.
The geometric parameters of the design of the truss system are easy to determine in the drawing. But with the rest of the parameters - you will have to refer to the reference material and carry out some calculations.
Snow load is not the same for different regions of our country. The figure below shows a map on which the entire territory of Russia is divided into zones according to the intensity of the snow load.
There are eight such zones in total (the last, eighth, is more likely to be extreme, and it can not be considered for the construction of a mansard roof).
Now you can accurately determine the snow load, which will depend on the angle of the roof slope. For this, there is the following formula:
S = Sg × μ
Sg- tabular value - see the map and the table attached to it
μ — correction factor depending on the steepness of the roof slope.
- If the slope angle is less 25° then μ=1.0
- With a steepness from 25 to 60 ° - μ=0.7
- If the roof is steeper than 60 °, then it is considered that the snow does not linger on it, and the snow load is not taken into account at all.
It is characteristic that if the mansard roof has a broken structure, then for its different sections the load can have different values.
The angle of the roof slope can always be determined either by a protractor - according to the drawing, or by a simple ratio of the height and base of the triangle (usually - half the width of the span):
The wind load also mainly depends on the region of construction of the building and on the characteristics of its environment and roof height.
And again, for the calculation, the initial data on the map and the table attached to it are first determined:
The calculation for a particular building will be carried out according to the formula:
Wp = W × k × c
W- tabular value, depending on the region
k- coefficient taking into account the height of the building and its location (see table)
The following zones are indicated in the table with letters:
- zone A - open areas, steppes, forest-steppes, deserts, tundra or forest-tundra, open to the winds of the coast of the seas, large lakes and reservoirs.
- zone B - urban areas, wooded areas, areas with frequent obstacles to the wind, relief or artificial, at least 10 meters high.
- zone AT- dense urban development with an average height of buildings above 25 meters.
With- coefficient depending on the predominant wind direction (wind rose of the region) and on the angle of inclination of the roof slopes.
With this coefficient, the situation is somewhat more complicated, since the wind can have a double effect on the roof slopes. So, it has a direct, overturning effect directly on the roof slopes. But at small angles, the aerodynamic effect of the wind takes on special significance - it tries to raise the slope plane due to the emerging lifting forces.
In the drawings, diagrams and tables attached to them, the sections of the roof that are subject to maximum wind loads are indicated, and the corresponding coefficients for calculation are indicated.
It is characteristic that at slope angles up to 30 degrees (and this is quite possible in the section of ridge rafters), the coefficients are indicated both with a plus sign and negative, that is, directed upwards. They somewhat extinguish the frontal wind load (this is taken into account in the calculations), and in order to level the effect of lifting forces, it will be necessary to carefully fix the truss system and roofing material in this area using additional connections, for example, using annealed steel wire.
After the wind and snow loads are calculated, they can be summed up, and, taking into account the design features of the system being created, determine the cross section of the boards for the rafters.
Please note that the data are given for the most commonly used coniferous material (pine, spruce, cedar or larch). The table shows the maximum length of the rafters between the support points, the cross section of the board depending on the grade of the material, and the step between the rafters.
The value of the total load is indicated in kPa (Kilopascals). It is not difficult to bring this value into more familiar kilograms per square meter. With quite acceptable rounding, you can accept: 1 kPa ≈ 100 kg/m².
The dimensions of the board along its section are rounded up to the standard sizes of sawn timber.
| rafter section (mm) | Distance between adjacent rafters (mm) | ||||||
|---|---|---|---|---|---|---|---|
| 300 | 600 | 900 | 300 | 600 | 900 | ||
| 1.0 kPa | 1.5 kPa | ||||||
| higher | 40×89 | 3.22 | 2.92 | 2.55 | 2.81 | 2.55 | 2.23 |
| 40×140 | 5.06 | 4.60 | 4.02 | 4.42 | 4.02 | 3.54 | |
| 50×184 | 6.65 | 6.05 | 5.28 | 5.81 | 5.28 | 4.61 | |
| 50×235 | 8.50 | 7.72 | 6.74 | 7.42 | 6.74 | 5.89 | |
| 50×286 | 10.34 | 9.40 | 8.21 | 9.03 | 8.21 | 7.17 | |
| 1 or 2 | 40×89 | 3.11 | 2.83 | 2.47 | 2.72 | 2.47 | 2.16 |
| 40×140 | 4.90 | 4.45 | 3.89 | 4.28 | 3.89 | 3.40 | |
| 50×184 | 6.44 | 5.85 | 5.11 | 5.62 | 5.11 | 4.41 | |
| 50×235 | 8.22 | 7.47 | 6.50 | 7.18 | 6.52 | 5.39 | |
| 50×286 | 10.00 | 9.06 | 7.40 | 8.74 | 7.66 | 6.25 | |
| 3 | 40×89 | 3.06 | 2.78 | 2.31 | 2.67 | 2.39 | 1.95 |
| 40×140 | 4.67 | 4.04 | 3.30 | 3.95 | 3.42 | 2.79 | |
| 50×184 | 5.68 | 4.92 | 4.02 | 4.80 | 4.16 | 3.40 | |
| 50×235 | 6.95 | 6.02 | 4.91 | 5.87 | 5.08 | 4.15 | |
| 50×286 | 8.06 | 6.98 | 6.70 | 6.81 | 5.90 | 4.82 | |
| total snow and wind load | 2.0 kPa | 2.5 kPa | |||||
| higher | 40×89 | 4.02 | 3.65 | 3.19 | 3.73 | 3.39 | 2.96 |
| 40×140 | 5.28 | 4.80 | 4.19 | 4.90 | 4.45 | 3.89 | |
| 50×184 | 6.74 | 6.13 | 5.35 | 6.26 | 5.69 | 4.97 | |
| 50×235 | 8.21 | 7.46 | 6.52 | 7.62 | 6.92 | 5.90 | |
| 50×286 | 2.47 | 2.24 | 1.96 | 2.29 | 2.08 | 1.82 | |
| 1 or 2 | 40×89 | 3.89 | 3.53 | 3.08 | 3.61 | 3.28 | 2.86 |
| 40×140 | 5.11 | 4.64 | 3.89 | 4.74 | 4.31 | 3.52 | |
| 50×184 | 6.52 | 5.82 | 4.75 | 6.06 | 5.27 | 4.30 | |
| 50×235 | 7.80 | 6.76 | 5.52 | 7.06 | 6.11 | 4.99 | |
| 50×286 | 2.43 | 2.11 | 1.72 | 2.21 | 1.91 | 1.56 | |
| 3 | 40×89 | 3.48 | 3.01 | 2.46 | 3.15 | 2.73 | 2.23 |
| 40×140 | 4.23 | 3.67 | 2.99 | 3.83 | 3.32 | 2.71 | |
| 50×184 | 5.18 | 4.48 | 3.66 | 4.68 | 4.06 | 3.31 | |
| 50×235 | 6.01 | 5.20 | 4.25 | 5.43 | 4.71 | 3.84 | |
| 50×286 | 6.52 | 5.82 | 4.75 | 6.06 | 5.27 | 4.30 | |
Tools
Naturally, during work, one cannot do without tools, the list of which includes:
- Electric drill, screwdriver.
- Building level and plumb line, tape measure, square.
- Axe, chisel, chisel, hammer
- Circular saw, jigsaw, hacksaw.
- Carpentry knife.
Installation will be accelerated if the tools for work are of high quality, and the work is carried out with competent mentors, with assistants, carefully and in stages.
Installation steps
It is necessary to strictly observe the sequence of work - only under this condition the design will turn out to be reliable and durable.
Mauerlat mount
The installation of any truss system begins with fixing a powerful supporting structure at the end of the side walls of the structure. timber - Mauerlat on which it will be convenient to install rafter legs. Mauerlat is made from a high-quality bar with a cross section of at least 100 × 150 mm. It must be laid on the roofing material waterproofing laid along the upper end of the wall (regardless of the material).
Due to the Mauerlat, the load will be evenly distributed along the walls and transferred to the foundation of the building.
The Mauerlat is fixed to the wall with metal studs, which are pre-embedded in a concrete belt or a crown running along the upper edge of the wall, or with anchor bolts with a diameter of 12 mm. They must go deep into the wall by at least 150 — 170 mm. If the Mauerlat is installed on a wooden wall, then the bars are attached to it with the help of wooden dowels.
Installation of the truss structure
- Installation of the truss system begins with the installation of floor beams. They can be mounted on the Mauerlat from above, if the beams are planned to be taken out of the perimeter of the building and thereby increase the attic area. In this design, the rafter legs are fixed to the floor beams.
Floor beams fixed on top of the Mauerlat (Fig. A) - Otherwise, they may fit into waterproofed walls and fastened with corners or staples to the inner edge of the Mauerlat. This option is used when the rafter legs are planned to be fixed directly to the Mauerlat.
Another option - only rafter legs are attached to the Mauerlat - Next, you need to find the middle of the floor beam, since this mark will become a guideline for determining the location of the support posts and the ridge.
- Racks should be located at the same distance from the marked middle of the floor beam. In the future, they will begin to determine the location of the walls of the attic room, that is, its width.
- Bars for racks should have a cross section equal to the size of the floor beams. Construction sites are attached to the beams with the help of special corners and wooden linings. However, to begin with, they are first baited with nails, then carefully leveled with the help of a building level and a plumb line, and only then they are fixed thoroughly, with the expectation of future loads.
- When the first pair of racks is installed, they are fastened together from above with a bar, which is called a puff. This puff is also connected to the racks using special metal corners.
- After fixing the puff, you get a U-shaped design. Layered rafters are installed on it on the sides, which are attached to the floor beam with their second end or are laid on the Mauerlat.
- A special notch (groove) is cut out on the installed supports for the timber or in the rafters. With its use the rafters are tightly installed on the mauerlat beam, and fastened with metal brackets.
- For structural rigidity, struts can be additionally installed from the base of the rack to the middle of the installed side rafter. If this seems not enough, and saving material is not in the foreground, then you can strengthen the overall design with additional racks and contractions (they are indicated in the drawing in Fig. A by translucent lines).
- Further, the middle is calculated on the puff - a headstock will be attached to this place, supporting the ridge connection of the upper hanging subsystem of the rafters.
- The next step is to install ridge rafters, which can be fastened together with different connections - this can be a metal lining or powerful bolts with metal plates or washers.
- After their installation, a headstock is attached to the ridge and the middle of the puff.
- Having completed work on one part of the truss system, you need to make all the rest according to the same principle. The distance between adjacent rafters in such a system should be no more than 900 — 950 mm, but the interval of 600 mm will probably still be optimal - this will give both the necessary rigidity and stability of the structure, and will be convenient for insulation using standard mineral wool mats. True, this makes the structure heavier and requires more materials.
- First, the side parts of the complete system are installed, and then the intermediate ones. Between themselves, they are connected by runs, which are installed between the upper ends of the racks and act as spacers. Thus, a rigid structure of the attic rafters will be obtained, in which the frame for wall cladding will already be ready.
Prices for various types of fasteners for rafters
Fasteners for rafters
Mansard roof waterproofing
When the truss system is built, you can proceed to finishing it and their accompanying materials.
- The first coating to be fixed immediately on top of the rafters will be waterproofing and windproof film. it is attached to the rafters with staples and a stapler, starting from the eaves. Cloths are overlapped by 150 — 200 mm, and then the joints are glued with waterproof tape.
- On top of the waterproofing, a counter-lattice is stuffed onto the rafters, which will more reliably fix the film on the surface and create the necessary ventilation distance between the windproof and roofing material. The counter-lattice is usually made of boards with a width of 100 — 150 mm and 50 thick — 70 mm.
- A crate is fixed perpendicular to the counter-lattice, on which the roofing material will then be laid. The step between the rails must be calculated depending on the type and size of the sheet roofing material, taking into account the overlap required for it.
- If a soft roof is chosen, then plywood sheets are most often fixed to the counter-lattice.
Roofing installation
Roofing material is fixed on the prepared crate or plywood. Its installation usually starts from the roof eaves and runs in order, from one of the edges - depending on the type of roof. Roofing sheets are mounted with an overlap. If a metal profile or metal tile is used for coating, then such material is fixed with special self-tapping screws with elastic gaskets. Fasteners are usually matched in color to the roofing material.
The most difficult thing in covering a mansard sloping roof is the transition from layered side rafters to hanging ridge rafters. There may be certain difficulties in the event that ledges are provided on the roof for roofing over balconies or windows.
In addition, if a chimney pipe enters the roof, it requires a separate opening inside the rafter system and the insulation layer, and on the roof, a reliable waterproofing device around the pipe.
How and what is better to cover the roof, you can find out in detail on our portal, there is a whole section in which you can find answers to many questions, including recommendations for reliable insulation of the attic room.
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Decking
Video: a detailed video tutorial on building a mansard roof
It should be noted that the work on the construction of any roof, and even more so complex as an attic, is not only responsible, but also quite dangerous, it requires special, increased security measures. If there is no experience in carrying out such construction processes, then it is better to entrust their implementation to professionals or to perform all actions under the supervision of an experienced craftsman, and with the utmost care and accuracy.
Probably the best way to increase the usable area of your own house is to replace the gable roof of the house with a mansard. In this way, one, two or even three additional rooms can be purchased without carving out additional space on the site and without getting involved in the very laborious processes of pouring a new foundation and erecting walls. And in order to find out how to make the attic correctly, you need to consider all the stages of its arrangement, starting with calculations and ending with the roofing of the roof and finishing the resulting additional premises.
In order for all work to be successful, first of all, you need to make sure that the existing walls (if the add-on will be built in the old house) are able to withstand the additional load. It will depend on this factor whether it is worth starting such a construction site, and if so, on which design of the mansard roof it would be better to stop.
It should be noted that the load on the load-bearing walls will increase significantly - due to a larger number of rafters, due to the mass of interior decoration of walls and floors, windows and doors, insulation systems, as well as all elements of the interior filling of attic rooms. All these factors indicate that you need to start with the choice of the optimal attic design, with calculations, drafting and drawings of the future superstructure.
Types of attic superstructures
According to current building codes, an attic is considered to be a room under a roof that has a height from ceiling to ridge of at least 2500 mm. If this parameter is less than the specified limit, then the room is considered an ordinary attic.
- If the vertical racks that determine the height of the walls of the room are 1500 mm in size, then the attic space can be considered a full-fledged floor.
- A semi-mansard is an attic room in which there are no vertical racks, or if they have a height of 500 to 700 mm.
At the heart of any roof structure are always triangles with their “rigid” structure. There are several types of attic superstructures, but the most popular of them are high gable and broken structures. Their popularity can be explained by simpler calculations, relatively simple installation work and ease of use. In third place, after gable and broken structures, one can name a shed version of the roof, which is also sometimes used to equip the attic. Unfortunately, this type of superstructure can not be used in every house design, since it requires not only the reconstruction of the roof, but also raising the height of already built walls, which significantly increases the load on them and on the foundation.
If a new house is being built, and a second floor is planned in the form of an attic, then a shed roof option is well suited for this purpose. In addition, it will help save on roofing material.
More complex structures - domed, four-pitched, as well as with various protrusions-consoles arranged in the roof slopes (single-level and multi-level), are used extremely rarely and only in exclusive projects, as they have a complex design both in engineering calculations and in installation.
The figure below the numbers shows:
1 - Gable attic.
2 - Broken attic
3 - Single-level console attic
4 - Multi-level attic.
Gable attic
attic space under d with a wuska roof, which is arranged at an angle between the slopes of 80 ÷ 90 degrees on the ridge, it may well be converted into an attic. To create full-fledged living quarters under it, it will be necessary to carry out a number of necessary reconstructions, for example, very often it is not possible without strengthening the attic floor. All these alterations and plus to this - the necessary insulation will certainly “eat up” a significant part of the usable space under the roof, so you should not expect that the rooms in such an attic will be spacious and with high ceilings.
Of course, if the dimensions (length and width) of the house are large enough, and the roof has a significant angle of inclination (45 degrees or even higher), then after the alterations it will be possible to count on a relatively spacious attic room.
broken roof
A room under a sloping mansard roof will be much more spacious and with a fairly high ceiling. Such an attic can be easily divided into two separate rooms.
The interior of the attic, made according to the "broken" type The sloping roof has four planes of slopes. They are located at different angles - the upper slopes are called ridge, and the lower ones are lateral. They, for the most part, play the role of walls.
This type of mansard roof is somewhat more difficult to design and install, but the result will please you with spacious rooms and a respectable appearance of the house.
One-level console attic
This type of attic has an even more complex design than the previous one, as it implies a displacement of the attic space to one side or the other.
Using this version of the attic device, you can get spacious rooms, much larger in area than under a gable roof.
The design of a single-level mansard roof can repeat not only a gable, but also a shed version - this will depend on how much it is supposed to take the console out of the attic and raise its ceiling.
Layered add-on
A multi-level structure is the most difficult to design and install. In its development and construction, the help of qualified specialists will definitely be needed. The supports for the levels of the attic rooms are different truss systems and ceilings, which are combined with the main one. A multi-level system involves the location of rooms at different levels of the attic, which is why the consoles should be located that way.
Having chosen the most desirable type of attic, it is necessary to determine whether it is possible to arrange it on the old walls of the house, or whether they will have to be strengthened. Therefore, it is necessary to carry out accurate calculations and draw up a project.
Roof truss basics
Most roofs, and the attic in this matter is no exception, have one of two types of truss system, or a combination of them. Each of these varieties has its own characteristics, which depend on the location of the load-bearing walls of the building.
Hanging system
The hanging truss system is determined by the fact that it is supported only by two external capital walls located along the length of the building, in which there are no internal capital partitions.
Such a system is used provided that the distance between the main supports is no more than 13 ÷ 14 meters. In any case, this design gives a fairly large load on the walls and foundation of the building.
To reduce the loads in this system, various support structures are used. elements - crossbars, grandmas, struts, puffs, racks and other details.
For example, headstocks, as it were, suspend the entire system to the ridge beam with the help of a puff, and struts pull the overlapping beams to the rafter legs.
For the attic floor in this system, it is necessary to use thick bars, logs or boards that are installed on the edge. Their thickness can be determined from the table given in this publication, based on the distance between the support points.
In order for the floor to be reliable and durable when using a hanging system, you need to carry out accurate calculations, and if it is difficult to do it yourself, then it is better
Layered construction
The layered system is distinguished by the fact that it has supports not only on external main walls, but also on internal partitions, which have a foundation under them.
Therefore, starting the construction of a house in which an attic is planned, you need to think in advance about the location of the internal capital partitions.
For a house with an attic, a layered system is the best option, since the beams overlapping the house will be firmly and securely fixed to the walls and partitions.
When erecting a broken attic roof structure, you can use a combined version of the truss system, that is, use elements of both a hanging and a layered system.
Attic design
When drawing up a project for the construction of any type of attic, it is recommended to consider it in different projections in order to visually determine the location of all supporting elements. Calculating all the parameters of the attic, they must be immediately included in the project.
Based on the calculations made, the places and methods of installation of all structural elements of the truss system are determined. The calculation is also necessary to accurately determine the materials needed for the construction of the attic and their parameters.
Structural elements
Any of the wooden structures of the mansard roof consists of certain elements that are interconnected by connecting nodes that have different configurations. To better understand the design of these connections, it is recommended to draw each of them, and when carrying out installation work, be sure to have this drawing on hand.
The design of a broken mansard roof includes the following components of the system:
- Mauerlat - element, made of a wooden beam and laid on the main walls of the building in its length. It serves to evenly distribute the load from the structure of the truss system to the wall and foundation. Rafter legs are installed and fixed on the Mauerlat. This element is mounted both in a gable and in a broken structure of the attic roof.
- Floor beams, which are laid on the main walls of the building and are the basis for the future floor of the attic and the ceiling of the first floor, as well as for the installation of the entire truss system.
- The rafter leg consists of one straight element - bar or boards in a gable type of roof, or from two parts - in a broken structure. In a broken mansard roof, the upper part fixed to the ridge is called the ridge, and the lower part, which forms the walls of the attic, is called the side. Obviously, the side leg will be installed on a layered basis, while the upper ridge rafter - usually becomes hanging
- For the ridge, a beam or board of a certain thickness is used. Sometimes they do without it, connecting the upper ridge parts of the rafter legs together, which form the ridge.
- Racks are the supporting elements of the system. They support the rafter legs and take some of the load off the walls and foundation of the building. Racks in the future will become a crate for the walls, which will be installed in the process of finishing the attic.
- Bevels or other elements installed diagonally are additional supports that hold the rafters and retaining beams together, making the system more reliable.
- Between the rafter legs for rigidity, bars are installed, called inter-rafter runs - they also give the system rigidity.
Carrying out basic attic calculations
It is quite difficult to develop a mansard roof project on your own, since this process requires certain knowledge and skills in designing and carrying out specific architectural calculations. If you make mistakes at the same time, the design of the attic will be unreliable, and besides, with its weight it can damage the walls and foundation of the building.
Everything must be taken into account in the calculations - from the beginning of construction to the finishing of the premises. However, if a not too complicated design is conceived, then you can try to cope on your own.
Skate Height Calculation
The size usable area attic room depends on the height of the roof ridge, and the latter is determined by the selected slope of the slopes - the smaller this angle, the lower the ceiling and, accordingly, less effective area attic space.
H=L×tgα
H- the height of the skate;
L- ½ the width of the building (if we are talking about a gable symmetrical roof);
α - the angle of inclination of the slope of the truss system.
Scheme - for clarity As an example, you can substitute the above data into the formula:
Building size 8×10 m, slope angle 30°, tangent 30°= 0.58
H \u003d 8/2 × 0.58 \u003d 2.32 m
The height of the skate will be 2,32 m.
In great detail, with all possible nuances and necessary reference tables, the process and all other parameters associated with it are described from a separate publication dedicated to this particular issue.
The area of the interior space of the attic
The technique used to determine the area of the attic space will make it possible to calculate the amount of material needed for the construction of the truss system, for insulation and decoration. Especially accurate calculations are important if the attic will be used to equip additional living rooms, as they require special design.
Usually the entire area of \u200b\u200bthe room under the roof is calculated, that is, both useful and the so-called "deaf". The living space is limited to the installed racks, which will be the basis for the installation and finishing material of the walls. The zone behind them is considered deaf, that is, most often not used.
The total area is calculated quite simply: the width of the overhangs on both sides is added to the width of the building. The resulting amount is multiplied by the length of the building.
It is also easy to find the area of \u200b\u200bliving space: for this you need to measure the width of the attic space between the racks installed under one and the other slope of the roof, and multiply the resulting parameter by the length of the attic from gable to gable.
Roofing area
To determine in advance the amount of roofing material, it is necessary to calculate the total area of \u200b\u200bthe roof slopes.
If a decision is made to install a broken or even more complex structure, it is necessary to calculate the area of \u200b\u200ball sections of the roof. To do this, you need to break it into separate geometric shapes, and then calculate the area of \u200b\u200beach of them and add the results.
For those who do not firmly remember the formulas for calculating the areas of flat figures, a "cheat sheet" scheme is given.
Shed roof area
If the attic roof is pitched, then its area can be calculated using the formula: Sabcd = Lcd × Lbd.
The area of one slope - there is nothing easier Pay attention to the drawing. When calculating, not only the length and width of the roof structure of the slope are taken into account - we must not forget about the cornice overhangs from all sides.
gable roof
With a symmetrical arrangement of roof slopes, for calculating a gable roof, it remains only to multiply the value obtained above by two.
For example, take the same example as discussed above. The size of the building is 10×8 m. The angle of the slope is 30 °, the height of the ridge H = 2.32 m. It is easy to determine the length of the rafter - S
S = H / sin α = 2.32 / 0.5 = 4.64 m
We accept cornice overhang 0,7 m, gable overhang 0,7 m. According to the shed roof formula, the area of \u200b\u200bone slope is calculated.
(10 + 2 × 0.7) × (4.64 + 0.7) = 60.88 m²
Then, to get the total area of the two slopes, the resulting result is multiplied by two.
Q = 121.76 m²
This technique is designed to calculate the continuous surface of slopes, excluding windows, ventilation channels and a chimney.
If the roof has a very complex structure, then it is better not to take risks and still seek the help of professionals who will make the necessary calculations using special computer applications.
When using slate, soft roofing, other profile materials, you can use a simplified calculation formula.
Starting from the drawing:
So, the following formula is applicable for calculation:
Q\u003d K × (B + 2A) × (L + 2C)
Q- the required amount of roofing;
AT — the width of the building (along the gable wall);
BUT- the width of the planned eaves of the roof;
L- total length of the building;
C- the width of the side overhangs of the roof.
To is a coefficient that takes into account the angle of inclination of the slope with respect to the horizon (α). By and large, it is a trigonometric function of secant (sec), equal to the reciprocal of cosα.
In order not to delve into the theory, it is easier to give a coefficient table To in absolute, that is, numerical measurement:
| Tilt angle, degrees | K factor | Tilt angle, degrees | K factor | Tilt angle, degrees | K factor | Tilt angle, degrees | K factor |
|---|---|---|---|---|---|---|---|
| 1 | 1.0002 | 18 | 1.0515 | 36 | 1.2361 | 53 | 1.6616 |
| 2 | 1.0006 | 19 | 1.0576 | 37 | 1.2521 | 54 | 1.7013 |
| 3 | 1.0014 | 20 | 1.0642 | 38 | 1.2690 | 55 | 1.7434 |
| 4 | 1.0024 | 21 | 1.0711 | 39 | 1.2868 | 56 | 1.7883 |
| 5 | 1.0038 | 22 | 1.0785 | 40 | 1.3054 | 57 | 1.8361 |
| 6 | 1.0055 | 23 | 1.0864 | 41 | 1.3250 | 58 | 1.8871 |
| 7 | 1.0075 | 24 | 1.0946 | 42 | 1.3456 | 59 | 1.9416 |
| 8 | 1.0098 | 25 | 1.1034 | 43 | 1.3673 | 60 | 2.0000 |
| 9 | 1.0125 | 26 | 1.1126 | 44 | 1.3902 | 61 | 2.0627 |
| 10 | 1.0154 | 27 | 1.1223 | 45 | 1.4142 | 62 | 2.1301 |
| 11 | 1.0187 | 28 | 1.1326 | 46 | 1.4396 | 63 | 2.2027 |
| 12 | 1.0223 | 29 | 1.1434 | 47 | 1.4663 | 64 | 2.2812 |
| 13 | 1.0263 | 30 | 1.1547 | 48 | 1.4945 | 65 | 2.3662 |
| 14 | 1.0306 | 31 | 1.1666 | 49 | 1.5243 | 66 | 2.4586 |
| 15 | 1.0353 | 32 | 1.1792 | 50 | 1.5557 | 67 | 2.5593 |
| 16 | 1.0403 | 33 | 1.1924 | 51 | 1.5890 | 68 | 2.6695 |
| 17 | 1.0457 | 34 | 1.2062 | 52 | 1.6243 | 69 | 2.7904 |
| 35 | 1.2208 | 70 | 2.9238 |
Let's go back to our example:
Q= 1.1547 × (8 + 2 × 0.7) × (10+2 × 0.7) = 123.74 m²
Taking into account overlaps slate sheets - it turns out almost the same as in calculations carried out by a different method. Of course, on the advice of experienced builders, another 10 ÷ 15 %
(The figure shows a gable roof, however, the formula is fully suitable for calculations with the required level of accuracy for single-pitched or hip roofs. True, with a caveat - at the hip roof, the steepness of the main and side slopes must match. If not, then the calculation is carried out for each pairs of rays separately, and then the value is summed).
Total weight from truss system and roofing
It is equally important to correctly choose the optimal material for roofing and correctly make a crate for it. This calculation is carried out taking into account the length of the rafters and the angle of their slope.
The crate for roofing material can be sparse, mixed or solid. For example, a metal tile, corrugated board or slate is fixed to a sparse crate, and a soft roof - only to a solid one.
When choosing a roof, you need to get information about its operational characteristics. It is from them that the durability and reliability of the roof structure will depend. Roofing material must also be selected taking into account the specific region and its climatic conditions, especially factors such as temperature changes and strong winds.
An important factor is the weight of the roofing, especially if the mansard roof is installed on old walls. Therefore, you should estimate the weight of the roof in advance and find out how much the load on the building structure will increase, and whether it will be acceptable.
| Roofing material for mansard roof | Roof pitch | Material weight kg / m² |
|---|---|---|
| Asbestos cement slate sheets with medium profile | 1:10 to 1:2 | 11 |
| Slate with reinforced profile | 1:5 to 1:1 | 13 |
| bituminous tiles | From 1:10 and more | 6 - 8 |
| Soft roofing, taking into account the continuous lathing | From 1:10 and more | 9 - 15 |
| Galvanized metal sheets with single seam | From 1:4 and more | 3 - 6,5 |
| With double folds | From 1:5 and more | 3 - 6,5 |
| Ceramic tiles | 1:5 to 1:0.5 | 50 - 60 |
| Cement-sand tiles | 1:5 to 1:0.5 | 45 - 70 |
| metal tile | From 1:5 and more | 5 - 7 |
| Ondulin | From 1:10 and more | 3 - 3,5 |
Most often, soft roofing or ondulin is used to cover attics, since these materials are one of those that have the lightest weight and are easy to install.
For example, you can calculate the weight of 1 square meter of roofing, where ondulin is used for coating, taking into account the crate and insulation - sprayed polyurethane foam. To do this, you need to find the sum of the weight of each of the materials and multiply by a factor of 1.1 (this factor takes into account the overlap on adjacent sheets of roofing material).
- The weight from a flat crate, 20 mm thick (plywood or OSB) is 14 kg / m².
- Insulation - polyurethane foam, 100 mm thick, has an average weight of 3 kg / m²
- The average weight of ondulin is 3.3 kg / m²
We get in total:
(14 + 3 + 3.3) × 1.1=22.3kg /m²
To calculate the total weight load of the roof on the walls, you need to multiply the weight of one square meter by the area of \u200b\u200bthe entire coating. In our example, this will work:
M = 123.74 × 22.3 = 2751.82 kg.
A lot - almost 3 tons gives only a very light roofing with a crate and also a very light type of insulation.
But that's not all! The roof is affected by snow loads in the winter, plus wind pressure, all year round. These parameters are also necessarily taken into account when calculating the necessary wooden structural elements of the truss system and floor beams, and when taking into account the total load of the roof structure on the walls and foundation of the building.
- Then, the whole system is closed with a vapor barrier film, which is fixed on the logs with brackets.
- Boards or plywood sheets can be laid on top of it.
- A decorative coating is laid on them - it can be linoleum, laminate, parquet board and other materials.
Additional insulation can be created by laying an electric cable or infrared warm floor under the decorative coating. It is better to read about these possibilities separately in the article devoted to
- If the floor is mounted on floor beams, you will have to work from the side of the first floor.
- From the side of the lower room, boards are mounted on the floor beams. It is desirable that they be even, you can even use a floorboard for the subfloor.
- After that, a vapor barrier film is laid on these boards from the side of the attic, which will cover not only the subfloor, but also the floor beams.
- On top of it, another layer of vapor barrier is laid and attached to the beams.
- Then, logs are fixed to this coating perpendicular to the beams.
- Another layer of insulation is mounted between the lags, for it it is better to choose mineral wool, since, when straightened, it is tightly installed between the bars, leaving no voids.
- Then it should also be covered with vapor barrier material.
If it is decided to cover the floor with one of the decorative coatings, then plywood sheets are laid on top of the log, and then laminate, linoleum or other materials are laid on them. Again, nothing prevents in this case from using, for example, film floor heating.
Installation of insulation on the walls and ceiling of the attic
Having finished the installation of the floor, you can proceed to the installation of insulation on the walls.
- If material in mats is chosen for this process, then before laying it, sheets of vapor barrier material are fixed on the rafters.
It is fixed in such a way as to close the entire space and deepen it between the rafters.
If the vapor barrier is fixed on the other side of the rafters, then the mats will independently hold between two wooden surfaces.
- If one of the is selected, then it is not necessary to fix the vapor barrier film under it. It will be enough waterproofing, which is laid on the rafters outside the structure.
Spraying polyurethane foam - quickly and efficiently, but requires special equipment and work skills To use this insulation technology, you must have special technological equipment, or you will have to invite a specialist who will do the work in one day. It is not easy to carry out this operation on your own without experience - in order to do the work without harming your health, you need to know the process technology and have the necessary protective devices.
After carrying out insulation work, wall cladding is carried out.
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insulation
Attic wall decoration
Before you start finishing the walls, you need to resolve the issue of electrical wiring, the cable of which must be well insulated with double-layer corrugated pipes.
After the wiring of the electrical cable is done, you can safely proceed with the installation of the finishing material.
For decoration, they usually use wooden lining, drywall or plywood with a beautiful textured pattern.
For any of these materials, it is desirable to make a crate of slats on the rafter legs and vertical racks with a section size of approximately 20 × 70 mm. These guides are fixed in increments of 500 ÷ 600 mm. In addition to the fact that the crate of the slats becomes the basis for fixing the finish, it also forms a ventilation gap between the finishing material and the vapor barrier.
- made quite simply. It leaves walls smooth and neat, ready for painting, traditional wallpapering or even liquid wallpapering.
Therefore, drywall finishing should be chosen by those homeowners who like to often change the interior design of the premises.
- Clapboard wall decoration is a longer and more laborious process than. For such a sheathing, a crate with the above parameters is also perfect. The only thing to think about is the direction of the lining boards, that is, it should be located vertically with the horizontal orientation of the crate and vice versa.
If desired, after installation, the wood can be varnished with a water-based varnish or give it a deeper color using a stain.
Wood is an amazing material that can create a special atmosphere in the room with the aroma of the forest, which has a positive effect on the structure and well-being of the residents. That is why natural lining is very often chosen for flooring, walls and attic ceilings.
Video: insulation of the attic room and finishing it with clapboard
- You can come up with a beautiful plywood finish. But that's only if it will not be covered with paint on top, then you need to choose a quality material that has a beautiful natural pattern. Plywood is mounted much faster than lining, and makes the walls even, covering large surfaces at once.
This material can be covered with varnish, paint or any kind of wallpaper, but you can leave the walls in their natural state only by carefully cleaning possible defects in the form of protruding splinters or burrs.
The construction of an attic is a rather laborious and complex process that requires high experience in the construction craft. If there is no one to understand about the above technological operations, then you should not take it on your own - it is better to invite professional masters to perform the work. They will save you from unnecessary problems and build an attic according to the project conceived by the owner of the house.
Video: an example of the construction and decoration of the attic
A house with an attic is not just an additional living space, but also a presentable view of the entire building. Even if the room under the roof is not heated and is used only in summer, it still has a powerful “air cushion” that helps retain heat inside the entire building.
It will be difficult to make an attic on your own, especially if you do not have the relevant experience, because this is a rather massive and complex structure.
The attic room can be installed under various types of roofs, but the most popular is a broken or gable design. According to the scheme of structure, they differ slightly from each other.
In order to decide which of the designs will be more suitable for your home and will be easier to install, you need to consider both options in more detail. In addition, the master who will be engaged in the construction of the mansard roof must understand which of the two types of structures of the truss system to choose.
Any roof belongs to one of the existing two types of truss systems, it is a layered and hanging structure. Each of them has a special feature, and which one to choose depends on how the load-bearing walls of the structure are located.
Hanging structure
A hanging structure is a rafter system that rests only on the extreme main walls. This happens when in the house itself, except for the outer walls, there are no capital partitions.
This design can only be used if the distance between two main walls is no more than 8 m, since this system gives a high load on the foundation. To reduce it, various elements are used in the hanging system, such as puffs and grandmas, struts and crossbars. For example, the headstock hangs the puff to the ridge connection, and the struts pull the beams to the rafter legs.
For floor beams in a hanging system, hewn logs or rather thick bars are used that are mounted on the edge. Their cross section must be at least 100x200 mm. The floor in the attic room should be as reliable as possible, and in order not to make a mistake in the parameters, it is better to entrust the calculations to a specialist.
Layered system
The layered system, unlike the hanging one, rests not only on two external load-bearing walls, but also on the main partitions installed on the foundation. Therefore, when planning the construction of an attic, it is necessary to think in advance what the design of the strip foundation will be, on which capital partitions will be installed. The layered system is perfect for an attic device, as it can withstand high loads, compared to the hanging version. It provides a good basis for floor beams and, accordingly, for the attic floor.If you make a broken version of the mansard roof, then it makes sense to use a combined roofing system, that is, the side rafters are installed according to the layered type, and the ridge rafters are installed in the form of a hanging system.
Do-it-yourself mansard roof: video, photo
When building a house from blocks or bricks with an attic, its front side is often built from the same material. This is convenient, because you do not have to calculate the parameters of these roof elements and assemble them from bars, the field of which should be raised to the wall. But it is important to understand that the walls of the building must necessarily stand on a solid foundation and have a good thickness, since such a pediment gives a significant load to the main building.
If the attic plays the role of another floor all year round, then a gable wall made of foam blocks or bricks is an excellent option for creating a living space under the roof.
In order for attic rooms with a gable roof to be spacious and have a normal height, the angle of the roof slopes should be approximately 45-50 °, depending on the width of the end part of the structure. If you take a smaller angle, the volume of the room will significantly decrease. An increase in the steepness of the slopes will make the roof unreasonably high, it will become heavier, it will have a large windage under wind load, and the cost of materials will be inappropriate.
Of course, the installation of a gable roof is easier compared to a broken structure, since even rafters are used without additional connections and any kinks. But the broken design allows you to make the room in this part more spacious, and the ceilings are correspondingly higher.
The broken system in execution, calculations, and roofing is much more complicated, but it not only creates a more spacious space under the roof, but also gives solidity to the entire structure. Its main difficulty lies in the large number of complex connecting elements. All ligaments must be carried out in accordance with the technology, otherwise the roof will turn out to be unstable.If the walls are built of brick or stone, then it is better to lay out the frontal parts in advance during the general masonry. In this case, in order to create a unique truss system, leveling at the finished gables, you can install intermediate rafters and special retaining fasteners for them.
Before you buy and prepare material for a particular system, you need to draw up a design project with the appropriate dimensions - it will become the main guide for preparing and assembling elements during installation.
Video: broken mansard roof truss system
Attic projectWhen developing a scheme for building an attic, it is better to do this in various projections in order to clearly understand how the elements of the truss system will be placed. It is important to correctly calculate what the height of the roof ridge should be, since the size of the area depends on it.
When preparing a scheme-project for the construction of a roof for an attic, it is necessary to calculate the height of the ceiling, the ridge and the total area of \u200b\u200bthe room.
The minimum height from the floor to the ridge is 2.5-2.7 m, but if this distance is smaller, then the room cannot be called an attic, the name attic is more suitable for it. This indicator is established by the norms of SNIP.
In order for all elements to be accurately drawn and have the correct location in the overall system, it is necessary to start from a figure with right angles, namely from a square or rectangle - the section of the created attic room. Based on the width and height of the future room, you will never be mistaken with the angles at which the roof slopes are located, with the location of the rafters, ridge and other retaining elements. Having found out these parameters, they must be immediately entered into the drawing.
First of all, you need to calculate the middle of the width of the front wall. Further from this point, the height of the ridge, the attic ceiling, the location of the walls (pillars) and the size of the cornice overhang are determined.
Due to the fact that each of these structures has a certain number of connecting nodes with different configurations, it would be nice to draw each of these connections separately in order to understand in detail the features of the conjugation of all elements that are connected at this point.
All truss systems include basic and additional elements that may not be found in every design. The main components of the attic roof include:
- floor beams (the basis for the remaining elements of the system). They are laid on the main walls.
- Rafter leg, consisting of two sections (in the case of a broken pattern) or straight in a gable system. The upper rafter in this case is called the ridge rafter, since it forms the highest point of the roof - the ridge, and the rafters that form the walls of the attic are called side rafters.
- Mauerlat is a powerful bar that is attached to the main side walls. Rafter legs must be installed on this element.
- A ridge board or beam is an integral element for a gable roof, but is far from always used when constructing a broken roof.
- Buildings are supporting elements that are required to strengthen a broken and gable structure. In the first case, a side and ridge rafter is attached to it, and in the latter, the stand acts as a good support for a long rafter. Moreover, the racks are a frame for sheathing and insulating the walls of the attic.
- Diagonal tie elements additionally fasten the longitudinal beams or posts and rafters, thereby making the structure even more durable.
- Interrafter runs are installed in the case of a broken roof for structural rigidity.
- Attic floor beams are used in both versions of the system - they connect the racks, and they act as a frame for the ceiling device.
In order to be sure that the project is developed without errors, it would be nice to show it to a specialist. It will determine how correctly you have chosen the parameters of the attic to the length and width of the walls of the building.
Video: mansard roof calculation using software
Parameters of materials for the construction of a mansard roof
When the graphic element is ready, then, based on the dimensions set on it, you can calculate the amount of materials that will be needed to build a mansard roof. It is necessary to choose materials according to their characteristics, which must meet the requirements of environmental and fire safety.
For wood, it is necessary to provide for treatment with an antiseptic, which will significantly reduce the combustibility of materials. For construction you will need:
- boards for rafter legs, the section of which is selected according to the results of calculations, which you will learn about a little lower.
- A beam of 150x200 or 100x150 mm - for floor beams, depending on the width between the bearing walls, the truss system, as well as for girders, valleys or diagonal legs - if, of course, they are provided for by the design.
- Beam from 100x150 or 150x150 mm, designed for laying Mauerlat.
- Usually, timber 150x150 or 100x100 mm is used for racks.
- Unedged board for the subfloor, as well as some fasteners.
- Annealed steel wire with a diameter of 3-4 mm - for fastening some parts.
- Bolts, nails, brackets of various sizes, corners of various configurations and other fasteners.
- Lumber for counter battens and battens for roofing material - depending on what type of roof will be.
- Vapor barrier and waterproofing membranes.
- Insulating materials intended for thermal insulation of the roof.
- Roofing material and special fasteners.
Rafter section
Rafters provide a roofing element that takes the main external loads, which means that special requirements are imposed on their cross section.
The size of the required lumber depends on many parameters - starting from the step between the rafter legs, the length of these legs between the support points and ending with the wind and snow load that falls on them.
The geometric parameters of the truss system are easily determined on the drawing. But to deal with other parameters, you will have to turn to reference materials and perform some calculations.
It's no secret that the snow load is different in different regions of our country. Below in the figure you will see a map on which the whole of Russia is divided into zones demonstrating the snow load.
In total, 8 zones are distinguished (the latter belongs to extreme and can not be considered for the construction of a mansard roof).
Sg - indicator in the table (carefully study the map and the table attached to it).
μ - correction factor, which depends on the steepness of the roof slope.
For example, if the angle of the roof slope is less than 25°, then - μ=1.0; if from 25 to 60°, then μ=0.7; if more than 60°, then the snow will not linger on the roof, and the snow load is not taken into account.
If the mansard roof is a broken structure, then for its various sections the load may have different values.
The angle of inclination of the roof can be determined by a simple ratio of the height and base of the triangle (usually half the width of the span) or by a protractor according to the drawing.
This indicator also largely depends on the region where the structure was built, on the height of its roof and on the characteristics of the environment.
And again, for the calculation, you will need to determine the initial data on the map and the table attached to it.
The calculation for this task will be carried out according to the following formula:
Wp = W × k × c
W - value in the table, depending on the specific region.
k - coefficient taking into account the location and height of the building (see table).
The following zones are indicated by letters in the table:
- A - open areas, forest-steppes, steppes, tundra, deserts, forest-tundra, coasts of the seas, reservoirs and large lakes.
- B - urban areas, terrain with frequent obstacles to the wind, artificial or embossed, at least 10 m high, wooded area.
- B - dense urban development, the height of buildings is from 25 m.
With- a coefficient that depends on the prevailing wind direction (wind rose of the region), as well as on the angle of the roof.
With such a coefficient, the matter is much more complicated, since the wind can have a double effect on the roofs. So, it has a tipping, direct effect on the roof slopes. However, at small angles, the aerodynamic effect of the wind is of particular importance - it raises the slope plane due to the emerging lifting forces.
As you have already noticed, on the diagrams that are attached to the tables, the sections of the roof that are subject to maximum wind loads are marked, as well as the corresponding coefficients used for the calculation.
It should be noted that at slope angles up to 30 ° (in the area of \u200b\u200bridge rafters), the coefficients are indicated both negative (pointing upwards) and with a plus sign. They somewhat dampen the wind load, and in order to reduce the effect of lifting forces, it is necessary to carefully fix the roofing material and the truss system in this area, using additional connections (for example, annealed steel wire).
As soon as the snow and wind loads are calculated, they can be summed up and, taking into account the design features of the system, the section of the boards for the rafters can be identified.Please note that these data are for the most commonly used coniferous materials (spruce, pine, larch or cedar). In the table you can see the maximum length of the rafters between the supports, the cross section of the board depending on the step between the rafters and the grade of the material.
The value of the total load is indicated in Kilopascals (kPa). It will not be difficult to carry out this value in the usual kilograms per m 2. 1 kPa ≈ 100 kg/m².
As for the value of the dimensions of the board in its cross section, it is rounded up to the standard sizes of lumber.
What tools will be needed to equip a mansard roof with your own hands?
Of course, during work you can not do without a set of tools, the list of which includes:
- screwdriver, electric drill;
- building level, tape measure, plumb line and square;
- chisel, axe, hammer, chisel;
- electric jigsaw, circular saw, hacksaw;
- carpentry knife.
If the work is carried out in the environment of competent mentors, step by step and carefully, and the tool is of high quality, the process will be much accelerated.
Do-it-yourself mansard roof: main steps + video
It is important to strictly follow the sequence of work, because only in this way the design will turn out to be strong and reliable.
- Mauerlat mount.
The installation of any truss system should begin with fixing a powerful support beam, the Mauerlat, at the end of the side walls of the buildings. It is convenient to install rafter legs on it. It is made of high-quality bar 100x150 mm. Mauerlat is laid on roofing material waterproofing, laid along the upper end of the wall (regardless of the material).
Thanks to the mauerlat, the load is evenly distributed over the walls and transferred to the foundation. It is fixed to the wall by means of metal studs, which are previously embedded in a crown or concrete belt running along the upper edge of the building wall or with 12 mm anchor bolts. They should go deep into the wall by at least 150-170 mm. In the event that the Mauerlat is installed on a wooden wall, then the bars are attached to it using wooden dowels.- Installation of the truss system.
The installation of the roof structure begins with the installation of floor beams, which can be mounted on top of the Mauerlat (if you plan to take the beams outside the room, increasing its area). In this design, the rafter legs are fixed directly to the floor beams.
Otherwise, they can be laid on waterproofed walls and fixed with brackets or corners to the inner edge of the Mauerlat. This option is used if the rafter legs need to be fixed directly to the Mauerlat.
Racks should be at the same distance from the middle of the floor beam. In the future, they will determine the location of the walls of the room, namely its width.
Bars for racks must have a section corresponding to the size of the floor beams. Racks are attached to the beams with wooden plates and special corners. But for starters, they are baited with nails, after which they are leveled with the help of a plumb line and a building level, and only then they are thoroughly fixed with the expectation of upcoming loads.
As soon as the first pair of racks is installed, they are fastened on top with a bar (tightening). It, in turn, is connected using metal corners with racks.
When the puff is fixed, you will get a U-shaped design. On the sides, layered rafters are installed on it, which are laid on the Mauerlat or attached to the floor beam with the second end.
A groove (special notch) is cut out on the installed supports for the beam or in the rafter. With its use, the rafters are installed on the Mauerlat beam and fastened with metal brackets.
To ensure structural rigidity, struts can be installed from the base of the rack to the middle of the side rafter. If this is not enough, and you do not feel sorry for the material, then it would be nice to strengthen the overall design with contractions and additional racks.
Then the middle is calculated on the puff. A beam will be attached to this place, which supports the ridge connection of the upper hanging subsystem of the rafters.
The next step is the installation of ridge rafters. They can be fastened with various connections - these can be powerful bolts with metal washers or plates or a metal lining.
After their installation, a headstock is attached to the middle of the puff and the ridge.
Upon completion of work on one part of the truss structure, it is necessary to make the rest according to the same principle. The distance between adjacent rafters in such a system should be no more than 900-950 mm, but the best option would be an interval of 600 mm, which will give the structure the necessary stability and rigidity and will be convenient for insulation with standard mineral wool mats. But this significantly complicates the structure and increases the cost of materials.
First, the side parts of the assembled system are installed, after which the intermediate ones. They are interconnected by runs that are installed between the upper ends of the racks and work like spacers. So, it turns out a rigid structure of the attic rafters, where there will already be a ready-made frame for wall decoration.
Mansard roof waterproofing
As soon as you build the truss system, you can start finishing it with insulation and other related materials.
It is worth noting that the first coating over the rafters should be a waterproofing and windproof film. It is attached to the rafters with a stapler and staples, starting from the eaves. The canvases are overlapped (200 mm), and then the joints are glued with waterproof tape.
A counter-lattice is stuffed on top of the waterproofing, which will better fix the film on the surface and create a ventilation distance between the roofing and windproof material. Usually the counter-lattice is made of boards with a thickness of 50-70 mm and a width of 100-150 mm.
A crate is fixed perpendicular to it, on which the roofing material is laid. As for the step between the slats, it is calculated depending on the size and type of sheet roofing material, taking into account the overlap required for it.
If you use a soft roof, then plywood sheets are usually fixed to the counter-lattice.
How is roofing installed?
Roofing material is fixed on the prepared plywood or crate. Usually, its installation starts from the roof eaves and then alternately, from one of the edges - depending on the type of roof. The roofing sheets themselves are overlapped. If a metal tile or a metal profile is used for coating, then this material is fixed with the help of special self-tapping screws with elastic gaskets. Usually fasteners are matched by color to the material.
The most difficult stage in covering a sloping roof is the transition from layered side rafters to ridge rafters. Some difficulties may also arise if there are ledges on the roof for arranging the roof over windows or balconies.Moreover, if a chimney pipe goes to the roof, it needs a separate opening in the insulation layer and the truss system, and on the roof - a device around reliable waterproofing. It is worth noting that the construction of any roof, including such a complex one as an attic, is very responsible and dangerous, and therefore requires increased security measures. If you do not have experience in such construction processes, then it is better to entrust their implementation to specialists or invite an experienced craftsman, under whose control to perform all actions, carefully and carefully.
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