During the construction of a new house, the question often arises about the amount of lumber for the roof. And this question is really important. After all, various materials for the roof are not at all cheap, and if you buy too much, then the money will simply fly out of the pipe. At the same time, if there is not enough material, this will cause construction downtime and, possibly, additional costs for the delivery of a new batch. That is why the calculation of materials for the roof is a burning issue on which the final stage of building a house depends.
As you know, when designing a house, a preliminary calculation of the forest on the roof is made. At this stage of work, the strength of the structure and its resistance to climatic conditions are determined. If structural strength calculations have not been carried out, then the roof may eventually turn out to be unstable to the action of wind and snow, which can lead to inevitable consequences.
Well, let's take a closer look at the calculation of the material on the roof of the house. In preliminary calculations, the thickness and type of insulation, the material for creating the crate, must be taken into account.
Types of roofs, materials
Roofs can be made both in a classic form and in a completely fantastic one, but basically it is:
- classic single or multi-slope;
- broken line;
- hip, semi-hip, tent;
- oblique;
- domed;
- folded;
- cruciform;
- flat;
- spherical;
- spire-shaped.
Various loads affect the rafters - their own weight and the weight of the roofing material, wind loads and the effects of precipitation. For the arrangement of rafters, battens and Mauerlat, high-quality and well-dried lumber from coniferous wood is used. It is this wood that is most resistant to moisture and decay.
A roof is laid on the rafters, the calculation of materials and the method of fastening of which depends on the type chosen. It can be nails, dowels or special glue. As a roof, you can use different materials - aluminum, copper, ondulin, ceramic or metal tiles, bitumen, polymers, etc. Styrofoam and glass wool are most often used as insulation.
How to calculate the materials for the roof
After the rafters are installed on the waterproofing, you can start laying the counter-lattice. It is designed to drain condensate and circulate air. can be either continuous or with a certain step. It all depends on the chosen material of the roof and the angle of its inclination. The step should be considered carefully so as to avoid deformation or collapse of the roof.
Calculation of lumber on the roof
The calculation of the material for the roof of the house is affected by the step or distance between the bars. In order to determine it, you must first (primary and secondary). In this case, the main point is to provide some margin of safety to maintain the integrity of the roof in extreme conditions (heavy snowfall, hurricane).
The main load is the weight of the roof elements and the weight of the roofing cake. The secondary load is the force of the wind, rain, snow, etc.
The calculation of the roof is carried out according to the following scheme:
The calculation of the roofing material for the roof and the main loads is best done using a calculator or an Excel program. This will help avoid mistakes. Also on the Internet you can find various calculator programs that help calculate the various characteristics of the roof.
Below we give some examples of calculations of various roof parameters for several types of materials. Suppose that we have already calculated the Mauerlat parameters, also we, the slope and height of the roof. Using the normative table, it can be determined that the total load on the roof structure will be 2400 kg / m, while the permissible load per 1 linear meter of wood is 100 kg. Thus, it can be done by calculating the required footage of the rafters. To do this, simply divide the first indicator by the second: 2400/100 = 24 m.
If the length of one rafter is 3 meters, then their total number will be: 24/3 = 8 pcs. Naturally, the number of pairs will then be 8/2 = 4. The maximum step is calculated based on the length of the roof (in our case, it is 4.5 m) and the number of pairs: 4.5 / (4-1) = 1.5 m. In this formula we subtracted the very first from the number of pairs, that is, in total there are three gaps between the rafters.
In order to provide the roof with greater stability and strength, the rafters are installed at a smaller pitch. To do this, you can add a few more pairs to the estimated number of rafters so that the distance between them does not exceed 100 cm.
Calculation of materials for construction, detailed video:
Based on this, to fill one row, it is necessary to use 6 sheets of metal tiles. Next, the number of rows of material from the ridge to the cornice is calculated.
- the distance from the eaves to the ridge is measured;
- the overhangs of the eaves are calculated;
- the value of the vertical overlap is determined (no more than 15 cm).
For example, the width of the slope is 4 m, and the overhangs are 30 cm. Thus, the total distance from the lower edge of the roof to the upper one is 4.3 m. The standard length of the metal tile sheet is 1 m. This means that the effective indicator of this parameter will be 85 cm ( subtract the amount of overlap). We divide the indicator of the total length of the roof by the effective length of one sheet and we get that 4.3 / 0.85 = 5.05 sheets must be used for laying. Since rounding down we will have a shortage of material, in reality we will have to use 6 rows.
We multiply the indicator of the number of sheets vertically and horizontally and get the total amount of material per slope: 6 * 6 \u003d 36 sheets.
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