Strengthening and strengthening the foundation of the house is necessary when cracks appear in the walls or base, and also if an increase in load is planned: an attic will be erected or a screed will be poured instead of wooden floors.
There are many amplification methods, but not all of them can be implemented by hand. There are some situations in which you simply cannot do without professionals. Sometimes the destruction is so great that building a new house is cheaper than repairing the foundation. So both the method and the mode of action depend on the degree of destruction and the reasons that caused it.
Most often, problems arise with strip foundations of shallow occurrence (this is if the base ends above the depth of soil freezing). They do not always create problems, but when conditions change (changes in the level of groundwater, ground shifts, etc.), they can be squeezed out by heaving or eroded.
The least problems happen with the slab foundation. Its amplification is a rare problem. If any measures are required, then usually it is the drainage of water or, in extreme cases, the cementation of the underlying loose soils.
The easiest way to repair the foundation of a wooden house. Due to its fibrous structure, wood (a log or a bar, anyway) normally tolerates all work, and compensates for distortions due to flexibility. With brick, concrete, block houses, the situation is different - here the slightest mistake can lead to the destruction of the wall. Therefore, it is necessary to make the intervention zones (strengthening works) very small - so there is less chance of causing serious harm.
The choice of foundation reinforcement method depends on the cause that led to the appearance of cracks. Therefore, the first step is to diagnose. To do this, we perform two activities:
- install beacons on cracks on the walls;
- we examine the foundation in places of destruction.
The activities are not very complex, but from them you can learn quite a lot of information that will help in choosing a course of action.
Installing beacons
We need to know the following things:
- whether the process of destruction continues or has already stopped,
- if it continues, then in which direction does the shrinkage occur, and at what speed;
- which caused cracks.
To do this, markers are placed on the cracks at the top and bottom closer to the edges - these are small patches made of gypsum, a mixture of cement and gypsum, plaster, etc. The main condition when choosing a composition is the fragility of the material, so that in case of movement it bursts.
Make lighthouses across the crack. The depth and width of the patch is 3-5 cm, the length is 10-12 cm. First, they clean the place where the markers will be installed (for better adhesion), then the finished solution is applied with a spatula. After that, a long narrow horizontal line is left on the front surface: a ruler or trowel is pressed in about 3-4 mm with an edge. The beacon is ready. They need to be made at least two pieces on each crack.
Then the condition of the markers is periodically checked. In industrial conditions, they keep a journal. For a private trader, it also does not hurt to make notes - then it will be possible to determine what caused the activation or vice versa, stopped the expansion of the crack.
If for several weeks no changes have occurred with the beacons, then the shrinkage of the building is completed. In principle, you can simply close up the cracks and do nothing else: the wrong method can aggravate the situation, not improve it.
If the cracks continue to expand, it is necessary to determine which part of the building "sits down". It is from this side that it is necessary to carry out work.
That's all the information this measure can give. Now we will determine what led to the destruction.
Roem pits
If there is water at the bottom of the pit, it is necessary to carry out work on drainage - to create a drainage system
In those places where the process of crack expansion is taking place, we tear off the foundation, but only to the depth of its occurrence, not lower. Moreover, the length of the pit should be small, and the width - so that it can be used with a shovel. It can then be expanded if necessary.
Since repair and restoration work is a risky business, it will not be superfluous to take precautions - install props that will support the hay at the excavation site. Act carefully.
We determine the causes and methods of strengthening
Using the data obtained from monitoring beacons and digging a hole, we find the reasons that led to the appearance of cracks in the foundation and walls. Depending on the reasons, the method of eliminating cracks is selected.
Spillage of cement
As the foundation is excavated, you can evaluate its condition. Often, unfortunately, the cause of cracks is a violation of technology and the use of improperly composed concrete. The concrete may crumble due to the fact that the water has changed its acidity, has become more alkaline or acidic, and corroded the material. In this case, it is necessary to divert water, remove all crumbling parts in a small area. Next, you need to strengthen the crumbling solution.
This is done using a special apparatus that delivers binders or cement mortar deep into the foundation. This method is called cementation.
First you need to make holes in the foundation. They are made at an angle, at 0.4-0.6 of the depth of the base. In order not to cause harm, they are placed in a checkerboard pattern, at a distance of at least 1 m from each other. The prepared holes are first cleaned of debris (blown under pressure), then a deep penetration primer is poured, which will bind the crumbling particles. After that, a reinforcing composition is introduced into the holes. After hardening of the impregnation, the condition of the foundation improves.
Soil washout
If voids were found when digging a pit, this means that the soil was washed out from under your building. In this case, water will appear at the bottom of the ditch after a while. If this is the case, you need to carry out drainage work to divert water from the foundation or arrange a drainage system. The choice of a set of measures depends on the type of soil and the amount of water.
After drainage, you need to make waterproofing, or (better) insulation of the foundation and basement. Carefully cover the voids with soil and tamp. A necessary measure upon completion of these works is a blind area. And, again, better insulated.
This complex - drainage, waterproofing and blind area - is necessary even if the water just appeared in the pit. This level of subsoil waters is too high - you dug a pit to the depth of the foundation. And if water appeared in it, it means that it has its negative impact on your home. Even if it does not wash out the soil, it is better to take it away. And it is better to do this with the help of a drainage system and a blind area.
Subsidence of unreliable soils
If the subsidence is significant, the soils are sandy or sandy, it is necessary to strengthen the soils themselves. In this case, wells are drilled that end under the base - its sole. Strengthening compounds or cement mortar are then pumped into them.
If there are obvious faults and shifts on the foundation, topping up the foundation or strengthening it with piles is required. Such damage occurs either due to ground movements, or due to a change in the load on the house: when pouring a bulk cement screed, building an attic, etc.
First, we determine which of the parts sags. How? By beacons. We put a risk on the markers. When the right side of the house sags, the risk moves down on the right, when the left side sags, the left one floats down. If different risks go down in different parts of the building, then the middle of the building is sinking.
Determine which part of the building shrinks
Having decided which part is settling, we know the scope of work: on the right or on the left - when one of the parts subsides, and around the entire building, when the middle subsides. The next step is to decide on the method. There are two of them in this case: strengthening the foundation with piles and a cement jacket.
The pile method involves deep drilling and the installation of bored, bored or bored piles. They connect to the existing foundation. Due to deep penetration, they can help with a large thickness of unreliable loose soils, when injections will not achieve anything. Can be installed on one side or around the perimeter.
Creating a cement jacket
This is one of the few methods of strengthening foundations that you can implement yourself. But you need to act carefully and not violate the technology.
The idea is to expand the base of the sagging, more loaded part, thereby stopping it. This method is used for shallow strip foundations (above the level of soil freezing).
Creating a cement jacket (clip) is an effective, but difficult method for strengthening an old foundation
For this, the part of the foundation on which the work will be carried out is divided into three parts. But the length of one part is no more than 2 m. If it turns out more, make more fragments. Work begins with located in the middle. This section of the foundation is opened to the depth of the foundation.
The method consists in the fact that holes are drilled in the foundation, reinforcement is inserted into them, which will be several tens of centimeters longer. Reinforcement diameter 14-16 mm. It clogs tightly: it is on it that most of the load will fall. Put the pins in increments of 50 cm.
The installed pins are tied with transverse reinforcement bars using a knitting wire. Then the formwork is installed, the solution is poured into it. After it sets (at least two weeks), they move on to the next section. So, alternately, bypass all the necessary plots.
Strengthening the foundation with bulls
This method is similar in methodology to the previous one, only the order of work is changed. It is more acceptable if the corners “sag”. In some cases, it is used when the load increases (floor superstructure or pouring a large area screed).
Reinforcement is done in the corners. Pins are also driven in, tied up, formwork is installed, into which the concrete mixture is poured. With a large length or a significant increase in load, they also make intermediate poles-bulls. After setting, they are tied with a tape buried at the same distance as the base made earlier.
Strengthening the rubble foundation
Repair and reconstruction of the rubble foundation has some features. Most often, problems arise with the foundations of the old masonry. In them, backing behind the front row is not always done carefully, there are voids.
Previously, stones of different strengths were often used in masonry, and some of them crumbled over time, insufficiently strong mortars crumbled, washed out or spilled out. All these shortcomings get worse over time. Problems manifest themselves when construction is activated in the district or when the level of groundwater changes (caused, often, by the same construction).
The method of strengthening the rubble foundation depends on what problem caused the destruction. If it is groundwater, carry out drainage work, divert water from the foundation. Then you make a blind area around the house.
If the voids have sunk, the mortar has crumbled, cementation of the tub is necessary. To do this, they dig out the foundation (plots, if the house is brick or block small - no more than 2 m). The entire surface is cleared of the earth. This should be done “dry”, I do not use water - the wet masonry quickly collapses. After that, the area is dried - left open for a while. If voids are found during the work, tubes are inserted into them through which cement mortar is injected.
Strengthening one of the sides can be done using the cement jacket described above. Only the pins are hammered into the seams, it is not necessary to drill stones. If there are crumbled stones, they are removed, the voids are filled with mortar, inserting pieces of reinforcement into it. For better adhesion to the old foundation, the old mortar is removed from the seams in some places to a certain depth. It will be replaced with a new one when filling. That's all the features.
Strengthening the rubble foundation with a cement jacket
When soil is eroded, the solution is similar to the above - diverting water, and then cementing the voids through pipes driven into the soil.
Results
Repairing and restoring a foundation is no easy task. Often only professionals can handle it. But it often happens that the cost of restoration is very high. Then you can strengthen the foundation with your own hands.
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