Foundation depth: we calculate how deep the foundation should be up to a centimeter
At the stage of designing a foundation for a steam room, the most difficult moment is the correct calculation and laying of the foundation. But, if you can somehow figure out its type and design on your own, based on the possibilities of the budget and the popularity of a particular type in a certain area, then what is the correct depth of the foundation is another question.
Why are foundations buried in the ground at all? Yes, because several forces always act on the foundation of any house at once: the gravity of the structure itself, the movement of soils invisible to the eye, landslides and precipitation. That is why it is so important to put the bath on a really solid and solid foundation, thus transferring to it all the calculated loads. And how to correctly calculate this depth, the article will tell.
Foundation depth: dispelling myths
Yes, it seems that the simplest solution is to bury the same bath deeper, and it will last a hundred years. In fact, this is not so, and today there are a lot of myths among builders about how deep the foundation should be.
The deeper the better?
Even among fairly experienced architects, there is a myth that the deeper the foundation, the stronger it is. Of course, you can understand the desire of the customer to save money, as well as the foreman, who is trying to convey to the fact that with a foundation “at random” it will not work. But digging deeper does not mean that it will turn out stronger.
So, the depth of the zero level is determined by many parameters - and it is better to entrust this issue to specialists. Engineering and geological surveys are being carried out, the type of soil is being investigated, the level of groundwater and its freezing are being measured. The design feature of the building also decides a lot: the number of floors, superstructures, wall material - and the bath in this parameter is just less demanding on the power of the base than a residential building. You can read more about determining the depth of the foundation in a small interesting book by V.S. Sazhin “Do not dig foundations deep”.
Does depth really always “save”?
But it is far from always necessary to strive to make the foundation deeper if the soil is restless - in fact, there are methods on how to compact and harden any soil. And therefore, if the bathhouse will not be built at all massive, there is no point, as builders like to say, "to bury money in the ground."
So, the first thing to do is to study the problem well. For example, if water is often visible at or close to the surface, proper drainage around the foundation will save. After all, it is pointless to strengthen the foundation in this case by increasing the support - the zero level will continue to “walk”, and it will take a lot of money for such a method. There really is no lack of depth here.
But if landslides are observed along the perimeter, the foundation is washed away and even starts to sag somewhere - it is not necessary to strengthen it, but the soil. So, silicification is good for sandy soil - the soil around the foundation is poured with a mixture of liquid glass with water, one to one, and the resulting wet sand is well tamped. Or chemical reagents are used: wells of small diameter are drilled, and special resin compounds are pumped into them. Durable and inexpensive, and for weak soils - what you need.
We determine the depth by the formula
Here is a standard formula by which you can calculate the depth of the foundation:
Hp = mtmHн, where:
- Hn - depth of soil freezing,
- mt - 0.7-1, the coefficient of influence of the heat of the building on the freezing of the soil near the outer walls,
- m - 1.1, coefficient of working conditions.
Soil type, temperature and other parameters
So, how to correctly calculate the depth to which the bath should be laid?
Average temperature of the region
Many today, of course, rely on average calculations and pour foundations 90 cm deep, but experienced builders always make sure in case of a cold winter and reach 1.10 m and no less! Moreover, frosts in Russia are certainly not uncommon. Why, and since Soviet times, the foundation has been laid to a depth of 110 cm - so even in frosty winters, heaving of the soil cannot disturb anything.
Do we heat the basement?
Unheated structures are laid 10% deeper than the level of soil freezing depth, and heated structures - 20-30% higher. Another point: under the inner walls of the bath, the foundation can be deepened less - allowed by building codes. But not less than 40 cm is important!
Soil freezing depth
So, in all areas - their own characteristics of the soil, its density and water saturation. Take an interest in such characteristics from the owners of neighboring buildings. But pay attention: if there is a reservoir nearby, then the winter swelling of the soil may be much larger than expected. How to find out the normative depth of soil freezing in your area? Use this map here:
soil properties
What is seasonal soil heaving? This is underground water, which freezes in winter, increases in volume (remember school physics) and pushes out what is in this soil. In the spring, it melts and lowers the ground again.
For example, according to official information, 80% of soils in the Moscow region are heaving. These are clays, loams and sandy loams, and all this swells a lot in seasons. On peat soil, there is no need to talk about depth at all: the only possible foundation here is a floating slab.
No less important for determining the required depth of laying the tape and any other foundation is water saturation: if it is clay and it is heaving, then the foundation will have to be deepened significantly. In extreme cases, it is better then to use a stove - for a small bathhouse, that's what you need.
In general, the ideal condition for any foundation is when groundwater is above the freezing depth of the soil. After all, when they cross, groundwater freezes and “swells” the soil, and unevenly, which leads to a warp of the foundation. And these are cracks and even worse. Because the force of seasonal swelling of the soil is 10-15 t / m2, not bad, right?
Shallow foundations - benefit or competent calculation?
And, finally, when determining the depth of the foundation, you need to pay attention not so much to the type of soil, but to the array of walls and their material. So, profiled timber and logs, from which the Russian bath is built most often, is a flexible and elastic material. After all, a tree is a fibrous structure, and then it works great for deformation, and quite easily survives any movements of the foundation. That is why it is recommended to build a steam room from a log house on a strip shallow foundation with a depth of only 50 cm - this is enough. A frame bath can also have the same basis - after all, all its elements are connected by corners, and therefore you also don’t have to worry about cracks and deformations.
Of course, shallow foundations are most often erected in order to save money on the construction of a bath: there is little earthwork, and the coarse sand used replaces the soil and helps to reduce the degree of deformation. Such foundations can move imperceptibly to the eye, but massive buildings from this can completely collapse. After all, such wall material as brick and stone will not tolerate vibrations and stretching. Both stone and brick are fragile, and therefore, regardless of the weight of such a bath, the foundation for it is necessary, as they say, unshakable - such that it does not tilt even a millimeter. Otherwise, the walls in the first year will “please” by no means small, rapidly growing cracks.
And even after such information, you find it difficult to correctly calculate how deep you need to dig the foundation for your bath? Welcome to the "" section!
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