Slab foundation. Do-it-yourself step-by-step instructions
The slab foundation is the most durable and reliable foundation of all known types, but it is also the most expensive. The high price of such a foundation is due to the large amount of costs for concrete and insulating materials, because the size of such a foundation is equal to the dimensions of the base of the house.
Foundation slab. Pros and cons of a slab foundation at home
Advantages in construction
- The indisputable advantage of the slab foundation is that it makes it possible to build, in general, any building (heavy house, bathhouse, etc.) even on wetlands or peat bogs.
- The design of such a foundation, which is a monolithic reinforced slab, allows it to “float” on the soil surface, moving along with the migrating upper layer of wet soils. For this feature, the slab foundation was called floating.
- The difficulties of erecting a slab foundation are usually associated with the moment of calculating the necessary materials.
- This kind of foundation-monolithic slab will become the floor for the basement of the house, which is quite convenient and practically profitable.
Cons of a monolithic slab in the foundation
- Of course it is expensive, not everyone can afford it. And although the slab foundation is the most expensive of all, it is not worth saving on its construction, because the stability and durability of the entire building depends on its strength.
- If you suddenly want to move a frame house, you should say goodbye to the foundation, unlike those that can be unscrewed and used again.
Building a foundation. Installation steps
1. The slab foundation is a shallow type of foundation. After the main markup, a foundation pit is dug on the building site. The slab foundation is arranged in such a way that it does not protrude much on the surface of the soil. The depth of the pit is calculated based on the following dimensions: the height of the foundation itself (20-40 cm) + the height of the sand cushion (at least 10 cm) + the thermal insulation layer (up to 10 cm).
We fall asleep sand. Leveling the base
2. A sandy layer is poured onto the bottom of the pit, which must be carefully compacted. Some builders fill in a layer of rubble, but this is not necessary, it will still grind into sand. The foam complex is also not required, but firms do it with it in order to earn more. Then a layer is laid, which can be used as roofing material, overlapped and soldered with a gas burner. Depending on the climate, a heat-insulating material (foam or polystyrene) is laid on the waterproofing layer. You should be aware that this foundation requires insulation not only at the base of the slab, but also from the sides of the structure.
3. The next stage is the erection of formwork around the entire perimeter of the future monolithic foundation slab. 
Formwork boards are also covered with waterproofing.
4. Further, over the entire surface of the foundation in the form of a lattice, a reinforcing cage of rods with a diameter of at least 12 mm is laid. The rods are fixed to each other with wire, the size of the windows obtained after the bundle can be 20 by 20 cm or 30 by 30 cm.
Preparing the frame before pouring concrete
5. When the reinforcing cage is installed, pour the concrete mixture. For a monolithic slab foundation, a sufficiently large amount of concrete mixture will be required.
If it was not possible to pour the slab in one step, it is possible to postpone the pouring of the second layer for a period of no more than 12 hours, otherwise the foundation may not turn out to be as strong as we would like.
We fill the slab foundation with our own hands
There is another option for erecting a slab foundation, when ready-made reinforced concrete slabs are placed throughout the formwork example, which are poured with a concrete screed. However, this version of the foundation will be inferior to the monolithic one in strength. In addition, for laying heavy concrete slabs, special equipment will be required, which is unlikely to be more cost-effective than the installation of a slab foundation of a monolithic structure.
As soon as the concrete hardens and gains strength, the foundation for your future home is ready.