The basis for the construction of any building is a very important object, on which the durability of the future construction depends. A pillow under the foundation provides the strength and stability of the site performing the support function, and it is thanks to it that the probability of upset is significantly minimized. This material will help to find out whether such a design is needed, and how to perform such an important process with your own hands.
Why do I need a substrate under the base?
It's no secret that a poorly laid foundation will make life in the house impossible. In case of incorrect installation of the base, the walls of the building will crack, the door and window openings will skew, and drafts will settle for ever inside the house. That is why the foundation device should be carried out in compliance with the technology, an obligatory item of which is a pillow for a strip foundation. This load-bearing element will correctly distribute the load from the walls of the house to the ground and exclude its subsidence. Also, with its help, it is possible to raise the lower part of the support above the groundwater level.
DIY pillow
In practice, several types of base are used as a basis:
- from sand;
- from gravel;
- from sand and gravel (combined);
- from concrete.
To level the bottom of the trench or pit at the site of the future foundation, it is necessary to fill up a ten-centimeter layer of sand or gravel. Concreting is applied where the base wall should be expanded or there is a need for reinforcing the belt under the FSB blocks. It is not difficult to make a filling from rubble with your own hands, you just need to remember that the embankment should be lower than the base itself, and its width will be twice as much as the similar foundation parameter. Crushed stone bedding is usually about 30 cm, one third of which is sand, and two thirds is gravel.
After leveling the bottom of the pit, a pillow is built under the foundation. The process starts with laying a layer of sand, which is spilled with water and rammed. In a similar way gravel is laid. To create a concrete support, it is necessary to fill up a layer of crushed stone of 5-10 cm on a flat area with the condition of compulsory compaction. Now we proceed to the installation of the formwork according to the dimensions of the fill, which must be reinforced along the length. At the end of the process, pour concrete mortar, which can be equipped with vertical reinforcement bars. This will make it possible to connect the monolithic support with the foundation.
The pillow from crushed stone is correctly made so that the finished base in accordance with the level corresponds to the mark in the design documentation. The most reliable support under the foundation slab is a concrete pillow. You can also build it yourself, although it will take a lot of time, and its cost will be higher due to an increase in the number of consumables. The thickness of this supporting platform should exceed the foundation by 30 cm, the same applies to the width (15 cm on each side).
Sand backfill
A sand cushion under the foundation is the easiest and cheapest type of bedding, so those who want to save money, speed up the construction process and do it yourself do it. Although such a platform does not seem very reliable, it copes with the mission assigned to it. Sand cushion under the strip foundation saves the base from undermining, and also provides an allowable load on its lower part.
To make a good bedding, choose coarse sand and cover it with a layer of at least 20-25 cm.
The loose mass must be properly leveled and tamped with a vibrating plate. During tamping, be sure to spill the pad with water for greater compaction.
As you already understood, the pillow for the foundation is made exclusively of coarse sand. On weakly bearing soils, sand alone is not enough, so the area is additionally reinforced with gravel. Such preparation for the foundation practically does not shrink after the construction of a massive house with any area, and that is why it is very important to properly tamper, especially if you do all the work yourself.
Gravel filling
This base has a clear advantage over the previous one - it is stronger and more durable, since gravel acts here as the main component.
Before making crushed stone underneath the foundation slab, you need to line the soil with river sand of a large fraction (layer 15 cm), which is evenly leveled and compacted. Then a layer of crushed stone is poured (20-25 cm) and also attached to the tamping machine.
Carefully make sure that the pebbles are snug against each other and fill all the voids. To perform such a process, a vibrating plate is needed, otherwise it will not be possible to achieve the necessary density. Since the foundation device will begin with the crushed stone layer, the pillow should be at zero. This type of substrate is suitable for the further construction of any type of structures made of various materials.
Concrete cushion for monolithic slab
Finally, we will consider how to make the installation of a concrete site with your own hands. This design has only one drawback - its high cost, but the rest of this project consists of solid advantages.
First of all, I would like to note the endurance of the pillow, provided that the installation work was carried out correctly, but they look like this:
- The plot is cleaned of plants and debris.
- The soil is carefully leveled.
- Crushed stone is laid with a layer up to 10 cm thick.
- Crushed stone is rammed.
- Mounted wooden formwork around the entire perimeter of the pillow.
- The foundation site is being reinforced.
- Concrete is poured. Its brand depends on the weight of the future building.
- The solution is rammed with a deep vibrator.
- The design is left to dry completely (1 month).
Such a foundation is ideal for future home construction, although it is the most difficult to make with your own hands..
Following the recommendations of the article, as well as having weighed all the pros and cons, there is every reason to argue that a pillow under the strip foundation is definitely needed, and it is strongly not recommended to save on it.