A simple way to save money: building a strip foundation without wooden formwork boards

Everyone who is faced with construction this season knows that lumber has risen in value for a strong one. Grew up a lot - that's putting it mildly. The price for six months has increased at least 2 times! Each piece of wood has become, as they say, worth its weight in gold.

And for the construction of any foundation, formwork is required. As a rule, a board of 150x50 mm is used. And it is needed on a strip foundation with a height of 0.5 m and a house size of 10x10 m, more than 3 m3. In our region with delivery - this is now the amount of 70 thousand. rub.

You can calculate the volume of the board here: https://calcstroy.ru/fundament/lentochnyj-fundament

This formwork can be covered with polyethylene (inside and outside), try not to stain it with concrete and then use it for roofing or floors. And if it is still far from the roof, is it possible to somehow do without formwork from a board, to reduce costs?

You can remember the old way of saving - pouring a strip foundation into a trench.

Polyethylene is laid in the dug trench of a shallow strip foundation (so that the concrete milk does not go into the ground) and is reinforced.

And what next after pouring concrete? Will the walls start at ground level? And if there is a small drop, then in one part of the walls will be below ground level. A height of at least 0.5 m of earth must be waterproofed, insulated and isolated with materials, emphasizing the foundation (artificial or natural stone, basement siding, plaster with imitation, etc.)

If you use a brick of low strength and frost resistance, do not immediately waterproof, then this can happen:

The brick becomes waterlogged and collapses in 1-2 winters. There is an option to use high-grade solid brick, for example, M200. In our region, this has a cost of 33 rubles / piece. This is more than 17 thousand / m3. An ordinary building brick costs from 10 rubles / piece. This is slightly more than 5000 rubles / m3 and is comparable to high-quality concrete of the M350 brand.

But I would choose a different method when pouring the foundation. Do the formwork, but immediately insulated and support it not with an edged board, but with sawing waste, a croaker. According to this principle:

We make shields from slabs, which many sawmills give away for free. We saw it there and bring it in our trailer. Or we bring it like firewood in a truck.

Shields can even be with slots (if the foundation is low). EPPS (Penoplex) carefully pierce with plastic dowels, which fix the insulation to the walls. When the concrete sets, the insulation will be securely fixed. You will get a strip foundation insulated on both sides. The foundation still needs to be insulated, but later.

After the slab shields are disassembled and sawn for firewood. This is exactly what I did when I was building the foundation slab: I supported the concrete slabs of the permanent formwork with a slab.