Lost formwork is a type of concrete form which, once the concrete has set, remains permanently in the structure and performs additional functions - usually insulation or construction. In the case of an insulated foundation slab, these are panels of thermal insulation material (usually EPS or XPS boards). They form the form for the concrete pour and at the same time provide thermal insulation for the foundation.
In such a solution, the foundation slab is:
- monolithic - the entire load-bearing structure is a uniform, reinforced concrete slab,
- heat - lost formwork acts as thermal insulation layer both underneath and on the sides,
- ready for further construction stages - once the concrete has set, there is no need to dismantle the formwork, which speeds up the work and reduces construction waste.
This solution is particularly popular in energy-efficient construction and prefabricated, where accuracy, speed of execution and minimisation of thermal bridges are important.
