Slab polyurethane foam insulation – simplicity and efficiency

Slab polyurethane foam insulation
Popular slab insulation materials, like mineral wool, cellulose fibres or styrofoam, may be not enough for a longer period due to their properties. In that case the best solution is the sprayed polyurethane foam.

When and how to insulate the slab?

Slab is very important for the house. It closes one storey on one side with a ceiling, and gives floor for the storey above.

Have you thought of when the slab over the last storey should be insulated, so that the cold loft is not the weakest link for the thermal insulation of the entire building? The answer is: if you attic is not used, because it is used as a storage for things you don't need. There are attics of low and rather flat roofs marked as unoccupied during the design phase.

Popular mineral wool tend to absorb moisture, so if laid on a fresh slab it will absorb water remains from the concrete slab and will as a result reduce it thermal insulation properties. An additional disadvantage of wool as well as styrofoam is that they are difficult to adjust to the shapes of the insulated surface.

The polyurethane foam is the right solution which is perfect for slab insulation. What's important: unlike wool, the foam preserves its thermal and waterproofing properties for years. Foam is applied evenly forming a uniform layer retaining heat in the building.

Slab polyurethane foam insulation – economic benefits

Slab foam insulation Slab insulation saves money – the lack of insulation causes significant heat loss and enormous heating bills. If you live in an old building, you should check if your slab is insulated enough. If you are not sure about it, you should carry out a thermos visual test that will give you detailed data.

For newly built houses, valid construction law regulation requirements should be met. Note that since 2017 the insulation of the slab under an non-insulated attic is legally required. As a result, the heat transfer coefficient will be max. 0.18 W/(m²K).

Do you know slabs over the basement have a significant influence on the energy efficiency of your building? Like the attics, if the basement upper slab is not properly insulated, the heat losses can be high.

Foam insulation seems a very good solution in all cases. The foam provides not only thermal comfort, but also an acoustic barrier for each storey. Moreover, it eliminates thermal bridges, perfectly covers the insulated wall and it doesn't absorb moisture. It is not attractive for animals, so you can rest assured no uninvited guest will live in your house. And what is the most important for your family – the foam creates friendly environment without allergens, dusts and any types of mould and fungus.

Despite the higher price of PUR foam insulation, the benefits surpass the costs. The long-term and reliable insulating performance of this material will pay back in a few years as energy savings. Remember – insulation is not changed every year!

The slab foam insulation is different, depending on its type, structure and material of the slab. The type of insulation is chosen only after those criteria are considered. So how is a concrete and a frame slab spray foam insulated?

Slab insulation with polyurethane foam – concrete

Slab insulation with polyurethane foam For concrete slabs, closed-cell polyurethane foams of different densities are often used, depending on the insulation hardness requirements (i.e. mechanical resistance).


If the concrete slab is to be insulated from the top, harder foams are used. This is because they are loaded by a layer of floor concrete, building equipment and everyday use.

You can also apply foam to a concrete ceiling, e.g. in basement, and insulate the living area on the side of non-insulated rooms. In this case closed-cell foams are also used, usually of lower thickness, as ceiling insulation is not loaded.