Floor insulation: that's how it's done

Without floor insulation, a lot of heat can be lost in the house, especially in winter. If you insulate the floor well, you don't have to worry about cold feet. Read here the steps you can take to insulate the floor.

A lack of floor insulation often leads to cold feet in winter. Especially when renovating older houses, craftsmen often find only a simple plank floor under layers of carpet and PVC. This is on a batten and the raw ceiling is already underneath. So there is no insulation to the basement. Retrofitting floor insulation can, however, easily remedy this.

Insulating floor: regulations

If you replace more than 20 percent of a component, you have to insulate according to the Energy Saving Ordinance (EnEV). Would also like to - warm feet are pleasant. But what to do if you only have 5.5 centimeters available due to the door and room height? So 5.5 centimeters for the floor insulation, load-distributing layer (screed) and covering together? Then you have to look for high-performance materials and let the building materials dealer do the math.

Selection of materials for the insulation

Start from the top: you can possibly do without the flooring. If the screed is sufficiently beautiful, it makes sense to put a fitted carpet on it.

Which screed is suitable for this? Mastic asphalt, for example, is at least two centimeters thick. However, you cannot make it yourself. It can be filled with paint and looks good, but dry screed can be laid yourself. You have to cover cement or gypsum products.

Wood-based panels (such as OSB panels) are at least 25 millimeters thick and can be painted or varnished. There are still three centimeters left. Polyurethane insulation boards are strong and best insulate (thermal conductivity level 025). These are offered, for example, by the manufacturer "Puren", are two to eight centimeters thick and laminated with an aluminum layer. Five centimeters of it are enough to meet the EnEV. Is this still not enough? Then there is only the possibility to partially insulate the basement ceiling from below.

Insulating floors: step by step

The bare ceiling must be level and clean. Unevenness can be repelled and cleaned with a spatula or chisel. Is your surface rougher than two to three millimeters? Then you can level it with self-leveling filler. Here, a powerful stirrer insert for the drill is worthwhile. Then let the mass dry first.

Roll out the release film, if the surface is still damp, the materials can expand.

Photo: Kirchner / The house

If the surface is still damp and the materials can expand differently, roll out the release film. Special edge strips should be glued to the walls all around, so that the OSB panel cannot bump into the wall later and transmit sound. The insulation boards are laid close together.

Cover the seams with self-adhesive, vapor-tight aluminum tape and lay the OSB boards over them.

Photo: Kirchner / The house

You can cover seams with self-adhesive, vapor-tight aluminum tape. Then always lay the OSB panels offset - this ensures greater stability. Then you can apply the glue and knock the panels together. Protruding edge strips are cut and a skirting board or rubber joint is attached above them.

Tip: Hard floor coverings, screed and chipboard must never hit the wall. Otherwise the sound finds a bridge and spreads out in the wall. Therefore always keep a distance of around ten millimeters.