Insulation of the attic with polystyrene boards

Insulation of the attic with polystyrene boards

The groove and tongue facilitate assembly. The white foam is easy to lay and fits on any surface.

The proposed method of wall insulation is simple, clean and does not require special skills and workload. The boards of this system can be laid indefinitely. They can be adapted to any arrangement of construction beams (rafters); they are stiff enough, that even with gaps 1,5 meters are easily wedged between the elements of the roof structure. The boards of the Styrotect S system are stiff and do not deform and – most importantly – they are waterproof. As a result, it is not necessary to make a waterproofing insulation, (which, among other things, protects the insulating layer from getting wet).

Nevertheless, we recommend placing a polyethylene film between the boards and the wall formwork. The foil will allow for additional sealing of any inaccuracies and will protect against penetrating wind and dust. However, from the inside, we can finish with paneling, panels, gypsum boards, etc.. It is important to – as with any other insulation – airing on the back of the insulation layer. In this case, a gap is sufficient 2 cm.

If we intend to unfasten the material under the roof sheathing, which could hang slightly downwards, we should leave a little more space for ventilation – even approx 4 cm.

We start the installation of insulation from the bottom

Roof insulation is only effective then , when the air circulates freely within the ridge and eaves after installing the insulation, ensuring ventilation of the insulating layer and the roof sheathing. We always start arranging the boards from the bottom. The pen must point upwards. Because with the exact matching of the boards, we will not avoid cutting them, we advise you to prepare a cardboard template beforehand, which will reflect the angle of the roof slope. Using such a template, it will be possible to properly cut the insulation boards and fit them to each fragment of the roof. Nawet przy zachowaniu największej dokładności i precyzji może się zdążyć, that one of the matching cuts will fail. We shouldn't throw away the entire CD at once, because the resulting gaps can be filled with mounting foam (np. Compactol). If we want to take out one of the boards, put putty on the left and right side by the rafters and, pressing slightly, pull out a fragment of the insulation.

Method of mounting polystyrene boards:

The boards will fill exactly the gap between the rafters, when they will be Fr. 1 % wider than the dimension between the rafters. Thanks to this, they will get stuck between them and no gaps will be created.

Laying the boards is very easy thanks to the tongue and groove joints. The severed end is the start of the next element.

Connecting elements to each other is simple. The plates must be pressed in like this, so that they do not protrude above the rafter plane and shifted downwards, so that the groove goes into the tongue of the previously installed board. Then the insulation layer is almost perfect.

Insulation with rigid foam: behind the paneling there is 14 a centimeter thick layer of polystyrene. The slats of the roof cover create a distance to the tiles.


Oil-based solvents and wood preservatives may react with Styrotect “S”. However, it is enough to wait for time, when everything is completely dry. In any case, the manufacturer's recommendations should be followed, which are located on the packaging.