Step-by-step plan for the acoustic and thermal insulation of a wooden roof boarding.

Step-by-Step Plan for Insulating Your Roof

Insulating the wooden roof boarding

Overall, there are two roof types, roofs containing PIR panels and the traditional roofs with a wooden boarding. In both cases the roofs allow a lot of noise to enter in from outside. This has to do with the lack of weight of a standard roof, allowing sound to easily enter. In the following step-by-step plan, you can read how to improve the sound insulation of your roof by adding weight to your roof boarding.

The roof boarding that is depicted in picture 1 turned out to be entirely empty. As a result, it is cold during the winter, hot during the summer and during all seasons you suffer from noise nuisance. The lack of mass and the absence of insulating filling cause these issues. The solution, however, is surprisingly simple.

Roof boarding without insulation material

Step 1: Sealing seams and cracks

The first step from this plan: seal the seams and cracks, because they cause warmth and sound to leak. As for bigger cracks, we recommend using PUR foam, for the smaller ones you can use silicon sealant.

Step 2: Filling the cavities (traditional roof)

The second step of the solution, depicted in picture 2, is filling the cavities with Acoustiwool (in case there are cavities of course, depending on the type of roof). Avoid empty holes by any means, because they allow sound and cold air to enter in. If necessary, vapor penetrable foil can be applied to the roof boarding, making sure condensation problems won’t arise in the future. Then, the spaces between the beams are at least for 80% filled with Acoustiwool. Acoustiwool is a polyester wool-based product, it doesn’t itch when using it and it insulates both acoustically and thermally. Subsequently, an extra wooden strip is added to the frame in order to facilitate mounting plasterboard during a later step (step 4), plus the filling remains in place.


The roof boarding equipped with Acoustiwool, polyester wool

Step 3: Placing the first layer of plasterboard (traditional roof)

The third step consists of adding a first layer of plasterboard. This layer is meant to cover the roof boarding. It protects from the cold and serves as a substrate for the sound insulation material Isomat KE (step 4). Sound insulation revolves around adding mass to the construction. Plasterboard adds mass, regulates moisture, and is fireproof. Make sure that the plasterboard connects well to the walls and the construction. Tip: pay extra attention to the connection in case of a rough wall, because a rough wall contains a lot of small cracks. Seal them with silicon sealant.

De eerste gipsplaat is aangebracht over de Akoestiwol.

Step 4: Placing the sound insulation (traditional roof, PUR panel roof)

This step consists of applying the sound insulation material Isomat KE (type 14 kg/m2, 5,7 mm thick). This soundproofing mat significantly increases the level of sound insulation due to its weight and tightness and causes the roof boarding to be firmer. At one side, this type of Isomat KE contains jute, which makes it harder to attach it using glue. Provide the side of jute with Stauf Extreme Tack, you will need approximately 0,3 kg per m2. Let it dry for a short moment. After 5 to 10 minutes you can mount the Isomat KE to the plasterboard or the PUR panel. To this end, additionally use screws, since Isomat won’t stick by itself due to the high weight.

Plasterboard equipped with sound insulating Isomat KE

Step 5: The finishing layer

As for the last step, we apply a finishing layer on top of the Isomat KE in order to hide it from sight. This can be carried out in two ways: either by installing another layer plasterboard or by using another finishing material like multiplex, laths, carpet, etc. Make sure that no seams and cracks are left after applying the finishing layer, preventing sound leaks.

Isomat KE, finished with plasterboard, ready to be stuccoed

A sucessful project

The reaction of our client that gave us these pictures: “Our sleeping room has successfully been insulated against airplane noise”.

Questions? Contact opnemen

Please feel free to contact us, we will be happy to answer your question as soon as possible.