Sound Insulation for Lightweight Walls

Step-by-step plan for insulating plasterboard, wooden and system walls
This article explains how to insulate lightweight walls such as plasterboard, wooden and system walls, acoustically seperating two or more rooms from each other. These type of walls do not contain a lot of mass, and are often disconnected from the architectural ceiling in constructions that contain suspended ceilings. These are the two weak points of poorly insulating walls. Walls that consist of a timber frame with plasterboard on both sides leak noise, because of the lack of weight (mass).

Regardless of the type of wall, it must always be connected with the architectural floor, ceiling, and other walls. Therefore, the first step towards a well-insulated wall is to check whether the wall should be raised up until architectural ceiling. This has to be done in such a way that the same insulation value is reached as for the rest of the wall, because otherwise the sound leak will continue to exist! Subsequently, extra mass is added to the wall, because the heavier the wall, the higher the insulation value. We therefore recommend applying at least one layer of Isomat KE14. Whether you have to do this on both sides of the wall or do it twice at one side in order to achieve a good result, depends on the noise problem and how the rooms are being used. The Isomat products are industrial products and not intended to be applied on visible walls. That's why you have to finish the Isomat with a sheet material such as wood or plasterboard.

Step 1: Preparing the wall
Make sure that the wall is connected to the architectural ceiling, floor and other walls. Seal seams and cracks with sealant so that there are no sound leaks. Ideally, the entire wall is empty, (no sockets, radiators / central heating pipes, cable passages or other things that can cause sound leaks). Flatten out the empty wall and make it dust-free. 

Step 2: Applying glue (optional)
Whether glue has to be applied to the Isomat plates depends per situation. Optimally, at least the Isomat KE is glued onto the surface, establishing a full connection with the substrate, resulting in a sandwich construction. In case of wooden walls, glue may even be necessary, since wood is a natural product. Wooden panels may have concave and convex curves, whereas the Isomat has to touch as much surface as possible. If you don't buy glue, make sure that the finishing layer is screwed tightly.

Step 3: Applying the Isomat
Provide the side of the Isomat KE that contains jute with a layer of Stauf Extreme Tack. Do this right away for several plates so that the previous plates can dry out for a bit. Knock the Isomat firmly against the surface, preventing air bubbles from emerging. It can be the case that the glue does not immediately provide enough adhesion to keep the 14 Kg heavy plate on its place. To facilitate this, fixiate the Isomat with a nail or staple the plates to prevent them from falling off the wall. If you are with multiple people, a second person can also immediately apply a finishing layer such as plasterboard or a wooden plate on top of the Isomat. This layer is installed by screwing through the Isomat. It may be the case that the Isomat plates do not contain perfectly perpendicular angles, which sometimes results in a small seam between two plates. But this has no significant influence on the end result.

Step 4: Finishing the wall
After the finishing layer has been applied, inspect the wall again for sound leaks in the form of seams and cracks, which should be sealed. Avoid making holes in the wall as much as possible (for example for pipes or cables). You will find an acoustic cable passage from Roxtec in our webshop. 

Would you like personal advice? 
Please contact us, we will be happy to answer your questions as soon as possible.