How to soundproof a wooden floor

How to soundproof wooden timber floors
In this guide you learn all there is to know about how to soundproof a wooden floor. With that we mean a wooden timber supporting floor. The soundproofing properties of a wood timber floor is not that great. Airborne sound and impact noise are perceivable underneath the floor and in adjacent rooms. In the images below you can see a typical wooden floor on a construction of wooden beams, finished with simple sheet of plywood. In older houses these are often (creaking) planks. The weaknesses of a wooden timber floor is the lack of mass (weight) and stiffness. Lets start the guide on 'How to soundproof a wooden floor'.

Soundproofing impact noise
In this guide, reducing impact noise is not the main goal, but we have a solution and product, as you can imagine. Soundproofing impact noise is achieved by applying one layer, or a double layer for an even better result, of Regupol Comfort on top of the wooden timber floor. Regupol Comfort is a vibration insulating material that reduces impact noise, caused by, for example, sliding chairs. Next step is adding a layer of reinforced gypsum floor boards (or similar) on top the Regupol. Use a double layer when you also use a double layer of Regupol. Make sure that layers of gypsum boards don't the walls, this will avoid impact noise. Seal the gap between the walls and the gypsum boards with a sealant.

Soundproofing airborne noise from a wooden floor
Soundproofing airborne noise, what this guide is all about, is achieved by providing the floor with a sound barrier, a mass loaded vinyl sheet, such as Isomat KE. The more mass you add, the heavier the floor, the better the soundproofing result. The thickness of the floor is not relevant, the mass on the other hand is!

To soundproof a wooden floor against airborne noise, we recommend using Isomat with a weight of 14 kg/m². Isomat KE is a mass loaded vinyl sheet with a thickness of only 5 to 6 mm. Ideal to soundproof rooms with a low ceiling. Generally speaking, the load-bearing capacity of the floor can handle the extra weight of the Isomat. Do you have any doubts about this? Than inquire a contractor or architect that knows the load-bearing capacity of the wooden floor.

Products to soundproof a wooden timber floor
Products and soundproofing materials needed for soundproofing a wooden floor:

• Isomat KE 
  We recommend Isomat KE 14 kg/m² for the best result.
• Stauf Extreme Tack
  Paste glue that is easy to spread, virtually odourless.
• Isotape Alu
  For sealing seams and cracks (optional).

To take care of yourself:

• Glue comb, for applying Stauf glue.
• Hobby knife, to cut the Isomat sheets.
• Sealant, for sealing cracks and seams.

 
Step 1: The preparation
When all floor coverings have been removed, the wooden floor to soundproof is visible. First, the floor should be inspected to detect loose floor boards. Fix them so the floor is flat and stops creaking. Next, make sure that there are no seams and cracks to avoid sound leaks. This is important for the end result. Seams and cracks can be sealed with sealant. Larger cracks can be closed with pieces of filler wood. Make the floor dust-free for the bonding of the Isomat with the Stauf glue.

Isomat glued with Stauf Extreme Tack

Step 2: Apply and process Isomat
The Isomat sheets can be fixed by a thin layer of glue or stapling them. Press Isomat tightly against the walls and/or skirting boards. In fact, this should fit tightly and seamlessly against the walls or skirting boards to prevent sound leaks. Gluing the sheets is not always necessary. You equip the entire Isomat board with glue if you have a floor consisting of planks, and about 70% if you have a smooth plywood or underlayment floor (see photo).

The paste-like glue is easy to apply and spread with a glue comb, using a Stauf bucket of 3.5 kg you may be able to cover about 5 to 6 m² (depending on the application). Press the plates firmly in place, so that a good adhesion is achieved. At room temperature Isomat is supple and forms somewhat to the subsurface. By walking over the sheets with small steps they get well pressed and formed.

Isomat sheet applied on the floor and the walls

Step 3: Seams and cracks
Seams and cracks should be sealed, for example along the skirting boards and walls and the seams between the Isomat sheets. The sheets of Isomat will not be 100% perpendicular, and probably the walls won't be either, causing some seams may rise. When the entire floor is equipped with Isomat, it is advisable to cover the seams with Alu Finishing Tape (see image).

Seams and cracks sealed with Alu Finishing Tape

Step 4: Finish
Now that the wooden floor is equipped with Isomat, you will notice to floor feeling more solid. This will improve further when the glue is dried and the Isomat sheets are more set. In this example light grey carpet tiles are used directly on the Isomat. If you want to reduce impact noise you can add a layer of plywood on top of the Isomat. Use screws to fix the plywood to the floor underneath. By applying a soft floor covering, sounds of footsteps will also be less noticeable in the room below.

Isomat KE finished with carpet tiles

Result
The wooden floor we based this guide on is in a house that was build in the sixties, a simple basic timber floor finished with some plywood. Airborne sound, such as voices and music, were poorly insulated. Voices from lower rooms were perceived as hums, but after soundproofing the floor with Isomat, noise sounded as if it came from much further away. Unfortunately, nobody can guarantee an end result, but in many situations this method of soundproofing will result in an noticeable improvement, in most cases a reduction of 8 decibels can be achieved. 

Questions? 
Do you have questions about how to soundproof a wooden floor? Please let us know, just send us an e-mail, we are happy to help!