Installing Timber Flooring with an Acoustic Underlay

In the market there are many products and many systems that range from thin foam underlays, applied products that provide acoustic benefits, and various shapes and thicknesses of often rubber-based underlays. Some are applicable to floating floor installations while others are for stick-down applications.

With the acoustic performance of floor systems, there are some general principles to consider, as follows:

• Acoustic underlays are manufactured from different materials and are of different profiles and densities, but the thickness from different suppliers is frequently the same. Even though the thickness of the acoustic underlay may be the same, there can be a significant difference in the performance of one product compared to another.
  
  

• The concrete slab thickness has a significant effect with 175mm thick slabs often having a sound transmission of about 70dB but 150mm thick slabs about 80 dB. Usually, strata committees have paid to have professional testing done on the floors and have used that to inform the minimum standards for acoustic underlay usage in the building.
  
  

• Some timber flooring systems have been manufactured to include an acoustic underlay. These are rarely sufficient to meet the minimum standards of most strata committees. However, they may be appropriate for the second floor of a residence and other situations.

Acoustic underlays come in different densities and materials to cater to all flooring types. It’s also important to understand that higher or lower density does not necessarily relate to performance characteristics. Also, if you are having parquetry installed, there are some specific underlays that have been designed especially for that purpose.

With floating floors, underlay selection can have a profound effect on the ‘reflected’ noise heard when walking across the floor. Some underlays are very good at achieving both a quiet floor to walk on and a solid feel underfoot, while with others the floor will be very hollow sounding.

Solid timber floors often require an intermediate layer of plywood between the flooring and the acoustic underlay. This is to ensure that the durability of the installation against the usual changes in heat and moisture in a room will not be affected by the addition of an underlay.

This is particularly important with heating and cooling being used in the room, as well as locations close to the coast.

At times, it is possible to affix the timber floor directly onto the underlay product with glues. However, some underlay products are not designed for this purpose, and in many cases, manufacturer warranties and performance warranties may actually be voided if this is done. This is why it is important to work with experts such as Know-How Flooring who are well-informed about the performance characteristics and the recommended usages of every material they recommend.

If, instead of using a floating floor, your property is using a self-leveling compound as a subfloor with the timber flooring product glued on top as mentioned above, there are several evaluations and preparations that need to be done before installation.

This includes the slab surface being sound, and the slab being flat, dry, and free from contaminants that can affect adhesion. Moisture vapor barriers may also be necessary. Greater care and attention are necessary for the preparation to ensure that the required bond strength is achieved and to minimize possible dummy spots.