Defra Laminate Floors Project Summary

A variety of laminate and wood floors were tested for impact sound transmission with and without underlays. Testing was also undertaken on carpets on the same floors. Three core floors were tested: a concrete floor, a basic timber floor (worst case) and a timber floor with a pre-installed resilient floating floor system. Using the laminate floor finish (with no underlay) as the index to compare against other treatments, the following table highlights the problem when carpet is replaced by laminate or wood floors.
• The introduction of an underlay on a timber separating floor with a pre-installed floating floor treatment will not alter the overall performance due to the floating floor controlling most of the impact sound transmission. However, from the frequency analysis it does improve the mid and high frequency response.
• A laminate / wood floor with underlay provides a slight improvement over a basic timber floor although a more significant improvement is achieved on a basic concrete construction.
• The removal of carpets and underlay on a basic timber floor, as with plain sanded floor boards, results in a 21dB increase in impact sound transmission.

In respect of the Building Regulations, it was concluded that the minimum regulatory impact performance requirements across all UK countries are less onerous than those European countries considered although the pre-1985 AAD criteria were comparable to current French and Danish requirements although the Norwegian and German requirements are significantly more stringent.
The specifications for underlay materials given in the Building Standards documents for use with Type 1 concrete floors are provided as either a minimum 4.5 mm thickness or as a minimum performance criterion, ∆Lw 17 dB. It was shown (attached figure) that this measure is not equally applicable for timber floors or once hardwood flooring is laid. The ∆Lw criterion, which is determined from impact measurements made on the resilient material, significantly overestimates the actual performance improvement when used under a hard floor finish, with final impact sound performance limited to 5 dB and 23 dB for the basic timber and concrete floors considered.

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