If you decide to float your bamboo flooring over an underlay then you must decide which type of underlay suits your needs. An underlay is a thin layer of cushioning which is laid between the subfloor and the bamboo floor. Underlays are typically used for either sound insulation or thermal resistance. There is also a special type of underlay which is compatible with underfloor heating.
Underlay for thermal resistance
Underlays used for thermal resistance are measured by a tog rating. The higher the tog, the better the heat insulation. For bamboo flooring it is recommended that an underlay with a rating of approximately 1.0tog is used.
Underlay for sound insulation
Sound reducing underlays are measured by the decibel (dB) rating, with the higher the dB rating the more sound-proofing they provide. For bamboo flooring, a good quality underlay should have a rating between -19dB and -25dB. An ideal underlay which offers both heat insulation and sound reduction is our Silver Bam Underlay.
Underlay suitable for underfloor heating
If you have an underfloor heating system then you need to ensure that the underlay you use has a low tog rating (such as 0.35tog), to allow the transfer of heat through to your flooring. It is important to remember that the colour or thickness of the underlay has no relationship to the amount of thermal resistance or sound proofing – these are measured purely by tog and decibel ratings.
Also, please note that underlays should never be used to level out an uneven subfloor, or to provide a barrier to moisture from the subfloor. Products such as a floor levelling compounds and Damp Proof Membranes (DPM) are available for these specific problems.