Benefits of underlay - improve underfoot comfort - increases appearance of carpet and reduces flattening - absorbs the pressure of  foot traffic and reduces wear - increase sound and thermal insulation, smooths out subfloor imperfections.

It is advisable to change the underlay when buying a new carpet; as soiled, poor, and old underlay will feel hard and unwelcoming, reduce the life of carpet, cause wrinkling and premature wear spots, and may cause carpet fibres to break down more quickly. If you decide to use your existing underlay remember this may not last the life of the new carpet.  A new carpet deserves new underlay.

Below is a list and brief details of underlays that are available.  It is advisable to buy the right underlay for the right installation.  Areas with heavy traffic will need thinner but denser underlay - the combination of thickness and density is important, as a thick underlay with low density may not perform as well.  7mm or 9mm underlay is recommended for domestic use, 11mm is often used for luxury installations.

Types of underlay

Sponge rubber - a popular underlay available in flat or waffle designs in a wide range of weights for different applications.  It performs well for comfort and has durable spring retention.

PU (polyurethane) foam - a new comer to the market, typically made from recycled foam off cuts.  Excellent comfort and performance levels, with lots of thickness options. It is light weight to handle and can be re-cycled again.

Crumb rubber - it is flat and dense crumb rubber and is good for heavy footfall applications but offers less comfort but maximum protection.

Combination -  a rubber crumb base with a felt top layer.  This combination offers good protection, durability and comfort and allows carpet with seaming to bed into the top felt.

Under floor heating underlay - special underlays are available from manufacturers for use in this type of installation.  An underlay with a tog rating of 1.0 is usually used.

Felt - this traditional underlay is made from recycled fibres to create a firm, dense pad with excellent thermal insulation.