Benefits of underlay

Good underlay will:

• improve underfoot comfort
• increase appearance retention, reducing flattenning
• absorb the pressure of foot traffic and reduce wear
• improve thermal insulation and warmth
• increase sound insulation
• smooth out sub-floor imperfections
• last the lifetime of the carpet

Poor or old underlay will:

• feel hard and unwelcoming
• reduce carpet life
• cause wrinkling and premature wear spots
• cause carpet fibres to break down more quickly
• not meet British standards

Thickness of underlay

Underlay should be a maximum of 12mm (working with grippers will be difficult if it is any thicker) but rooms with heavy use will need a thinner, denser pad. The combination of thickness and density is al important as a thick underlay with low density is all important as a thick underlay with low density may not perform well. Typically, the thicker the underlay, the better quality it will need to be. 11mm is often used for luxury installations with 9mm and 7mm the common for domestic thickness.

Types of underlay

• Sponge rubber – this is the most popular underlay available in flat or waffle patterns in a wide range of weights for different applications. It performs well for comfort and has a durable spring retention.
• PU (polyurethane) foam – PU foam is made from recycled foam offcuts. The foam provides excellent comfort and performance levels with lots of thickness options – and its light weight helps handling. The product can be recycled again after use.
• Crumb rubber – flat and dense, crumb rubber is good for heavy footfall – offering maximum protection but a little less comfort (and very good over stair nosings).
• Laminate underlay – this improves the acoustic performance of the floor and helps the boards float above any imperfections in the sub-surface.
• Combination – a rubber crumb base with a felt top layer offers a good combination of protection, durability and comfort. It also allows carpets with seaming to bed into the top felt.
• Underfloor heating underlay – Always ask if there is underfloor heating. Most manufacturers offer specialised products. Underlay and carpet with a combined tog rating up to 2.5 can be used – which means the underlay would normally have a tof rating of 1.0.
• Felt – this traditional (but environmentally friendly) underlay is made from recycled fibres – wool, jute and synthetic – to create a firm, dense pad with excellent thermal insulation. Still a very popular choice when used with stretch lifting woven carpets.
• Pre-tackified underlay – a self-adhesive single stick underlay in both needlefelt and PU. A removable system for heavy use when comfort is desired.