Most residential carpet is installed over a separate cushion that makes the carpet softer and more resilient underfoot, reduces noise, provides a little thermal insulation and prolongs carpet life. Cushion may be made from any of several materials, including various types of natural and synthetic fibers and urethane. Density--not thickness--is most important. A carpet that is too thick over-stresses carpet backing and is too soft underfoot.
The Carpet and Rug Institute recommends a maximum thickness of 7/16-inch for residential carpet. If the carpet has a lower pile height, such as a berber or a commercial-like cut pile, the cushion should be even thinner--3/8-inch or less. But it should be firm and resilient. FHA minimums are 6-pound cushion under standard residential cut pile and 8-pound cushion under a thinner berber or low pile. Expect to pay about $2.50 per yard for quality cushion.
Ask your carpet retailer for a Class 1 cushion for moderate traffic areas and a Class 2 cushion where there will be heavy traffic, such as stairs, hallways and family rooms.
--Don Vandervort
