Rubber carpet cushionThere are two basic types of sponge rubber carpet cushion:
Waffled rubber carpet cushion is made by molding natural or synthetic rubber. Heat cures the rubber and forms a waffle pattern. This variety produces a soft, resilient cushion whose luxurious feel is particularly useful for residences.
Flat sponge rubber is a firm, dense carpet cushion which has a flat surface and is normally used in large-scale commercial applications and with loop type (or Berber) carpet.
Rubber carpet cushion manufacturing processes can be varied to produce different levels of density and firmness. The usual measurement is the weight in ounces per square yard.
Fiber carpet cushionFoam and rubber carpet cushions are produced from new and recycled materials. Fiber carpet cushion, on the other hand, uses existing fibers (both virgin and recycled, and either natural or man-made fibers) which are interlocked into a useful sheet of felt. There are two distinct varieties of fiber carpet cushion:
Natural fibers include felt, animal hair, and jute (the material used to make some kinds of rope and heavy burlap bags). This is one of the oldest types of carpet cushion, dating back to the earliest days of machine-made carpet.
Synthetic fibers include nylon, polyester, polypropylene, and acrylics, which are needle-punched into relatively dense cushions which have a firm feel and, as with other types of carpet cushion, can be made in virtually any weight, to stand up under light, medium, or heavy traffic, which is how they are usually classified.
Special notesBerber carpet is becoming increasingly popular and needs a thin, firm carpet cushion. When buying this type of carpet, be sure that the accompanying cushion has been specified by the manufacturer as suitable for Berber carpet.
Radiant heating is becoming more widely used in certain sections of the country. In the case of radiant heating, you do not want a carpet cushion which is an exceptionally effective insulator, but one which allows the heat from the subflooring to penetrate the carpet system and heat the room. A relatively thin, flat cellular sponge rubber or synthetic fiber carpet cushion works well under these circumstances.