Guide · For the trade
Carpet pad types: the best carpet pad for each construction, and how to read the spec
The best carpet pad for a residential cut pile is 7/16 inch, 8 lb density rebond; the best pad under Berber, loop, Wilton, Axminster and any stair runner is a dense, thin pad, 1/4 to 3/8 inch, in felt, rubber or a 32 oz synthetic fiber. Thicker is not better: a pad over 7/16 inch lets the carpet flex, breaks the backing and opens seams, and most mill warranties name a maximum thickness and a minimum density. The pad is specified by three numbers, thickness in inches, density in pounds per cubic foot or weight in ounces per square yard, and type.
This guide is for the designer writing the pad line on a carpet spec, and for the junior who has been told "just use the 8 lb" and wants to know why. It covers the carpet padding types, what the numbers mean, rebond vs felt, which pad goes under which carpet, and what to tell the installer. Stairs have their own rules in the carpet pad for stairs guide, and slabs and basements are in the moisture barrier pad guide.
The three numbers on a pad spec
Thickness is in fractions of an inch: 1/4, 3/8, 7/16 and 1/2 are the common gauges. Density, for foam pads, is pounds per cubic foot: 6 lb is soft, 8 lb is the residential standard, 10 lb is firm. Felt, fiber and rubber pads are rated by weight in ounces per square yard instead, 32 to 40 oz for felt and up to 100 oz for flat rubber. The third line is type, and that is where most specs go wrong: a thick soft pad under a loop carpet feels luxurious on day one and wrinkles the carpet by month six.
Carpet padding types, on one sheet
| Pad type | What it is | Usual spec | Best under | Keep it away from |
|---|---|---|---|---|
| Rebond | Bonded scrap polyurethane foam, multicolored | 7/16 in, 8 lb; 3/8 in, 10 lb for firmer | Residential cut pile: plush, Saxony, frieze, textured | Loop, Berber, woven carpet, stairs, commercial |
| Prime and frothed urethane | Virgin foam, uniform cell, frothed is the denser version | 1/4 to 7/16 in, 8 to 12 lb | Cut pile where a firm, even feel is wanted; frothed under loop | Cheap low-density prime grades under heavy traffic |
| Memory foam | Visco-elastic urethane | 7/16 in | Bedrooms with a thick cut pile | Any room with furniture that moves, any loop |
| Felt and synthetic fiber | Needle-punched jute, wool or synthetic fiber | 1/4 to 3/8 in, 32 to 40 oz | Berber, loop, Wilton, Axminster, wool broadloom, stair runners | Below-grade slabs unless synthetic |
| Rubber | Waffle (air pockets) or flat slab rubber | Waffle 3/8 in, 64 to 90 oz; flat 1/4 in, 100 oz | Flat rubber under woven and loop carpet, stairs, hospitality; waffle under cut pile | Radiant heat without checking the mill, flat rubber where cushion is wanted |
Moisture barrier rebond, a rebond with a sealed film on top, is a sixth option for slabs and clients with pets; it keeps spills out of the pad but does nothing for a damp slab. The Carpet and Rug Institute's residential cut pile guidance is a maximum of 7/16 inch at 6 lb or more; woven and loop carpet calls for 3/8 inch or thinner and denser.
Rebond vs felt: the choice that matters most
Rebond is soft, springy and inexpensive, and it is right under a tufted cut pile in a bedroom or a living room. The spring is the problem under anything else: a loop pile, a Berber, a Wilton or an Axminster stretches over a soft pad as it flexes, the backing cracks and the carpet ripples. Felt and fiber pads do not compress, so the carpet stays flat, seams stay shut, and the pile wears instead of the backing. Under wool broadloom, woven or dense-tufted in most of our 1,397 wool styles, felt or flat rubber is the pad to specify. When a client wants the woven carpet and the soft feel, the honest answer is that they are choosing between the two.
Best carpet pad by carpet construction
- Tufted cut pile, nylon, triexta or polyester, in a bedroom or living room: 7/16 inch, 8 lb rebond. The nylon broadloom from Masland, Milliken and Fabrica is specified this way nearly every time.
- Tufted cut pile in a hall or family room: 3/8 inch, 10 lb rebond or 8 lb frothed urethane. Firmer and flatter where feet turn.
- Berber and loop, patterned loop, cut-and-loop: 1/4 to 3/8 inch, 32 oz or heavier felt, or a frothed urethane at 10 lb or more. Never a thick rebond.
- Wilton and Axminster woven wool, and most wool broadloom: 1/4 to 3/8 inch felt or flat rubber, 32 to 40 oz.
- Stair runners and stair carpet: 1/4 to 3/8 inch dense felt or flat rubber, cut and placed per the stairs guide.
- Commercial and hospitality: 1/4 inch or thinner dense pad, double-stick, or no pad under a direct glue; the mill's commercial spec governs.
What is the recommended thickness for carpet padding?
For residential cut pile, 7/16 inch is the usual maximum and the most common spec; 3/8 inch is the better choice where the pile is dense or the room is busy. For loop, Berber and woven carpet, 1/4 to 3/8 inch. For stairs, 3/8 inch at most. Anything thicker than 1/2 inch is outside most mill warranties. Thickness also changes the finished floor height at thresholds, transitions and stair nosings; tell the installer the gauge before the trim is set.
What to tell the installer
Write the pad on the spec with all three numbers and the type, name the carpet construction, and send the mill's installation sheet. Ask for the pad seams to be staggered from the carpet seams and taped, with the moisture barrier film up if there is one, for a moisture test on any slab, and for stairs to get their own pad cut per tread. If the carpet is woven wool, ask the installer to power-stretch it over a firm pad.
Questions designers ask
What is the best carpet pad for most residential jobs?
A 7/16 inch, 8 lb rebond under tufted cut pile, and a 1/4 to 3/8 inch felt or flat rubber under loop, Berber, woven wool and stairs. Specify by construction, not by room, and the answer is nearly always one of those two.
Is a 6 lb or 8 lb carpet pad better?
8 lb. The 6 lb rebond is the minimum most mills accept, and it bottoms out in a traffic lane within a couple of years, after which the backing takes the wear. The 8 lb holds its feel for the life of the carpet; a 10 lb is firmer still and right in halls.
Which carpet backing is best?
For tufted carpet, a woven polypropylene secondary backing (ActionBac is the common trade name) is the standard to specify over a cheaper non-woven; felt-backed carpets are a touch quieter. Woven carpet, Wilton and Axminster, has no secondary backing to choose; its construction is the backing, which is why it needs a firm pad.
What is the most durable type of carpet?
For the construction, a dense woven wool or a dense loop nylon; for the fiber, nylon in a solution-dyed grade, then wool. Durability is density and pile weight more than fiber, and the pad matters as much as either: the same carpet over a firm pad lasts years longer than over a soft one.
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