Carpet

Choosing Carpet Pad

Choosing carpet cushion by density, thickness and type: CRI limits, Carpet Cushion Council minimums, mill warranty specs, berber and radiant heat.

Updated · 3 min read

Pad is chosen by density and thickness, and the carpet maker's warranty sets the limits. Firmer beats thicker. CRI caps residential cushion at 7/16", and berber needs a thin, firm pad.

Quick answer

For most residential cut pile, a 7/16" bonded (rebond) pad of at least 6.5 lb meets CRI 105, the Carpet Cushion Council's heavy-traffic minimum and the major mills' warranties. For berber, use a thin, dense pad. For commercial, stay at 3/8" or less.

The limits

Standards and mills don't all agree, so pick a pad that meets every one of them.

Standard or warranty Thickness Density (bonded urethane)
CRI 105 (residential) Not over 7/16" Per the carpet maker[1]
CRI 104 (commercial) Not over 3/8" Per the carpet maker[2]
Carpet Cushion Council, residential 3/8" minimum, 1/2" maximum 5.0 lb (Class 1), 6.5 lb (Class 2: heavy traffic and all stairs)[3]
Mohawk warranty 3/8" to 1/2" At least 5 lb[7]
Shaw warranty Maximum 1/2" recommended Must meet FHA/HUD[8]

Ignoring these cushion recommendations can void the carpet warranty.[1] The CCC residential minimums are the ones HUD adopted for FHA-financed housing.[3]

How to choose

Work through these for each job.

  • Traffic: CCC Class 1 covers living rooms, dining rooms and bedrooms. Class 2 covers heavy traffic and every stair installation.[3] Firmer cushion works better on stairs, in halls and under heavy furniture.[9]
  • Berber: berber needs a thin, firm cushion.[9] Mohawk calls for at least 8 lb, 1/4" to 3/8" thick, under berber.[7]
  • Radiant heat: most radiant system makers want the combined R-value of carpet and cushion at 4.0 or less, and thinner cushion works better.[6] Bonded urethane rates about R-1.7 at 7/16" and R-1.0 at 1/4".[10]
  • Commercial: CRI 104 and CCC cap commercial cushion at 3/8".[4]
  • Moisture and pets: pads with a moisture barrier go barrier side up.[5]

Installing the pad

Lay the pad to the installation standard and the cushion guidelines.[1][5]

  • Run cushion in the longest lengths possible, with seams at right angles to carpet seams or offset at least 6".
  • Bonded cushion goes smooth (scrim) side up. Rubber cushion goes textured side down.
  • At the tack strip, CRI says trim cushion flush with the strip;[1] the cushion council says leave about a 1/4" gap.[5] Either way, it must not ride up on the strip.
  • Staple or glue seams and the perimeter, and tape seams. See Tack strip installation.

Our pads against the limits

Our pad titles give density and thickness.

  • All our 7/16" pads are at the CRI 105 residential maximum. Our rebond pads are above the CCC Class 1 minimum for bonded urethane, and the 8 lb and 10 lb pads also exceed the Class 2 minimum for stairs and heavy traffic.
  • The 8 lb 1/4" pad fits Mohawk's berber spec and suits radiant heat.
  • For commercial jobs, 7/16" is over the 3/8" limit.

Common mistakes

Most pad-related claims come from one of these.

  • Thick, soft pad under berber. Cushion that's too soft hurts how the carpet performs.[7]
  • Thicker than the maximum. Cushion that's too thick keeps the carpet from anchoring properly.[7]
  • Pad up on the tack strip.
  • Thick pad over radiant heat.

Pads we carry

These are the pads and the knife for cutting them.

References

  1. CRI 105: Residential carpet installation standard
  2. CRI 104: Commercial carpet installation standard
  3. Carpet Cushion Council: Residential cushion specifications
  4. Carpet Cushion Council: Commercial cushion specifications
  5. Carpet Cushion Council: Installation guidelines
  6. CRI: Carpet and heated floors
  7. Mohawk: Residential carpet warranty
  8. Shaw: Residential carpet warranty
  9. Carpet Cushion Council: Cushion types
  10. Carpet Cushion Council: R-values

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