Carpet

Trimming Carpet at Walls

Setting and running a carpet wall trimmer so the carpet tucks cleanly into the gully, with CRI 105's gully rules and Crain and Roberts settings.

Updated · 3 min read

Wall trimming leaves just enough carpet to tuck into the gully between the tack strip and the wall. Set the trimmer for the carpet's thickness, keep the blade's bevel up, and tuck the edge in without leaving backing showing.

Before you start

The gully and the stretch come first.

  • The gully should be a little less than the carpet thickness, and never more than 3/8".[1] See Tack strip installation.
  • Stretch before trimming. A power stretcher is mandatory.[1] See Setting up a power stretcher.
  • Cut the carpet with at least 3" extra at each wall for trimming.[1]
  • Keep the cushion off the tack strip.

What the standard requires at the wall

Trim without damaging baseboards or moldings. Leave enough carpet for the backing to tuck securely into the gully, with no face or backing yarns sticking out.[1] The commercial standard says the same.[2]

Set the trimmer

Most trimmers adjust blade height and throat width. Whatever the brand, keep the blade's beveled edge up.[3] With the bevel down, the tool rides up and cuts long. Make a test cut in a closet or behind a door.

Crain

  • The No. 245's best all-around setting for most carpet is the throat opening at the #2 hole and the blade height at 4 spacers.[3]
  • More spacers give a longer cut; a wider throat gives a shorter one.[3]

Roberts

  • The 10-616 is usually set on top of the fourth spacer.[5]
  • Move down if the carpet is too long, up if it's too short.[5]

Step by step

This is the standard trimmer procedure, with the same corner finish on either brand.[3][5]

  1. Two or three feet from the corner, make a 3" to 4" starter cut, leaving the excess running up the wall.
  2. Set the trimmer into the cut, flat on the carpet, with the wall runner at the floor-wall junction.
  3. Push the trimmer along the wall with one hand while pulling the excess carpet with the other.
  4. Reverse direction to finish the cut into the corner.[5]
  5. Tuck the edge into the gully with a stair tool or tucking knife.

Other trimmers

Vinyl, cushion-back and carpet tile need a different trimmer.

Crain

  • The No. 247 trims carpet and sheet vinyl. Use slotted blades for commercial loop carpet and most vinyl, and hook blades for residential cut pile and cushion-back.[4]
  • Unlike with a conventional trimmer, don't crease the material at the wall before trimming.[4]

Roberts

  • The 10-905 handles soft vinyl, carpet, carpet tile and cushion-back.[6]
  • The 10-617GT has a non-marring pad to protect walls.[7]

Tucking

Finish the edge with a stair tool or tuck knife.

Crain

  • The No. 152B stair tool is used with a mallet to tuck carpet into the corner of stair treads and into the gully between baseboard and tack strip.[8]
  • The No. 175 tuck knife has a steel blade for tucking carpet near fragile tile or toilets.[9]

Roberts

  • The 10-220 Cut and Jam cuts with one end and tucks into the gully with the other.[10]
  • 10-521 extra-wide stair tool.

Common mistakes

Most wall problems are a cut that's too long or too short.

  • Bevel down. The trimmer rides up and cuts long.
  • Trimming before stretching. The edge ends up short.
  • Gully too wide. The carpet won't hold at the wall.
  • Dull blades. They pull and fray the edge.

Tools we carry

These are the trimmers and tucking knives we stock.

References

  1. CRI 105: Residential carpet installation standard
  2. CRI 104: Commercial carpet installation standard
  3. Crain No. 245 trimmer manual
  4. Crain No. 247 instructions
  5. Roberts 10-616 trimmer manual
  6. Roberts 10-905 multipurpose wall trimmer (product page)
  7. Roberts 10-617GT carpet trimmer (product page)
  8. Crain No. 152B stair tool (product page)
  9. Crain No. 175 tuck knife (product page)
  10. Roberts 10-220 Cut and Jam (product page)

Linked PDF documents are archived copies saved by PreFloor Tools so they stay available if the publisher moves or removes them. Check the publisher's website for the latest revision.

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