Cutting Seams with Row Finders and Seam Cutters

A seam can only be as good as the edges you cut. On most carpet, that means following the rows rather than a straightedge. Row finders open the row; seam cutters follow it.

Row-cut when you can

Row-cut edges are preferred, but trimming too far into patterned carpet throws off the pattern match (section 10.1).^[1] Some commercial guides go further. They call for row-cutting every seam except printed patterns, and advise against overlap or double-cut seams.^[2]

Cut pile vs loop pile

The technique changes with the construction.

• Cut pile: open the row with a row finder, then run a seam cutter or row-running knife down it. Cut with the direction of the nap.^[4]
• Loop pile and berber: cut between rows with the cutter's nose in the row. Don't let the guide bar cross a row.^[3]
• Trace cut: overlap about 1" and cut the bottom piece using the top edge as a guide.

Choosing a row finder

Row finders come in two main styles.^[4]

Use a top-cutting blade to cut from the face, or a trimmer blade to cut from the back.

Seal the edges

Seal every seam (section 10.2).^[1]

• For hot-melt seams, seal the cut edges before seaming. See Hot-melt seaming.
• For glue-down seams, run the bead on one edge only and join the edges while it's wet.^[1]
• Some commercial guides specify a continuous 1/8" bead.^[2]

Pattern match

On patterned carpet, match the pattern at the middle of the seam (section 16.6) and work out toward the ends.^[1]

Step by step

Do both pieces the same way, one full length at a time.

1. Check pile direction. Both pieces must lay the same way.
2. Open the row with a row finder along the full length.
3. Cut down the row with the seam cutter, keeping the guide in the row.
4. Repeat on the second piece.
5. Butt the edges and check for gaps or overlap before seaming.
6. Seal the edges as the seaming method requires.

Common mistakes

Most visible seams start with the cut.

• Cutting across rows. The seam wanders and shows.
• Cutting against the nap.
• Skipping edge sealing. Edges fray and the seam opens.
• Matching pattern at one end. The mismatch builds toward the other end.

More in Peaked and visible seams.

Tools we carry

These are the row finders and cutters we stock.

• Crain 366 Row Finder, Crain 367 Residential Row Finder, Roberts 10-517 Row Finder
• Roberts 10-152GT Loop Pile Cutter and Crain No. 300 Loop Pile Cutter
• Crain No. 301 Cushion Back Cutter
• All seam cutters and row finders

References

1. CRI 105: Residential carpet installation standard
2. Beaulieu/Peerless: Carpet installation guide
3. Roberts 10-154 loop pile cutter instructions
4. Crain: Seam cutters and row finders

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