How to Cut and Seam a Carpet

Installer Joining Two Carpet Pieces with Iron

BanksPhotos / Getty Images

Overview
  • Working Time: 2 hrs
  • Total Time: 8 hrs
  • Yield: One 10-foot carpet seam
  • Skill Level: Advanced
  • Estimated Cost: $5 to $10 for seam tape

Carpet installation is not a very common do-it-yourself project, mostly because professional installation is quite affordable. Carpet prices may even include the cost of installation. But for those DIYers who do try it, the trickiest part of carpet installation is creating seams between butting pieces of carpet. Standard carpeting is typically sold in 12- and 15-foot wide rolls, which means that carpeting large rooms will usually require that you use two pieces and seam them together.

Seaming carpet like a pro requires precise cuts and proper seaming technique using heat-activated carpet seaming tape and a seaming iron. The key to a tight-fitting, professional-looking seam is to start with a double-cutting technique that matches the two edges perfectly. 

Seaming a Carpet

Few homeowners will have any need to own the specialty tools required for seaming a carpet, such as the seaming iron and seam roller. These tools can be leased at the same tool rental outlets and home centers where you lease the carpet stretcher and other tools required for DIY carpet installation. The carpet seam tape you'll need can be purchased from home centers and online retailers.

Seaming normally occurs after the carpet pad and tackless strips are installed. Seaming occurs as the carpet pieces are being cut to the rough size but before stretching and final trimming occur. The seams must be secure before the carpet is stretched out over the perimeter tackless strips and trimmed to fit along the baseboards.

When to Call in a Pro

Carpet installation—and seaming in particular—can be a somewhat tricky project for DIYers, especially beginners. A poor job seaming a carpet results in a haphazard appearance that you'll have to live with for a long time. Considering that professional carpet installation typically adds less than $1 per square foot to the overall cost, many homeowners who attempt to install a carpet with seams resolve never to do it again.

But a DIYer on a very tight budget, or one who likes the challenge, can indeed install a seamed carpet with professional looking results. It's regarded as an advanced project, suitable for advanced DIYers who are patient and willing to take a bit of a risk.

What You'll Need

Equipment / Tools

  • Tape measure
  • Pencil
  • Chalk line
  • Straightedge
  • Carpet knife or utility knife
  • Carpet seam roller
  • Books or other heavy objects
  • Carpet seam iron

Materials

  • Scrap board or strip of plywood
  • Carpet seaming tape

Instructions

  1. Position the Carpet Pieces

    Lay out the two carpet pieces side by side so they overlap by about 3 inches. Make sure that the pile is facing the same direction in both pieces. If you are unsure, check the back of the carpet for arrows indicating the direction of the pile.

    Person Laying Out Carpet.
    Courtesy of TrendTreasures Inc.
  2. Mark and Cut the First Edge

    Roll back the top piece of carpet. On the backside, measure 1 inch in from its outer edge and mark the backing at 12-inch intervals down the length of the edge. Snap a chalk line through all of the marks to create a cutting line.

    Place a board or scrap of plywood underneath the rolled-back edge to protect the carpet below from the knife blade. Lay a straightedge along the chalk line, and cut through the carpet with a carpet knife or utility knife, using the straightedge as a guide for the knife. Be sure to cut down a single line of backing threads as you work. A very uniform, straight cutting line is essential to make the seam as invisible as possible.

    Person cutting carpet lines
    Courtesy of TrendTreasures Inc.
  3. Cut the Second Edge

    Lay the newly cut edge of carpet back down over the uncut piece. It should still overlap the bottom piece by about 2 inches.

    Place a straightedge along ​the edge of the cut carpet, and use the knife to cut through the bottom piece of carpet, slicing through only a single row of threads, as before. Again, take care to make the cut as straight as possible.

    Pieces of cut carpet
    Courtesy of TrendTreasures Inc.
  4. Position the Seaming Tape

    Center a line of carpet seaming tape underneath the two cut edges of the two pieces of carpet, with the adhesive side facing up. Lay out the tape along the entire length, with the two pieces of carpet perfectly matched along their edges. Using a single piece of tape for the entire seam helps to keep the seam tight. Carefully butt the two edges of the carpet together as tightly as possible.

    Person Laying Carpet Tape
    Courtesy of TrendTreasures Inc.
  5. Position the Seaming Iron

    Place a carpet seaming iron under the two pieces of carpet, against the carpet seam tape, and plug in the iron. Depending on the type of tape you use, you might need to heat it for several minutes to begin activating the adhesive on the seam tape. Follow the tape and iron manufacturer's recommendations for heating times. 

    Person laying with tape heating iron.
    Courtesy of TrendTreasures Inc.
  6. Join the Seams

    Move the iron slowly and steadily down the seam and across the tape, allowing it to linger just long enough to activate the adhesive at each point. As you move the iron, press the carpet pieces behind it gently down into the tape while pushing the pieces tightly together.

    As you move down the seam with the iron, roll over the joined seam behind the iron, using a seam roller to press the carpet edges into the tape adhesive and ensure they lie flat. 

    After rolling, place heavy objects such, as large books, over the rolled area of the seam to hold the carpet in place. Leave the weights in place until the adhesive sets.

    Person laying carpet with tape heating iron.
    Courtesy of TrendTreasures Inc.
  7. Complete the Seam

    Continue seaming the carpet until you reach the end of the seam. Leave the weights on the seam for another 15 minutes before removing them. The final result should be a carpet surface that appears nearly unbroken, with the pile threads hiding the seam.

    A Carpet Seam
    Courtesy of TrendTreasures Inc.