Whenever possible, you should install carpet so it doesn’t have seams. It’s not always possible, though, so carpet joints are common in most homes. The trick to joining carpet is to make the seams as invisible as possible. Durable carpet tape helps create the carpet joints. The tape has an adhesive back that you must heat with a special tool, which you can rent. Properly joined carpet seams should stay together for the life of the carpet.
Arrange the two pieces of carpet you are joining so they are side by side in the room. The nap of both pieces of carpet should go in the same direction. Many carpet manufacturers put an arrow on the back of the carpet to help you match the carpet’s nap. Any print or pattern in the carpet’s weave must match along the carpet joints, as well. Place the carpet so you have enough to overlap the two sections 3 or 4 inches. Fold one of the carpet pieces back out of the way.
Load a carpet-seaming knife with a new blade. Unscrew the thumbscrew on the side of the knife that holds the blade, pull out the old blade and insert a new one. Tighten the thumbscrew again. Slide carpet scraps or scrap cardboard underneath the flat piece of carpet to help protect the blade as you use it.
Lay a straightedge tool near the edge of the carpet, aligning it with the nap of the carpet. Set the knife between the rows of carpet nap and run it along the side of the straightedge to cut a straight line. Move the straightedge, as necessary, to cut across the section of carpet.
Remove the blade from the seaming knife and replace it with a new one as before. Pull the carpet scraps or cardboard out from under the carpet you just cut. Slide the edge of the uncut piece of carpet underneath the section you just cut. Align patterns, as necessary, by moving one carpet section forward, back or sideways. When you complete this step, the cut piece should lie on top of the uncut piece in exactly the location where you plan to join them together.
Lay a straightedge along the cut edge of the first section of carpet. As you hold it down, cut the second piece of carpet with a seaming knife. Cut in the groove of the nap as you did the first piece to make it easier to cut.
Preheat the carpet-seaming tool following manufacturer’s directions. Slide carpet-seaming tape with the adhesive side facing up under the edges of the two sections of carpet you cut. Arrange the tape so half its length is under one piece of carpet and the other half is under the other section of carpet.
Slide the carpet-seaming tool between the two cut edges of the carpet with the faceplate of the tool directly on the carpet tape. Let the tool heat the glue on the tape until it melts, then move the tool forward the length of the tool. Heat that section of tape and move it forward again. Behind the tool, press your hand onto the seamed area to seat the carpet into the adhesive. Alternatively, run a rolling pin over the seam to seal it to the tape.
Continue to work your way across the carpet joint. As you finish a 2- or 3-foot section of the seam, set weighted objects along the seam to help seal the glue to the back of the carpet.
Clean glue off the seaming tool’s faceplate with scrap carpeting. Do not allow the tool to cool without cleaning it. Do handle it with care while it’s hot.