How to Seam Carpet and Why Carpet Seaming is Important

carpet seam sealing | Glenn Revere

Installing carpet correctly is not an easy job. There is more to it than “fuzzy side up”! An installer can spend years learning about the finer points of his (or her) craft. One key point that is frequently skipped completely is carpet seaming. “What is that?” you might ask.

Carpet is a fabric that is cut off a long roll and then cut again as needed to fit a room or rooms. Unless the rooms are slightly smaller than width of the carpet, the pieces must be seamed (joined) together into larger pieces to fit the rooms to be carpeted.

When two pieces of fabric — whether cloth for a blouse or carpet for a room — are joined together, the join is called a seam. Most cloth can simply be sewn together into a finished garment. However, the cut edges of carpet are inherently weak where they are joined. These cut edges must be strengthened before they are permanently seamed together. Sealing the cut edges — sealing the seams — gives strength to carpet seams.

Both tufted carpet and woven carpet must have the cut edges sealed before they are joined into seams. The installer has several sealing options, depending on the type of installation, as well as the type of carpet. Most residential installations involve tufted carpet over a cushion, so I’ll explain seam sealing in this regard.

Tufted carpet, basically, is made by tufting (stitching) yarns into a thin fabric sheet. This sheet is called the primary backing. Then a second thin sheet of fabric, called the secondary backing, is glued to the primary backing. An entire roll of carpet could be 150 feet long and 12 feet wide.

Let’s say that you want to carpet your great room and it is 20 feet wide and 25 feet long. That means you need to make a 12 foot wide carpet fit a 20 foot wide room. I won’t get into room layout and exact seam location now. But you can see that you’ll need to cut the carpet roll, fit pieces into this room, and have seams somewhere in the room.

The cut edges that will form the seams will need to be sealed to prevent edge ravel and possible delamination (backing separation). Even though all the industry standards and most carpet warranties specifically include seam sealing, many installers skip this step. Why? It takes extra time and installers as a group don’t make that much money. This is simply a way to cut corners (no pun intended!).

Seams are sealed using one of two methods. With the first way, the installer squeezes a bottle filled with liquid latex rubber. A special tip allows application of a thin bead of latex between the primary and secondary backings. Care must be taken so that the latex only goes between the backings and does not get on the carpet yarns. An experienced installer does this quickly and cleanly. The latex is allowed a few minutes to dry and the carpet is seamed together.

With the second method, the installer uses a specialized seaming iron that directs some of the melted adhesive from the seaming tape under the carpet into the area between the primary and secondary backing, sealing the seam and forming the seam with only one step.

It isn’t very complicated, but sealing seams is very important. Some installers will seam seams for loop pile carpet, but not cut pile carpet. The thinking is that loops will ravel and zipper, but cut pile won’t. The fact is that any cut edges are inherently weak and must be sealed. It is required by the industry. If you have a carpet failure in your home, even if it is not related to unsealed seams, the carpet manufacturer can turn down your claim based on a substandard installation.

Think about it. You’ve spent a lot of time selecting just the right carpet and just the right color for your home. Do you want your carpet improperly installed so that your warranty could be cancelled? Probably not.

So make sure that your purchase order specifically includes seam sealing with the installation. Don’t let them talk you out of it! If your carpet dealer can’t guarantee that ALL seams (both cross seams and side seams) will be sealed according to industry standards, take your money someplace else. In a year or two, you’ll be glad you did.


Who is Glenn Revere?

Glenn Revere has been a carpet expert since 1973. He’s a certified flooring inspector and the author of All About Carpets, the only book written to protect and inform you about your carpet choices, from carpet buying and carpet warranties to carpet care and maintenance. You can find him on Facebook, Google+ and Twitter.


Photo: Glenn Revere

Tags: , , , , , , , , , , , , , , ,