Download PDF version (265.1k) Log In or Register to view the full article as a PDF document.

No-Callback Carpet Installation, continued

Choosing a Carpet

Tufted carpeting, which accounts for 90% of all carpeting produced, is made up of three layers. The tufting, or face yarn, is stitched onto a primary backing, usually woven, of slit-film polypropylene fabric. A secondary backing sheet of woven scrim polypropylene mesh or non-woven polyester is bonded to the primary backing with liquid synthetic acrylic (latex) or occasionally other types of compound adhesives and extenders. (Natural latex is used only on small, washable rugs.) The secondary backing gives the carpet a firm "hand" and the necessary dimensional stability for stretch-attachment to the perimeter tack row. The face yarn, or tufting, may be cut pile, loop pile, or a combination of the two. Carpet fiber is made from any one, or a blend of, six basic materials: the four synthetics — nylon, olefin, polyester, and acrylic — and wool and cotton. Ninety-nine percent of all carpet is made from synthetic fiber, with nylon accounting for 67% of the pie. Nylon is regarded as the most durable fiber and is available in all carpet styles. Olefin has high stain- and fade-resistant characteristics, as well as good moisture resistance. Most often used in commercial carpeting, it's a good choice for kitchens and bathrooms, sunrooms, and damp-prone basements. Polyester has great stain and fade resistance but is a less durable material than nylon and olefin. It's ideal for children's rooms, where frequent spills and challenging stains are likely. Acrylic is most commonly found in small area rugs, such as bath mats. Wool represents less than 1% of all carpeting but has a luxurious feel and good durability. Generally, wool is considerably more expensive than synthetic fibers. Cotton is typically reserved for loose-laid area rugs. Best choices. Carpet quality is determined by fiber type and the density of the weave; the more yarn stitches, or loops, per square inch, the more durable the carpet and the better it will wear (Figure 5). Heavy traffic areas, such as the family room, hallways, and stairs, warrant the best, or densest, carpet the budget will allow. Less dense carpet is a good choice for a bedroom or home office, where traffic is relatively light. Manufacturers make matching lines of carpet in various densities, so that a lower-cost carpet in the bedroom will blend "seamlessly" with the higher-performance carpet in the hallway.

Fiber density is the key to a durable carpet — generally, the more yarn stitches, or loops, per inch, the better the carpet will wear. Less dense material works best in bedrooms, dens, and other low-traffic areas.Walk this way. Carpet can and should be chosen to minimize the appearance of fiber crushing. Carpet fibers in the traffic areas are not usually worn away but become permanently deformed by repeated impact. Short, dense, cut- or loop-pile carpet, often seen in commercial spaces, is best for disguising high-traffic walkways. Berber and sisal-style carpets, with their textured surfaces and tight loops, are particularly effective at concealing walkways and furniture marks, without presenting a "commercial" look in a residential setting. Performance guidelines. Manufacturers employ a performance rating system to direct carpet selection. The system varies from one maker to the next. Usually, it's based on a five-point scale, with 4 or 5 designating carpet that's best for use in high-wear areas (Figure 6). In a ten-point system, 8 to 10 will be the highest performance rating.


Figure 6. Consumer information is listed on the back of most carpet samples, offering application guidelines on a numerical scale, usually from 1 to 5. Higher numbers connote heavier-duty materials.


Stretched carpet is held in place by catching the carpet backing on the sharp, opposing barbs of a perimeter tack row. Normal 1-inch-wide tack row doesn't always hold carpet securely, so some installers are switching to 2-inch-wide tack row, which provides an additional row of barbs to securely snag the backing (Figure 7).


Figure 7. To improve the tack row's grip on the carpet backing, many installers prefer 2-inch-wide strips, which provide an additional row of barbs.

Look for trouble. Before installation, it's a good idea to look for color defects or variation, missing or pulled pile loops, pole damage from forklift handling, crush lines from improper storage, and any other abnormalities. To avoid permanent creasing, carpet should be stored in rolls; it should never be folded, other than brief buckling to move it into the installation site. Cold call. The vast majority of callbacks on carpet installation jobs are due to puckered or wrinkled carpeting. Although easily corrected, it's also easily avoided with proper preparation and installation. The room in which the carpet is installed should be maintained at a temperature no lower than 65¼F to 70¼F, at least 24 hours prior to installation. Relative humidity should be between 10% and 65%. The carpeting should be unrolled, laid out in the room, and allowed to acclimate for at least 24 hours before it's stretched. Little time is lost to a proper installation; the carpet can be rough-fitted while acclimating, then seamed, stretched, and finished the following day. What you're trying to avoid is stretching a cold carpet in a cold room. When the heat's turned on, the warmed backing will expand and relax, resulting in a loose, wrinkled carpet. Admittedly, this is a tall order on a simple carpet replacement job. Homeowners who have just crammed all their furniture into the bathroom or out on the deck typically want the installer in and out in a day. Acclimating materials isn't on the schedule. However, some suppliers will accommodate this snag by cutting and acclimating the carpet lengths for the job in their heated warehouse, allowing the installer to pick up the rolls just prior to installation. Power-stretching the carpet, rather than using the older technique of "kicking-in," is essential to thoroughly extend and tension the backing material. You should insist that your installer observe this step. In time, most installers find that power-stretching is also crucial to the long-term preservation of their knees, which aren't designed for the impact that kicking-in entails (Figure 8). Not surprisingly, many younger installers admit to skipping the power-stretch step, relying only on the kick-in tool and eternal youth to (inadequately) stretch the carpet.


Figure 8. Although kick-in tools are essential to carpet installation, industry guidelines state that final power-stretching is mandatory to sufficiently stretch the carpet. Installer's knee problems eventually bring them painfully into compliance. Because seam tape doesn't stretch with the carpet, seamed edges should be stretched prior to taping. Seams should also be treated with a liquid seam sealer before taping, to prevent tufts from breaking out of the cut edge. This step is often ignored, but loose and missing tufts loudly signal a seam's presence. Some carpet types — some berbers, for example — are more prone to seam "peaking" than others. Replacing the standard three-inch-wide seam tape with six-inch tape helps prevent peaking. Certain installers ignore this precaution, simply because they don't own a six-inch seaming iron.


More common in commercial installations than residential applications, glued-down carpeting eliminates wrinkling concerns, peaking seams, and the need for a perimeter tack row. Gluing the carpet secures the entire field against displacement under heavy use. The double-stick method, which involves first bonding a carpet cushion to the substrate, then bonding the carpet to the cushion, is the most durable installation. Cushion-backed carpet enjoyed a brief run of popularity, but, apparently, the backing tends to break down irregularly under use, marring the surface appearance. Removing a glued-down carpet isn't particularly difficult, at least after you've gotten an edge started. Occasionally, wood fibers from the top lamination of a plywood underlayment will tear up with the carpet. To control this tendency, and to make disposal easier, it's best to slice the carpet into foot-wide strips before removal. Resist asking your installer to stretch new carpeting directly over an old glue-down job. Industry standards advise against this practice, because the friction of the old carpet pile will inhibit effective stretching. Plus, the old pile will flex underfoot and unevenly stretch the new carpet, creating "bubbles" in the surface.

Carpet and Radiant Floors

Carpet and cushion combined have considerable insulating properties, with R-values up to 2, which may make carpet a marginal choice over a radiant floor. Although inconclusive, certain tests also suggest that when heated, carpet fibers produce chemical emissions. If your clients insist on carpeting their radiant floor, it's a good idea to make sure that the home has a means of supplying a constant fresh air change to avoid possible odor or air-quality complaints. According to a recent article in Radiant Panel Report, a thin, dense rubber pad is best over radiant heat because it's relatively conductive and more resistant to heat degradation. Wool carpeting is 1 1/2 times more insulating than synthetic fiber; the best choice is any thin, synthetic berber or commercial-type carpet. Ironically, radiant heat provides one of the very things carpeting is chosen for, that is, a warm feel underfoot. On a radiant floor, the best carpet is no carpet.

Unavoidable Problems

One 25-year veteran installer jokingly comments that he used to encourage party-goers to drop their cigarettes on the host's carpet for "job security." A spilled glass of red wine can be equally effective. Whatever the source, small burn holes and permanent stains are simple to repair, especially when installation remnants have been retained and stored by the homeowner. The burned or stained area is cut out and a matching carpet patch inlaid and secured with hot-melt seam tape. In a pinch, the installer can "borrow" a patch from a closet or other inconspicuous area and replace it with a compatible or non-matching remnant. Many carpets undergo a stain-resistance treatment at the factory, and manufacturers offer warranties against staining by certain common foodstuffs. Specific exclusions apply, particularly to kitchen and bathroom installations, and to certain stain sources like pets and abuse. Heads up. Carpet suppliers and showrooms often post noteworthy style-specific characteristics and cautions on their sample boards, such as "Difficult to seam" and "Can't be edge bound." It's a good idea to inquire about any peculiarities common to the carpet being selected.

Dave Holbrookis an associate editor at The Journal of Light Construction. Thanks to Ross McDonald of McDonald Installation Systems and Barbara Karras of Cloutier Supply Company, who assisted with this article.

Sources of Supply Carpet & Rug Institute


Carpet Cushion Council


International Certified Floorcovering InstallersAssociation