By Dave Holbrook

Carpeting is one of the last items to be installed in a new home or remodel and an indication that the job's winding down. In all likelihood, you've hired the installation out, so you don't have to worry about the how-tos, or force yourself to slow down and do things right. Contractors have bigger fish to fry. But if you haven't set the job up correctly, prior to the installer's visit, carpeting can spell trouble. If you don't like paying for mistakes, there are a number of preparatory steps to cover before they're, well, covered for good. Common customer complaints include visible or ridging carpet seams, unfastened edges, shading irregularities, shedding, pulled fibers, wrinkling, scuffed baseboards, squeaking floors, and telegraphing floor irregularities. Some of these problems can be laid at the installer's feet — but not all of them. The more you do to set the job up properly, the better the outcome is likely to be.

Installation Prep

It's a good idea to preview existing conditions with the installer and make a record of any damage to paint, walls, and other finishes before carpet installation begins. The floor in any rooms receiving new carpeting should be vacuum-clean. If you're replacing old carpeting, vacuum it first, before removal, to reduce the release of airborne contaminants (see "Carpet Emissions," below). While other flooring types might require removal or a layer of new underlayment, cushion and carpet can usually be run directly over existing wood, ceramic or composition tile, concrete slabs, or a new plywood subfloor. The condition of the subfloor is important, however; an uneven surface will show right through the carpet. Remove loose materials and fill surface defects such as chipped tiles or gapped flooring with a leveling compound or other secure replacement material.

Most people have heard allegations of allergic reactions to carpet off-gassing, or emissions. If these were substantiated, the problem would be huge; the annual residential market alone accounts for 12 billion square feet of carpet, or around 75% of the installed volume. The Carpet and Rug Institute (CRI) states that "off-gassing" is a misnomer and argues that carpet is one of the lowest emitters of volatile organic compounds (VOCs) in the indoor environment. This position is essentially supported by the U.S. Environmental Protection Agency. Carpet is made of the same natural and synthetic materials found in clothing and other everyday fabrics. Formaldehyde is not used in the carpet manufacturing process in the U.S. It may occasionally be detected in old carpeting, having been absorbed from other sources within the indoor environment. According to CRI research, new carpet's emissions will dissipate to an undetectable level within 48 to 72 hours. To minimize complaints, CRI counsels installers to observe the following guidelines: • Vacuum the old carpet before removal to minimize the amount of dust particles. • Vacuum the floor immediately after the old carpet and cushion have been removed. • Open windows and doors, if possible, for an adequate supply of fresh air. Consider using window fans, exhaust fans, room air-conditioning units, or other means for fresh air ventilation during the removal of old carpet and the installation of the new carpet. • Continue operating the ventilation system at normal room temperature for 48 to 72 hours after installation. If possible, leave doors and windows open to increase the flow of fresh air. • If the carpet is to be glued to the floor, use a low-emitting floor covering adhesive displaying the CRI Indoor Air Quality Adhesive Testing Program label that identifies tested, low-emitting products. • If any occupants consider themselves to be unusually sensitive, they may wish to avoid the area or leave the premises while the old carpet is being removed and the new carpet installed. • If possible, unroll the new carpet in a well-ventilated area for a day or so before installation. When it's kept clean, carpeting acts like a big filter, preventing dust and dirt from becoming airborne. Vacuuming the carpet should be a weekly chore and is not a job for a wimpy vacuum cleaner. A powerful vacuum, preferably one with a rotating beater brush, is a carpet's best friend. The CRI independently and randomly obtains and tests vacuum cleaners' ability to satisfactorily remove and contain a predetermined amount of dirt from a standard test carpet in four passes. Vacuum cleaners that pass this test receive the CRI's IAQ (indoor air quality) label. Your clients can check their machine's credentials via the CRI's consumer number or website. Incidentally, despite the availability of DIY extraction-type carpet shampooers, carpet should be shampooed (preferably by a professional using professional equipment) only every 12 to 24 months. Repeated wetting can break down the acrylic bonding agent and dramatically shorten the carpet's service life. —D.H.

Although glue-down carpeting is less common in residential applications, basement and porch installations are often glued. Commercial carpet tile is always glued. Make sure concrete slabs have been cured and are clean, dry, and free of dust and any curing agents that might interfere with an adhesive bond. A small amount of moisture (maximum 3 pounds per 1,000 square feet per 24 hours) wicking through the concrete is permissible, but excess moisture will interfere with a proper adhesive bond. Stretch-in carpet should always be power-stretched, using a telescoping mechanical stretching tool braced against a "power wall" — any partition that will provide resistance in the opposite direction of the stretch. Sometimes installers find that interior partitions have only been tacked in place and give way during stretching. It's a little late and a little embarrassing to have to secure walls when you're at the carpet stage, so make sure the bottom plates are properly nailed off before drywall. Threshold transitions call for consideration. Installers try to avoid seaming across a door opening because foot traffic tends to highlight a seam. If the carpet will be of another color or pattern at this juncture, it may not be an issue; otherwise, a wood threshold provides a nice-looking transition. Door clearance can be a problem, especially in remodel situations. Depending on carpet thickness, you may need as much as an inch or more clearance above the subfloor. Mark the doors in place for trimming as necessary, and remove them before carpet installation. Bifold-door hardware usually requires a floor mounting block at the hinge jambs. It's best to install these before carpeting — the installer can easily fit the carpet around the blocks.

Terminating the carpet at a finished wood ground tends to look neater than an elaborate wrap at the base of a balustrade or stair railing (see Figure 1). Carpet installation is also simplified by this approach, saving labor.

Figure 1. Finished wood thresholds and grounds at balustrades and stair railings provide a neat transition and involve less carpet installation labor. Plan on Seams

If your clients haven't already participated in the selection and planning process, make sure they understand that seams show and have them approve the seam locations. Manufacturers plainly state that there are no invisible seams. As part of the measuring process, the installer typically draws a detailed installation plan that shows area dimensions and proposed seams. The carpeting supplier relies on this plan to precut rolls to the appropriate lengths. To make them less obvious, seams should run perpendicular to windows that let in a lot of sunlight. Your customers should also understand that the degree to which a seam is visible depends on carpet style and quality. Heavily textured loop tufting often doesn't align in strict, straight rows. If the seam cut bisects a tuft, loose strands will pull free and highlight the seam. If the seam cut is forced to follow an irregular tuft row, exact alignment with the secondary carpet section will be impossible and the seam will be more pronounced. Seams can be particularly difficult to conceal in berber carpet, a popular style with a pronounced texture and informal appearance. The least visible seams are typically in dense-pile, cut-loop, plush carpeting (Figure 2).

Figure 2. The visibility of a carpet seam depends on many factors, including the type and regularity of the face tufting. Irregular tufting rows force seam cuts to wander, making a true edge match impossible. Textured, berber styles are notoriously difficult to seam. Measuring for carpet. Professional installers take pattern repeats, seam placement, room irregularities, closets, and stairways into account when measuring. To come up with a rough quantity for an allowance or estimate, multiply the room's length by its width, and add about 10% to account for jogs and pattern matching. Carpeting is available in 12-foot- and 15-foot-wide rolls. Keep in mind that seams should always be made edge to edge or end to end. A right-angle turn in the run of the roll will cause the twist in the face yarn to catch the light differently and appear as an improper color match.

Cushion First

It's nearly impossible to wear out a carpet's synthetic face fibers. Carpet is often replaced, not because it's worn out, but because the pile has become crushed and ugly. Although carpeting can be installed directly over a bare floor, industry studies suggest that the appropriate cushion can greatly extend its useful life. Carpet cushion absorbs most of the impact from traffic, preventing distortion of the carpet's surface. Equally important to the consumer, cushioning adds a luxurious "feel" and give to the carpet. Carpet manufacturers provide specific cushion recommendations for the various styles of carpet made. For residential use, cushion applications are divided into two service classes. Class I includes light- and moderate-traffic areas, such as living rooms, dining rooms, and bedrooms. Class II covers high-traffic areas like entries, hallways and corridors, and all stairways. You should always install the appropriate cushion for the type of service expected. Regardless of carpet type, the cushion should never be thicker than 7/16 inch; a thicker cushion may "bounce" the carpet backing free from the tack row. Generally, a low-nap or loop carpet should be installed over a 3/8-inch-thick cushion, with the marginally thicker 7/16-inch cushion reserved for plush and deep-pile carpets. Keep the less ambulatory population in mind, too: Walking and wheelchair use are both impeded by a too-thick cushion. Cushion seams should be installed at right angles to carpet seam direction. Where this isn't possible, cushion and carpet seams should be offset by a minimum of six inches. Cushion types. Urethane foam is probably the most commonly used carpet cushion in residential installations and is defined in pounds per cubic foot of density, typically ranging from 4 to 12 ppf (Figure 3).

Rebonded urethane foam cushion, made from recycled foam seconds, is rated in pounds per cubic foot of density. The denser the foam, the better the "feel" and durability underfoot.

Four-pound rebond cushion is an entry-level, fast-and-dirty cushion and should not be considered for a quality residential installation. Eight-pound rebond is the best cushion to use in common traffic areas under plush styles and some berbers. This cushion is softer than felt but firmer than six-pound rebond, which, when installed under plush styles, enhances their soft feel. Rubberized jute or synthetic felt, made from new carpet waste fiber, is often installed under berber and commercial styles, and gives a firm feel underfoot (Figure 4).

Figure 4. Synthetic felt cushion, made from recycled carpet textile fibers, gives a firm feel underfoot and is typically applied under berber and dense, low-nap, or commercial-style carpeting. Because of its better "breathability," it's a good choice for potentially damp concrete basement floors.

Jute and felt are also good choices for basement slab installations, where moisture may be a concern, because an open fiber mat allows moisture to pass through more readily than a foam cushion.