Photograph of  grass growing indoors in this unusual home Best Practices Guide Selecting & Installing Indoor Carpeting & Carpet Padding

  • CARPETING, SELECTION & INSTALLATION - CONTENTS: Indoor wall-to-wall carpeting types & choices. Recommendations for types of carpet padding. Interior carpeting installation best-practices to avoid wrinkles, bulges, showing seams. Plastic laminate flooring choices, installation guide. Sound & noise control, principles & methods. Where to buy products for building interiors: manufacturers, industry associations
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Carpet & carpet padding selection & installation best practices guide.

This article series discusses and provides a best construction practices guide to the selection and installation of building interior surface materials, carpeting, doors, drywall, trim, flooring, lighting, plaster, materials, finishes, and sound control materials.

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Guide to Selecting Indoor Wall-to-Wall Carpeting: Materials, Grades & Carpeting Installation Best Practices

Materials Used in Wall to Wall Carpeting

Figure 5-17: (C) J Wiley, S Bliss

As explained in the book, Best Practices Guide to Residential Construction Chapter 5, Interior Finish:

Over 90% of the carpet installed in the United States is tufted, meaning that loops of yarn are stitched through a fabric backing, usually polypropylene, and glued in place with styrene-butadiene (SB) latex adhesive.

This carpet is backed by a thick layer of SB latex or, in higher-end products, a secondary layer of fabric.

[Click to enlarge any InspectApedia image or table]

The loops of yarn are either left in place for loop-style carpets, such as Berbers, or cut with blades for cut-pile carpet (Figure 5-17).

Traditional woven carpeting, representing only about 2% of U.S. production, is costly but creates a dimensionally stable and durable carpet including velvet, Axminster, and Wilton.

With modern manufacturing techniques, however, nearly any style can be created using tufted construction. Common styles and their wear characteristics are shown in Table 5-8 given below.

Table 5-8: (C) J Wiley, S Bliss

Nylon, considered the most durable synthetic carpet, accounts for about 60% of all pile carpeting. Most of the remaining are made of olefin and polyester, with wool accounting for less than 2% due to its high cost. Nylon is popular because of its good resilience (springs back rather than crushing) and overall durability (Table 5-9).

Additives can give nylon good stain resistance.

Table 5-9: Carpet Fiber Types (C) J Wiley, S Bliss

Because olefin (polypropylene) is prone to crushing, it is generally used for low-pile designs, such as Berbers. Olefin is also widely used for indoor/outdoor carpeting used in high-moisture and recreational environments because of its resistance to moisture, mildew, and stains. Polyester carpeting is very soft to the touch but not as durable as the other synthetics.

Quality Factors in Evaluating Wall to Wall Carpeting

Other than the material, the durability of a carpet depends on several factors: density of the tufts, twist of the yarn, and heat setting.

Density of Wall to Wall Carpeting Pile

Density refers to how much yarn is used in the pile. The more tufts of yarn per square inch, the more yarn there is to wear and provide a resilient surface that resists crushing. The denser a carpet, the harder it is to push through the carpet to the backing with your fingers.

Also, when bent back in a U-shape with the pile facing outward, a denser carpet will show less of the backing. Density is measured in stitches per inch or face weight, which is the weight of the fiber in the pile per square yard of carpet. When divided by the pile height, this gives the average density per inch of pile. These numbers are useful for comparing similar products that use the same materials, but otherwise can be misleading.

Yarn Twisting Effect on the Durability of Wall to Wall Carpeting

Twisting the yarn enhances the durability, particularly in cut-pile carpets. In most nylon, olefin, and polyester cut piles, the twist is set by heat or steam to help the carpet retain the twist. The cut ends of the carpet pile should be neat and tight.

Pile Height of Wall to Wall Carpets

Higher piles create a softer feel and more luxurious appearance but tend to crush more easily and are more difficult to clean.

Color and Pattern of Wall to Wall Carpets

Most carpeting today is very colorfast. Solution-dyed carpet, in which the dye is added to the fibers when they are made, is extremely colorfast. Yarndyed carpet, which is dyed after the yarn is made, provides some color variation and is also very colorfast. In general, light-colored carpets show dirt and stains, while dark colors show lint.

Mottled colors such as tweeds and textured patterns tend to disguise dirt and wear, and are good choices for high-traffic areas and rooms where spills or stains are likely.

Guide to Wall to Wall Carpet Durability Ratings and Warranties

Many manufacturers rate the durability of their carpeting on a numeric scale or with descriptions such as low, medium, and high durability. These are a useful gauge of performance, but the proof is in the warranty. Look for a 7- to 10-year wear-and-stain warranty. Find out if the warranty is prorated or covers the full replacement cost. Also, read the fine print, as certain kinds of stains, such as pet stains, are often excluded.

Carpet Pad Selection & Installation Guide

Carpet adhesive and padding (C) Daniel FriedmanBy absorbing much of the impact of foot traffic, carpet padding helps prevent the carpet fibers from getting crushed and wearing out prematurely. The cushioning effect also makes the carpet more comfortable underfoot.

Good padding is sufficiently firm and resilient to absorb foot traffic, and durable enough that it will not break down or collapse over time.

Good padding also increases insulation and soundproofing and makes carpeting easier to vacuum by allowing air to circulate through the carpet.

For residential applications, pads should generally be no more than 7/16 inch thick for high piles and no more than 3/8 inch thick for Berbers or low piles.

In general, softer, thicker pads are used in bedrooms, dens, and other rooms with light traffic. Thinner, firmer pads are recommended for living rooms, family rooms, hallways, stairs, and other high traffic areas. Berber-style carpets also require thinner, firmer cushions for support.

If too thick, the pad can cause too much flexing in the carpet, weakening the backing and opening seams. A carpet pad that collapses, or starts out too thin, can cause carpeting to wrinkle or wear out quickly. Seams in the pad should run perpendicular to the carpet seams or be offset by at least 6 inches.

Foam Padding Used Below Carpets

Prime urethane pads are the least expensive, but have a tendency to compress with use, particularly in high-traffic areas. As the pad compresses, the carpet backing can break down from too much flexing. For that reason, prime urethane pads are not recommended for carpeting subject to moderate or heavy traffic. One exception is a proprietary urethane called Omalon (E. R. Carpenter Co.), which has a special cell structure that resists crushing and is guaranteed for the life of the carpet.

Rebond Padding Used Below Carpets

Bonded or re bonded pads, made of multicolored scraps of high-density polyurethane foam bonded together, are the most common in residential construction.

The denser the foam, the better the feel underfoot and the durability. The Carpet and Rug Institute (CRI) recommends that rebond be a minimum of 5 pounds per cubic foot and 3/8 inch thick for light-traffic areas, such as a bedroom, and 6.5 pounds and 3/8 inch thick for heavy-traffic areas, such as hallways. For longer wear in high-traffic areas, use a 7- to 8-pound rebound. For a more plush feeling, choose a7/16-inch thickness.

Fiber Padding Used Below Carpets

Natural and synthetic fiber pads are sometimes used under area rugs, commercial carpets, and some Berber carpets. They are made of jute or recycled synthetic carpet fiber and are among the densest and most resilient pads. Synthetic fiber pads are the best choice for potentially damp concrete floors. With synthetic fiber pads, look for a minimum density of 7.5 pounds per cubic foot or 12 pounds for jute. The thickness should range from 3/8 to 7/16- inch.

Special Padding Used Below Carpets

Some Berber carpets require special padding. In general, the bigger the loop in the Berber, the firmer the padding should be. Woven carpet may also require special padding, typically an extra-dense fiber pad or, in some cases, a heavy frothed foam.

Installation Procedure for Carpeting

Stretch-in installations using tack strips along the room perimeter are the most common approach in residential carpeting. Glue-down installations are primarily used in commercial work but are used residentially over slab-on-grade and in basements.

Glue-down installations can either use carpeting with an attached cushion backing or the “double-glue” method in which the pad is glued to both the concrete and the carpet. For installations over concrete, the concrete should be fully cured and surface free of dirt, dust, and any curing agents.

Subfloor Requirements for Carpeted Floors

A good carpet installation starts with a properly prepared subfloor. The minimum recommended subfloor is 3/4 inch T&G plywood, nailed and glued. For a higher quality job, an 1/4-to 3/8-inch underlayment should be installed over the plywood with the seams offset from the subfloor.

Follow the underlayment specifications for resilient flooring, discussed above. Check for loose or squeaky spots and nail with spiral or ring-shank nails before installing the carpet.

For a level transition, the top of the underlayment should sit about 1/2 inch below the finished height of adjacent solid flooring materials, such as wood, tile, or resilient flooring.

Carpet and pad can also go over hardwood floors or tightly glued resilient flooring. Repair any loose areas or damage in the existing flooring before installing the pad and carpet.

How to Handle Seams in Wall to Wall Carpeting

Most residential carpeting in the United States is available in either 12- or 15-foot-wide rolls, but the installer needs a few inches of waste on each end for stretching installations, limiting the size of a room that can be done with no seams.

Since all seams are visible to some extent, they should be placed where they are the least visible and get limited traffic, such as inside of closets. Seams should always run with the pile in the same direction.

Where a room is lighted from windows, the seams should go perpendicular to the windows. In hallways, place any seams along the length of the hall. If a seam must be between rooms, make sure it is hidden when the door is closed. As the fibers are compressed from wear over time, seams become more conspicuous.

Seams are easiest to conceal in deep, dense, cut-pile carpeting.With short loop-pile carpets, such as Berbers and other loop-pile carpets with heavy textures and irregular rows of tufts, it can be difficult to hide seams. Also carpets with pads hide seams better than glue-down installations.

Where seaming problems are anticipated, use wider 6-inch hot-melt tape at seams rather than the standard 3-inch tape. The wider tape helps avoid a high spot at the seam.

Carpet Installation: How Warm-Up and Stretching During Installation Avoids Wrinkles

To avoid problems with wrinkling, carpeting should be warmed up to the normal room temperature for about 24 hours before it is installed. This can take place in the home or in a heated warehouse. The building should also be heated to normal temperatures before and during the installation and be free of excess moisture. If the carpet is installed cold, it can expand and wrinkle when heated to normal conditions.

Wrinkling and ridging at seams can also result from carpeting that is not adequately stretched during installation.

While manual stretching was adequate for older carpeting with natural jute backing, the polypropylene backing used today requires the greater force of power stretching. In fact, many manufacturers will not warrant their carpet on rooms larger than 12x12 feet unless it is power stretched.

The stretched carpet is held in place with tack strips nailed around the perimeter of the room about  1 2 inch in from the baseboard. Standard 1-inch-wide tack strips are adequate for most carpeting, but some heavy woven and Berber-style carpets require 2-inch strips (or two 1-inch strips) to hold them securely in place.

Health Effects of Indoor Carpeting

In recent years, a number of homeowners and advocacy groups have attributed a variety of health problems to exposure to new carpeting. Although studies have been inconclusive, the carpeting industry has taken steps to reduce exposures of certain chemicals and has established a certification program for low-emitting carpets. For more information, see CARPETING & INDOOR AIR QUALITY).

-- Adapted with permission from Best Practices Guide to Residential Construction.

Resources: Manufacturers, Industry Associations, & Sources of Carpeting & Carpet

-- Adapted with permission from Best Practices Guide to Residential Construction.

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