By Nigel F. Maynard. In home building, it's easy to ignore the things buyers cannot see for the things they can. This approach often leads to problems. Take underlayment, for example. Homeowners never see it, but a quality product will result in stiff, level floors. An inferior product can create swelling or turn the floor into a trampoline.

Doug Melien, marketing manager for the Multiply Plywood underlayment business at Portland, Ore.-based Columbia Forest Products, says most builders do use quality products, but many are simply interested in the lowest installed cost.

"One of the most common failures we see is 'seam see-through,'" Melien says. "What happens is that the floor undergoes a change caused by moisture, and it pushes up the vinyl." An inadequate underlayment can also cause bounce, deflection, and vibration with ceramic tile floors, he adds.

To combat this, builders should first consider what type of flooring will be installed in the home, since some underlayment products are suited for different types of floor. Melien says 1/4-inch-thick, 4-by-4-foot hardwood underlayment is one of the best products to use under resilient floors such as vinyl, rubber, and cork. Its measurements give dimensional stability, and hardwood provides a smooth, even floor. The manufacturer also offers a 3/8-inch-thick product.

Many homeowners "don't understand the importance of their floor underlayment," says Billy Houston, vice president of sales for the structural panels division of Atlanta-based Georgia Pacific. "But we've found that most homeowners who have experienced squeaks and bouncy floors don't want to live with them in their new home."

Houston says the company's ToughPly Sturd-I-Floor meets consumer demand for a quiet, stiff, and durable high-performance flooring system. Previously, many flooring materials required a separate underlayment grade of plywood over the subfloor, Houston explains. But Sturd-I-Floor, he says, is a combined subfloor-underlayment product designed for single-layer floor construction.

For more product information, search Hanley-Wood's ebuild catalog.

Courtesy Natural Cork

Cork it: This cork underlayment is ideal for sound control and can be installed under any type of floor covering, says the manufacturer. A rot- and moisture-resistant product, cork also reduces and absorbs the moisture created by condensation and is naturally resistant to mold, mildew, and insects. The product is available in sheets and rolls and in various thicknesses. Natural Cork. 706-733-6120.

Courtesy Georgia Pacific

Rough and tough: No need to install a subfloor and an underlayment under ToughPly Sturd-I-Floor, because the single-layer product is almost four times as stiff as ordinary plywood, the manufacturer says. The product's stiffer properties mean that builders can increase floor joists from 16 inches on center to 19.2 or 24 inches. Measuring 7/8 inches thick, the plywood panels also will result in quieter floors, the company says. Georgia Pacific. 800-284-5347.

Courtesy Columbia Forest Products

Hard wood: Multiply Plywood is a puncture-resistant hardwood panel that provides a smooth and durable foundation over new or existing subfloors, according to its manufacturer. It won't stain or discolor vinyl flooring, and each panel has a nailing pattern for accurate installation. Measuring 4 feet by 4 feet, the product offers dimensional stability and is available in 1/4-inch thickness for vinyl and 3/8-inch for ceramic tile. Columbia Forest Products. 807-887-0458.

Courtesy Weyerhaeuser

High fiber: FiberFlor's uniform thickness minimizes irregularities in subfloors and improves the dimensional stability of the entire floor system, says the manufacturer. It can also be used under many types of flooring, including carpet and laminate. The surface is hard, so it will resist splitting from fasteners, and it has a nail grid for accurate installation. Weyerhaeuser. 877-235-6873.