Peel and stick: self-adhered underlayments are helping to protect all types of roofs

Building Products, Sept-Oct, 2004 by Stephanie Hersfeld

Harsh winter weather used to send shivers down the spine of many contractors, causing some of them to worry about how their clients' roofs were holding up. These days, builders, remodelers, and roofers are fretting less because they are embracing peel-and-stick waterproofing underlayments that help protect all kinds of roofing materials.

The application of self-adhesive underlayments is expanding for a number of reasons, says Reinhard Schneider, technical development manager for Georgia-Pacific Roofing Products. Self-stick products cause less harm to the roof deck than regular underlayments because they're less susceptible to corrosion. In addition, they aren't installed with nails or screws so they don't weaken the deck or transfer heat to the interior that can make the air conditioning system less efficient. And there are no holes that could allow moisture to seep in.

EASY INSTALLATION

Like all types of underlayments, peel-and-stick products are installed between the roof deck and the roof covering. Made for all types of roofing materials, they're designed to help the roof shed water and provide secondary weather protection for the entire surface area.

Their greatest benefit to builders, however, is that they get a house covered quickly, allowing work to start on the interior before the entire roof is nailed down, says John Madden of James Myers, a Beltsville, Md.-based roofing installation company.

Originally intended for full-roof applications in areas where ice damming is a concern, self-stick underlayments are used for partial roof coverage in less severe climates.

However, they can be applied in full-roof applications in milder climates if the design warrants it, notes Tom Bollnow, senior technical director of the Rosemont, Ill.-based National Roofing Contractors Association (NRCA). For instance, they can be used over a low-slope roof because that type of design is more susceptible to water accumulation than other types, he says.

DYNAMIC DUO

Special circumstances aside, peel-and-stick products often are used in conjunction with traditional roofing felts (which are nailed in across the entire roof deck), on the edges, eaves, and valleys of roofs. But if self-stick products are spread over a roof that isn't designed for them, the self-adhering laps can seal together causing the roof to suffocate, Bollnow cautions. Moisture problems could occur because water gets trapped.

Installing self-adhesive options with traditional underlayments is less expensive than using strictly self-adhesive materials. Although roofing underlayment costs only account for about 10 percent to 15 percent of the overall roofing budget, peel-and-stick products may be three to five times more expensive than felts, pros estimate.

Meanwhile, fiberglass materials are starting to compete with organic felts for market share because they weather better than typical organic 15- and 30-pound coverings. Also, pulp and paper-based products can wrinkle and expand and contract, and even telegraph (show through shingles) when they're exposed to the elements, says Bollnow.

Nevertheless, it's important to use felts as part of an entire underlayment system because many local building codes have exacting specifications that require pros to protect the roof deck against snow, rain, foot traffic (during construction), and more, claim industry experts.

"Contractors use it to primarily cover the roof until they can shingle in new construction and for added protection in re-roofing," comments Marcia G. Hannah, chair of the Asphalt Roofing Manufacturers Association (ARMA) communications committee and vice president of marketing for the CertainTeed roofing products group.

John Alajoki, owner of J.A. Roofing in Mission Viejo, Calif., says he lays felt out first, but puts down fresh underlayment if he thinks the felt has been exposed too long before shingle installation begins.

MATCH MADE

Although you can mix underlayments and shingles, association and manufacturer officials recommend sticking with one brand of roofing products because they complement each other.

"You get better wind resistance and a better overall system because all the components are designed to work together. Plus you get [longer and more comprehensive] warranties," says Mike McLintock, Elk's director of marketing. Elk, for example, offers UltraMat underlayment along with roofing shingles.

Down the road, pros predict that there will be a proliferation of more durable synthetic products, although contractors' acceptance of these items may be slow.

"I don't like to use my customers as guinea pigs; I like to use tried-and-true, established products," Alajoki says.

GP Gypsum. DensDeck DuraGuard roof board provides a tough, peel-and-stick substrate for all types of roofing systems. It features a moisture-resistant gypsum core and fiberglass mats on both sides for extra strength and durability, says the maker. DensDeck DuraGuard stiffens, stabilizer, and protects against delamination, deterioration, warping, and other damage to roof decks, claims the maker. 800-225-6119. www.gp.com/gypsum. Circle 290.