Exterior Products Review: Self-Adhered Roof UnderlaymentsPeel and Stick: Self-adhered underlayments are helping to protect all types of roofs.

  • By Stephanie Herzfeld
  • Source: BUILDING PRODUCTS Magazine
  • Publication date: 2004-09-27

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 underlay-ments 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.

Entrapment

According to Reinhard Schneider of G-P Roofing Products, having trapped water in roofing is a given, whether it seeps in through miniscule penetrations, condensation, or some other method.

Manufacturers and roofers recommend that you apply the proper combination of materials to help keep water out and to withstand harsh weather. And roofer John Alajoki stresses the importance of proper attic ventilation. “If you're depending on felt to let the roof breathe, it's ineffective,” he says.

Mission Viejo, Calif.-based Alajoki says he asks his clients to sign a contract requiring that the house have sufficient attic ventilation before he begins work on the roof. If they refuse, he has the clients sign a waiver so he's not accountable for any future damage.

“Proper attic ventilation just is part of a healthy roof,” he states.—S.H.


GP Gypsum

GP Gypsum

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, stabilizes, and protects against delamination, deterioration, warping, and other damage to roof decks, claims the maker. 800-225-6119. www.gp.com/gypsum.

Protecto Wrap

Protecto Wrap

Protecto Wrap. Rainproof peel-and-stick roofing underlayment is a rubberized asphalt sheet that is reinforced with a non-woven polyester fabric. Specifically made for low-pitched roofs, the waterproofing product has a white reflective coating for added safety, heat reduction, and short-term UV protection, says the maker. 800-759-9727. www.protectowrap.com.

Classic Products

Classic Products

Classic Products. RoofTopGuard II is a five-layer polypropylene and polyethylene roofing underlayment that is distributed in the western United States. It is impervious to insects, vermin, rot, and fungus and meets numerous strength, water-tightness, and water-vapor transmission codes to provide benefits for any roofing system, says the manufacturer. 800-543-8938. www.classicroof.com.

Grace Construction Products

Grace Construction Products

Grace Construction Products. Ice & Water Shield, a self-adhered roofing underlayment, sits between the shingles and the roof deck to protect against leaks. Made from rubberized asphalt adhesive that's backed by a polyethylene layer, the product seals around nails and won't crack, dry, or rot, says the maker. It can be applied to all standard roof coverings. 866-333-3726. www.graceconstruction.com.

Certain Teed

Certain Teed

CertainTeed. Flintlastic and GMS roofing under-layments are available in eight of the firm's most popular Landmark shingle colors. The roofing membranes can be installed over a variety of substrates on low- and medium-sloped roof decks; GMS is intended for hot asphalt or cold-process adhesive applications. 800-233-8990. www.certainteed.com.

Elk

Elk

Elk. Made with the firm's UltraMat fiberglass mat, All-Climate self-adhering roofing underlayment and waterproofing membrane features a split release backing that allows for wrinkle-free installation on all types of roofs, asserts the maker. VersaShield fiberglass underlayment is available for metal roofing systems. 972-851-0400. www.elkcorp.com.

Benjamin Obdyke

Benjamin Obdyke

Benjamin Obdyke. Cedar Breather underlayment for wood shingle and shake roofs provides space for continuous airflow between the solid roof deck and the shingles, the maker says. Its nylon-matrix design allows the shingle's underside to dry, eliminating excess moisture, preventing thermal cupping and warping, and reducing potential rotting, claims the maker. 800-346-7655. www.benjaminobdyke.com.