In the weeks following Hurricane Katrina, Grace Construction Products' residential business director Larry Shapiro says he began to hear from distributors that pros were ordering his company's synthetic underlayments rather than the standard protective blue tarps to cover damaged roofs.

The tarps "just get thrown away afterwards," Shapiro notes. But synthetic underlayments–which he says can remain exposed to sun and rain for up to six months without wrinkling or tearing–allowed workers to start re-roofing jobs with the plan to finish them months later when post-hurricane shingle shortages are expected to have abated.

Created with a mix of polymers rather than asphalt, synthetic underlayments do not absorb water, which causes wrinkling and tearing in standard felt paper, manufacturers say. They are part of a growing number of increasingly durable products, such as fiberglass blends, self-adhering ice-resistant and water-resistant paper, and heavier asphalt felt, that better address pros' individual project needs.

When selecting which type of underlayment to install, Chip Saalfield, project manager for Harbor Roofing in Painesville, Ohio, first examines the task at hand. "You almost have to look at it on a project-by-project basis," Saalfield notes, adding that for commercial or new residential developments, non-asphalt synthetics are worth the added expense because work often can be delayed for up to 90 days, leaving building materials dangerously exposed to the elements.

But for replacement work on a residence, homeowners are often more concerned about the bottom line. With a quick turnaround, Saalfield says it can make sense to rely on less-expensive 30-pound felt, which is made of recycled paper, cardboard, or wood saturated with asphalt.

Years ago, thinner 15-pound felt was the standard applied to most roofs. But as manufacturers and roofers have emphasized durability, 30-pound has become the norm, Saalfield says.

Blending Durability

To further increase durability, some manufacturers have turned to asphalt/fiberglass blends. Since the late 1990s, they've offered felt saturated with both asphalt and fiberglass. The fiberglass lends strength to the paper, says Mike Loughery, CertainTeed's communications manager, and was intended to address pros' concerns about traditional felt being slippery and prone to wrinkling when exposed to moisture.

But a number of companies have gone beyond blends to synthetic underlayments. Although introduced more than a decade ago, synthetic underlayment use in the United States began swelling just in the past five years, Shapiro says.

Manufacturers say synthetics are more wind-resistant, lightweight, and longer lasting than traditional felt paper. Additionally, Elk's VersaShield was developed to be fireproof and is UL Class A and B fire rated, says Mike McLintock, the company's director of marketing.

As an added benefit, VersaShield for metal roofs, which comes in a light-reflective tan color that doesn't radiate heat, is "cooler [on the jobsite] so workers feel cooler," McLintock says.

In the meantime, weather-resistant fully adhered underlayments, which are designed to protect against wind-driven rain and ice damming, have taken the product category to a whole new level, CertainTeed's Loughery says. These non-synthetic ice and water barriers are particularly valuable in northern climes because they help solve some of the ventilation problems that can occur, Saalfield says.

Waterproofing underlayments from Protecto Wrap, for example, consist of rubberized asphalt, which provides elasticity and some memory properties. It's "like a rubber wet suit for whatever the application is," says Alan Wolpa, the company's Northwest regional sales manager.

Nevertheless, specialty and synthetic products are much more expensive than traditional underlayments. For example, CertainTeed's WinterGuard self-adhering product that resists ice damming and wind-driven rain is four times the cost of the firm's Roofers' Select asphalt-fiberglass-blend felt.

In the future, manufacturers and pros predict underlayments will be more durable, more resistant to ultraviolet radiation and sunlight, and more dimensionally stable. That may mean paying more than for traditional felt, but Saalfield thinks pros will find the expense worthwhile.

"There's becoming more and more demand for the higher-end products because people are seeing that the initial outlay can be more than justified over time," he says.


Grace Construction Products. Tri-Flex 30 underlayments are made of spun-bonded polypropylene coated with a layer of UV-stabilized polypropylene on both sides. This technology, designed to withstand wind, water, and low temperatures, can be left exposed to the elements for up to six months, says the manufacturer. 866-333-3726.

Elk. VersaShield is a non-asphalt fiberglass-based underlayment designed to be used with metal roofing systems to provide both moisture protection and UL Class A and B fire ratings, the firm contends. The product, which contains no gypsum board, is designed to be wrinkle-resistant and create cooler working temperatures, says the manufacturer. 800-288-6789.

Tamko. Moisture Guard Plus is a self-adhering modified bitumen underlayment that creates a water-tight barrier by sealing to the deck and around nails to prevent penetration caused by windblown rain or ice damming, the maker claims. The product self-adheres directly to plywood decks and features a split plastic release film. 800-641-4691.

Protecto Wrap. The Rainproof MS roofing underlayment is made of rubberized asphalt with a fiberglass-reinforced membrane. This product is intended for use on eaves, ridges, valleys, dormers, and skylights to protect against wind-driven rain and ice dams. This model is self-sealing and features a granular, skid-resistant surface, says the manufacturer. 800-759-9727.

CertainTeed. Roofers' Select underlayment is laid on top of the roof deck to protect it from moisture prior to shingle installation and from leaks throughout the life of a roof. Additionally, waterproofing underlayments like WinterGuard can be used to protect against ice dams and wind-driven rain in vulnerable areas, such as the eaves or lower edges of the roof, the firm says. 800-782-8777.