They're slippery, they tear, and they're expensive.
That's what some people think about synthetic roofing underlayments. Now, a variety of manufacturers have improved their synthetic offerings to tackle these complaints. Meanwhile, manufacturers have noticed greater use of waterproofing underlayments–barriers designed to keep out ice and water–in more parts of the country, and sometimes on the entire roof.
James Kirby, associate executive director of technical communications with the National Roofing Contractors Association (NRCA), says most people use asphalt-based products to cover their roofs. However, if these products get left uncovered outside, they absorb moisture and wrinkle.
"The trend right now is to use more synthetic-based material that doesn't absorb a lot of water," Kirby says. "They can sit out a bit longer, and the manufacturers, of course, have designed them so they don't break down under UV light [for a specified amount of time]."
Even though synthetic products initially may cost more than roofing felt, they may save builders time and money in the long run if they are building homes that may need to remain without shingles for a while. Additionally, manufacturers claim that synthetic products cover more per roll and are lighter than felt rolls.
That still leaves roofing contractors' other big concern about synthetics: slipperiness.
Ralph Bruno, executive vice president of global sales and marketing for Propex's recently released Opus Roof Blanket, sees the labor-saving benefits of synthetics, combined with recent safety improvements in the products, propelling sales in the underlayment market.
To address safety concerns, the Roof Blanket was ASTM tested in a third-party lab for slip resistance under both wet and dry conditions. It scored higher than other synthetics and felt, Propex says. Additionally, the product can be left exposed to UV rays for up to 30 months, and the company offers a tear-free guarantee.
But the biggest benefit, Bruno says, comes from its labor savings. Because the product is lighter than felt and can cover twice to four times what felt can cover per roll, it installs 30% to 40% faster, Bruno says. It costs a little more than for 30-pound felt, he adds.
Typar also has a new synthetic underlayment that is similarly priced to 30-pound felt. Called Surround SR, the product also was ASTM tested for slip resistance under both dry and wet conditions. Its tensile strength is 10 times greater than 30-pound felt, it covers up to five times the amount of roof space per roll, and it is 10 times lighter than 30-pound felt, says Bob Dahl, senior vice president of construction and specialty products for Typar. Surround SR can be left uncovered for up to six months, and it's waterproof.
"We were seeing the reluctance of the roofing industry to move to a synthetic offering," Dahl says. "We've been able to develop a product that provides these properties [of synthetic underlayments], but at a better price point."
Alan Hubbell, new construction marketing manager for DuPont Building Innovations, predicts more people will move to synthetic underlayments.
"I was just at the recent International Roofing Expo, and there were a lot of synthetic underlayments out there. We know it's a growing category," he says.
Last October, DuPont introduced its synthetic RoofLiner with Evaloy. It offers improved durability and slip resistance over its older synthetic product.
"We have a twisted tape that goes in two directions and provides a higher friction component, and coating materials for slip resistance," Hubbell says.
CertainTeed also stresses slip resistance with its new synthetic product, DiamondDeck.
"It's got a fiber surface, unlike most others in the marketplace," Paul Batt, says director of product marketing for CertainTeed. "It has very good wet and dry traction."
Felt underlayment's appeal lies in its familiarity and low cost. As a result, dealers and distributors will need to educate customers on the features and benefits of the new products: their non-skid surfaces, increased safety, and convenience, says James Groff, chief marketing officer for Wolf, a distributor that recently started handling Opus' underlayment. "There will be a percentage of people who are interested in moving to a product that, while more expensive, outperforms the norm," Groff predicts.
Synthetic underlayments, particularly ice and water barriers, also may see a boost in popularity because of an increased desire to protect homes' interiors from being damaged by bad weather. Many building codes in the North already specify the use of such waterproof underlayments, but Bert Elliott, product manager at Owens Corning, says he has noticed synthetics being used in warm climates.
"We're seeing more and more of this product used in the South where you don't get any ice, because it self-adheres to the deck and gives more protection," he says. And while ice and water barriers originally were promoted for use around eaves and valleys, Elliot has noticed them being used in Florida underneath the entire roof system.
"The idea is if you should ever have a hurricane or lose part of your roof, you have secondary protection," Elliott says.
CertainTeed has also noticed this trend, and plans to introduce more products geared to hot-weather sites. One such product, MetaLayment, is specifically designed for metal roofing and can withstand temperatures up to 250 degrees Fahrenheit.
Elliott says Owens Corning's WeatherLock Mat is particularly popular in the South. It works with asphalt shingles, wood shakes, and quarry slate roof assemblies and prevents damage caused by wind-driven rains and other water flow, the maker says, and is also Miami-Dade County approved.
NRCA's Kirby also recognizes the added benefit of using ice and water barriers in warmer climates.
"Putting it in is a great way to prevent even that once-in-three-years snow," he says. "It makes people think 'I can spend just a little bit more.' ... and you've covered a lot of your risk a whole lot more."
However, he has some warnings against completely covering a roof with ice and water barriers.
They could work as added hurricane protection, he explains, but when it comes time to repair the roof, the whole roof deck may have to be removed if the waterproof underlayment cannot be taken off. Also, in areas that need heating, covering your whole roof with an ice and water barrier may result in water damage.
"In the Florida region, you're pretty much using your air conditioning, so that's generally going to be OK," he says.
Like synthetics, waterproof underlayment may cost more than simply using felt, but Batt says some homeowners are willing to make that sacrifice for improved safety.
"They are more expensive, no doubt. It costs more," he says.
"But when you explain the benefits to homeowners, they are typically willing to pay more for the underlayment under the roof."