Metal Up Close: Insulated Panels

by Jim Austin

When it comes to insulated metal roofing panels, the value comes from the R.
For those installing insulated metal roofing panels, or foam core sandwich panels, or pre-insulated metal panels, they mostly are prescribed for R-value — a measure of the capacity of a material (usually some form of insulation) to impede heat flow. The insulation material may vary, but works well combined with a metal roofing panel.
“Traditionally, insulated metal roofing panels have been used extensively in temperature and humidity controlled environments, such as food processing and storage facilities,” says Paul Collyer, a sales and technical consultant with Metecno-API. “However, in recent years the largest use has been for commercial and industrial structures of all types. As energy costs have increased, people are searching for more energy efficient methods of construction, particularly as it relates to the roof, which for many low-rise buildings is the biggest source of heat gain and loss. Today we see insulated foam core roofing panels used in every market segment of construction, and particularly in the pre-engineered building sector, which encompasses a wide variety of end users.”
Bob Sterling of Centria says insulated metal roofing panels, like his company’s Versapanel, are best suited for straightforward applications where high R-values are desired, mainly for large industrial structures. Because it can be installed in larger sections, it can be a cost-effective installation. Sterling says the Versapanel is suited for applications where long spans are required. The concealed fasteners provide a clean uninterrupted surface. He says Versapanel combines the beauty of a metal roof, weatherproofing, insulation, and structural deck in a single, factory-built panel system.
Not every structure calls for an insulated panel, but there are a variety of practical applications. “In terms of insulation efficiency, the best possible place for building insulation is the exterior of the structural components,” Collyer says. “This allows the insulation to be continuous over structural elements without thermal shorts, and prevents condensation, which can develop in cavity based insulating systems. As insulated panels are rigid (non-compressible) and provide continuous foam-to-foam contact along each dimension of the panel, they provide maximum thermal effectiveness.”
Jay Smith of Metl-Span says insulated metal roof panels can be used in almost all applications like manufacturing facilities, industrial buildings, warehouses, multi-family housing, aircraft hangars, schools, athletic facilities, natatoriums, cooler facilities, food processing plants, and many others. “Any part of the country can and will benefit from the use of an insulated metal roof panel,” he says. “With the highest insulating value of all insulation products commercially available, this will lead to lower operation cost to any building owner.”
That’s an attractive selling point. Insulated panels are environmentally friendly, as the primary components (steel and foam) are composed of recycled content. Panels themselves can be recycled, and are often used in LEED certified projects.
“We see extensive use across all climactic conditions, literally from the North Pole to the South Pole and everywhere in between,” Collyer says. “People are looking for roofing systems that provide the best possible interior comfort level for the lowest energy expenditure. The greater the seasonal temperature variation in terms of heating/cooling degree days, the greater the need for high R-value roof systems. However, with current energy codes getting tighter all the time, such as the new California Energy Code Title 24, insulated panels are being used on a regular basis in even moderate temperature locations. The lifecycle cost benefits are significant, and as the old commercial used to say, ‘you can pay us now or pay the energy companies later.’”
Obviously, insulated metal roofing panels are delivered to jobsites ready for installation. The manufacturer takes care of all assembly and sizing of panels. Manufacturers contend installation isn’t all that difficult.
“For the most part they are installed the same way as a single skin metal roof, except that some sort of lifting equipment may be needed if long panel lengths are required,” Smith says. “Since an insulated metal roof panel is a structural panel, they can be used as working (walking) platform once they are installed. Metl-Span offers installation guides, videos, and can provide onsite technical assistance if required.”
Like the manufacturers of almost all metal roofing products, those manufacturing insulated panels are careful to ensure installers have the proper knowledge to do the job right. Collyer says Metecno-API is very thorough.
“Insulated panels are typically installed over light-gauge steel purlins or steel joists,” he says. “Spanning characteristics of the panels are available from the manufacturer, and take into account temperature differentials, wind loads, live and dead loads. Deflection characteristics are also calculated to make sure they comply with building codes. Manufacturers test their panels for compliance with wind uplift and fire testing to meet the standards of a Class A roof assembly. Recommended minimum slopes are typically 5:12.”
Collyer says it’s important to remember that although typical attachment methods of these systems provide a small amount of shear resistance, they should be treated from a design standpoint as a cladding system only and not as a shear panel. He says metal-faced foam core roofing panels are not the same as structural insulated panels, which do provide meaningful shear resistance. “Suitable cross bracing utilizing cables, strapping, rods, or angle iron within the roof framing should be relied upon to provide the necessary diaphragm action of the roof assembly,” Collyer says. “As compared to single skin metal roofing with batt insulation, foam core insulated panels themselves are no more difficult to install, but may require slightly more labor in handling the panels because being a composite, they are heavier.”
Collyer says the biggest savings come when R-factor requirements dictate the need for multiple layer roof/insulation systems, such as standing seam roofs with fiberglass over and between the purlins, separate vapor barriers, strapping, basket systems, thermal blocks, etc. “This is because foam panels are installed in one step,” he says. “Even though the material costs are slightly higher than the multi-component systems listed above, the in-place cost of foam panels is generally very competitive.”
That’s a selling point to contractors looking to take their business in another direction. A contractor capable of effectively installing insulated metal roofing systems can create a niche for himself in his market. And because insulated panels provide a variety of insulation and come in a variety of thicknesses, there are plenty of opportunities.
“Most all insulated metal roof manufacturers produce panels in thicknesses of two to six inches in one-inch increments,” Smith says. “Typically anything thicker than three-inch is used for refrigerated buildings such as food storage or food processing.”
Sterling worked closely with Centria’s project at Lincoln Financial Field in Philadelphia, home of the NFL’s Eagles. “For installations like at Lincoln Financial Field, it provides an attractive look, including a finished interior, and it’s capable of handling high wind loads, he says, adding the installation was made easier because sections were hoisted into place as a large piece. Versapanel double tongue-and-groove joinery, trapezoidal side seams, concealed clip system, and snap-on caps provide unsurpassed protection against moisture infiltration and leaks. Sterling estimates the choice of the Versapanel for the Lincoln Financial Field project saved approximately $3 a square foot — or almost quarter-million.
“Foam core roofing panels in the industry typically range from 1.5 inches to 6 inches, and are composed of a modified urethane foam core, also referred to as polyisocyanurate, which for purposes of this discussion can be considered the same,” Collyer says. “In moderate climates, 4-inch thick panels (R-33) provide more than enough insulation for commercial/industrial structures. Panels 5-6 inches thick are typically used only for cooler/freezer buildings or commercial/industrial projects located in extreme climate zones, like Alaska. It is also very important to note that the thermal efficiency of foam panels is maximized because the insulation is not compressed during installation, unlike fiberglass for instance. Sandwich panel R-values are often determined by in-place testing procedures, which result in true, installed R-factor roof assemblies.”
Collyer says while the overwhelming majority of insulated metal roofing panel applications are for cold storage and commercial/industrial applications, Metecno-API provides product for a handful of custom, higher-end large residences each year. “The biggest reason insulated metal panels are not used for residential construction is that the logistics of residential construction do not lend itself well to this product,” he says. “The typical house is relatively small, custom in nature, the contractor base is too large and the engineering and detailing coordination required for a successful installation is too complex.”

Source constructionmagnet.com

LEED points through photovoltaics

by Kevin Corcoran and Gene Johnson, Englert, Inc.

Renewable energy from the sun can provide building heat and power needs through solar electric and solar thermal technology using the sun to directly generate electricity with rooftop-mounted photovoltaic cells or by using the sun to heat domestic hot water — all with standing seam metal roofing. This meets the requirements of LEED Energy and Atmosphere Credit 2 (Renewable Energy), which incrementally awards up to three points for generating 5 percent, 10 percent, or 20 percent of the building’s energy use with renewable power.
These building-integrated photovoltaics provide increased value by simultaneously serving two purposes: power generation and architectural function.
Using solar energy to heat domestic hot water is more commonly implemented on residential buildings but because of rising conventional fuel costs and because of its relatively short payback, solar water heating is increasingly seen as a means of offsetting the cost and difficulty of generating grid-based energy.
However, because the efficiency gains created by solar thermal technology do not in fact generate power, they are not considered part of the Credit 2 renewable category, but are instead captured by LEED Energy Credit 1.
Most architects recognize the value of solar technologies but have been leery of the aesthetics of highly visible collectors mounted on roofs. While solar power historically has been synonymous with environmental consciousness, traditional types of solar systems have been avoided because of their unattractive design.
Either the technology was cumbersome and expensive to install or there simply was not very much interest among builders and homeowners to use solar despite a myriad of local, state, and federal development and tax incentives around the country.
That picture may be changing. New photovoltaic and solar thermal technologies are emerging that are much simpler to install and have been designed to work specifically with standing seam metal roofing. Recent breakthroughs in PV design and thermal technology have produced materials that are attractive, effective, and virtually invisible to the naked eye.
Even some of the older crystalline PV technologies that required the installation of box-like crystalline arrays are changing. A chief concern was how the photovoltaic modules could be attached to metal roof systems without jeopardizing material and weathertightness warranties. One answer is a novel clamping technology, called S-5! for standing seam metal roofing. The attachment clamp and its attendant round-point setscrews enable the entire installation without a single penetration through the surface of the metal roof, even with thousands of individual attachment points.
But the newest photovoltaic material is an extremely lightweight and unbreakable self-adhesive laminate material less than a quarter-inch thick that is attached to standing seam panels with a hand roller. They are made exceptionally durable by encapsulation in UV stabilized polymers. The polymer encapsulation is partially constructed of durable ETFE. The material is bonded to conventional standing seam roofing panels for use on any south facing roof with good solar access or to structural standing seam panels for shops, barns, and sheds. The laminates can be attached before or after the standing seam panel has been installed and in many cases, provides all the electricity a building needs.
The newest solar thermal collection system is comprised of a 1-inch thick conductor that employs glycol protected fluids to collect and transfer solar energy to building systems using closed loop heat exchange technology. The system is concealed under the standing seam metal roof laminated with the amorphous silicon PV system. Upon completion, the solar thermal system becomes an integral part of a hardened building envelope that provides storm resistance, energy security, and lower operating costs by replacing fossil fuels and electricity with solar energy.
Because they are fully integrated, they reduce cooling loads on buildings and can directly contribute to process and space cooling by dissipating excess heat through radiational cooling.
Building owners can realize immediate benefits from the reliability and operational simplicity of these modern integrated mechanical systems.
Another reason why the integration is occurring rests with the individuals who are installing it. Architects who espouse rooftop photovoltaics for environmental reasons and to gain lucrative tax and building incentives are finding roofing and electrical contractors who will install the rooftop installations quickly and efficiently. They are realizing the need for both to work together not only for installation reasons but to be able to offer commercial and residential building customers metal roofing and solar warranties at the same time. Architects interested in solar would do well to find the major electrical and roofing contractors doing solar installations in their markets. They are generally the first installers you would talk to once a building has been specified with photovoltaics on a metal roof. In some cases the manufacturer will also provide installation.
Many architects and builders active in the U.S. Green Building Council program already know that buildings with standing seam “cool” roof material can generate seven LEED credits for heat transfer, reuse, and recyclability — a major step in accumulating enough points to earn government and public utility financial incentives for a project.
But metal roofing can also be a major stepping-stone to several other LEED credits, in the category that PV and thermal energy roofing materials apply to — Energy and Atmosphere-Credit 2 — Renewable Energy. There are up to three points awarded for this category, based on the amount of renewable energy the building produces. The requirements are to supply at least 5 percent (one point), 10 percent (two points), or 20 percent (three points) of the building’s total energy use through on-site renewable energy systems. Another possible credit category is Energy and Atmosphere-Credit 1 — Optimize Energy Efficiency. There are up to 10 points awarded in this category, based on percentages of energy cost reductions. For example, a 60 percent reduction will earn the maximum 10 points and is likely attainable with use of a metal roofing system with an integrated photovoltaic system. The project team gains a credit for successfully demonstrating energy cost savings of 10.5 percent and one point for each additional 3.5 percent of savings.
Sophisticated computer modeling tools utilizing computational fluid dynamics (CFD) calculations help designers reduce uncertainty and unpredictability in using these strategies to complement or replace forced air ventilation, qualify for LEED credits, and for tax incentives and rebates.
In effect, before a building project can be considered for LEED certification, the project team first must show the building and its systems meet the energy standard’s compulsory conditions for compliance. The team also must prove compliance with whichever criteria is most rigorous; cost savings are determined by comparing the performance of the proposed building design with that of the baseline design, which meets specific prescriptive requirements
The amount of electricity produced by a PV system is based primarily on the size of the system, but the output of the array will depend on climate and geographic orientation, amount of sunlight available at the location, the slope of the roof, its orientation with respect to due south, and other considerations not affecting the system itself include local utility rates, tax credits, and maintenance.
Typically, the energy payback time for PV systems is five to 10 years. For this reason, integration with a metal roof becomes a critical factor. Given that a well-designed and maintained PV system will operate for more than 20 years, it is almost natural they would be combined with standing seam metal roofing systems that offer the same kinds of longevity, often backed by warranties. Unlike other forms of roofing material that must be replaced in 20 years or less, metal and PV will often operate for close to 30 years, producing far more energy over their lives than was ever used in their manufacture. Unlike sheet-membrane roofs that may require replacement before the usable life of the PV expires, the standing seam metal roof has a life expectancy consistent with that of the crystalline modules, laminates, and the solar thermal system. Homeowners won’t be forced to dissemble the entire system when a shingled or flat roof begins to deteriorate several years after installation. PV system reliability and durability are outstanding — typical PV systems may last 30 years with minimal maintenance.
And there are also many grants and tax credits that come with the installation of PV and standing seam systems.
For example, net-metering states require utilities to buy back any surplus power generated on-site. In New York, the Green Building Tax Credit for business and personal income taxpayers provides a 100 percent photovoltaic for the incremental cost of building-integrated photovoltaic systems or 25 percent of the incremental cost of non-BIPV units and California offers a 7.5 percent credit against the cost of an installed solar energy system. Many more states, and the federal government, offer incentives and grants as well.
More than 20 states provide tax incentives in support of renewable technologies. Eighteen states have public benefits programs that have active energy efficiency and renewable energy programs.
The opportunity for architects to introduce new rooftop energy saving technologies and expand their business is unquestionably there. And while it may not represent the bread and butter of their business, it is an area of growth worth investigating.

Kevin Corcoran, vice president of business development at Englert, is a 27-year veteran of the metal roofing industry and has been responsible for introducing scores of metal roofing products and programs to builders and architects during his career.

Gene Johnson is a chemist and manager of quality, safety, and environment at Englert. He has more than 30 years of experience in developing and analyzing metal roofing materials and their coatings for residential and commercial building applications.

Source constructionmagnet.com

Not your father's underlayment

by Mark Ward Sr.

With metal roofs gaining market share in both the residential and commercial construction markets, a growing number of roofing product manufacturers are offering new synthetic underlayments specifically geared to the requirements of metal roofers. Among their arguments: Metal roofs are lifetime products that need lifetime underlayments, and the higher temperatures generated beneath metal roofs require underlayments that can take the heat.
“Contractors and installers are selling metal roofs today by telling customers these roofs are lifetime products,” observes Sal Catanese, manager of underlayments for Philadelphia-based Drexel Metals Corporation, “but standard felt underlayments won’t last as long as a metal roof does. Synthetics let you sell a lifetime metal roof with a lifetime underlayment.”
For one thing, Catanese points out, felt underlayments can rip or tear when exposed to high winds and severe weather — even before the roof goes on. After the metal roof is installed, he notes, temperatures under the roof “can get pretty high so that felt, which is soaked with asphalt, can melt and stick to the underside of the roof.” As successive heat and cold causes the felt to melt and then reform, degradation of the underlayment can occur.
Synthetic underlayments avoid these problems, Catanese says. RoofTopGuard II, distributed exclusively by Drexel, is made from multiple layers of polyethylene and polypropylene and can withstand exposure to sun and weather for up to four months. After the metal roof is installed, the product is rated for temperatures of up to 260 degrees. Given its temperature performance, he says, roofers can install the underlayment without using the additional rosin-paper slip sheet required for felt.
Though synthetic underlayments cost more than felt products, Catanese says, “customers who pay for the quality of a metal roof are also willing to pay for the added value of synthetic underlayment.” Yet he believes the price differential is shrinking. “Felt is soaked with asphalt, a petroleum-based product,” he points out, “and as oil prices rise then so does the cost of felt underlayments.”
Where synthetics once cost twice as much as felt, Catanese now puts the difference at only 50 to 75 percent. And compared to the overall price of a metal roofing job, he says, the underlayment is not a major cost. Metal roofers should also look beyond the up-front cost, he points out. Because felt is soaked in asphalt, the product can be very heavy. Catanese notes that RoofTopGuard II is five times lighter than 30-pound felt, so that a five-foot-wide roll weighs only 43 pounds.
The lighter weight not only makes synthetics easier for crews to hoist and carry, but allows rolls to be manufactured in wider widths. “Felt rolls are usually three feet wide because that’s about the most weight a person can carry and handle,” Catanese explains, “but you can easily carry a five-foot-wide synthetic roll, which helps you install underlayments faster and easier,” reducing labor costs. RoofTopGuard II is also designed with a “fiber-grip” skid-resistant surface for safety, and made to maintain a waterproof seal around nail fasteners.
Though peel-and-stick synthetic underlayments are on the market, Catanese believes the jury is still out on how the adhesives will hold up over the long term. RoofTopGuard II is mechanically fastened with cap-nails driven by a standard pneumatic gun. “But in the North where snow and ice damming is a problem,” he adds, “you could use peel-and-stick products as shields around valleys and eaves, and use our product for the balance of the roof.”
Though felt underlayments are still the standard in the United States, Catanese predicts that “felt has had its day, but its market share will continue to erode.” Some manufacturers of felt products are trying to devise performance enhancements, he notes, “but that only makes the felt more expensive and takes away from its only advantage, which is price.”

Mechanical or Peel-and-Stick
TAMKO Building Products of Joplin, Mo., offers two synthetic choices for metal roofs.
TW Metal and Tile Underlayment, along with TW Underlayment, are self-adhering rubberized asphalt sheet membranes faced with polymer film. TW Metal and Tile is reinforced with fiberglass, while TW Underlayment comes in at 40 mils thick.
“The products are great when you need to prevent water penetration, and they can also provide secondary protection against water penetration after installation of a metal roof system,” says Dan Hollabaugh, general manager for waterproofing, industrial sales, cements, and coatings at TAMKO. By contrast, he adds, “Felt underlayments don’t have any adhesive, so water can wick underneath them. And they’re more susceptible to wind damage when they’re exposed to weather, because felt is only nailed or stapled down.”
The two TAMKO products are rated for up to 90 days of UV exposure and, after the roof is put on, can withstand temperatures of at least 245 degrees. As peel-and-stick underlayments, Hollabaugh continues, “They’re good from an installation standpoint because it requires less time and labor than underlayments you have to nail down, you don’t have to put holes in the decking.” Installers will also appreciate the textured surface which provides skid-resistance for safety.
“Alternatives to felt underlayment have been around for a long time,” Hollabaugh reports, “but in the last five years or so, interest in peel-and-stick synthetic underlayment has really taken off. Though it costs quite a bit more than felt products, sales of peel-and-stick underlayment continue to grow because people are willing to pay for proven performance.”
Two choices of synthetic roof underlayment, both made of 100 percent polypropylene, are also available from Kirsch Building Products of Simi Valley, Calif. According to president Mark Strait, the company’s Sharkskin Comp is designed for asphalt roof installations and Sharkskin Ultra for metal, slate, and tile roofing systems.
“A one-product-fits-all approach hasn’t worked well in the marketplace,” Strait explains, “and so we’ve geared Sharkskin Comp to the more price-sensitive asphalt roofing market, and made Sharkskin Ultra for the high-performance market.” The Ultra product, for example, is rated for up to 12 months of weather and UV exposure. “Last year there was a metal shortage, while in Florida people had to wait on deliveries of roof tiles,” he recalls, “and so you might need your underlayment to stand up for more than just three or six months.”
Sharkskin Ultra has also been designed with higher abrasion resistance, plus a fastening system that eliminates the need for plastic cap-nails. “When you’re putting on a metal roof, and if your underlayment is fastened with cap-nails,” Strait suggests, “it can produce visible dimples in the skin of the metal, which isn’t very aesthetic.”
For Strait, the case for synthetic underlayment with metal roofs comes down to two considerations: pre- and post-installation. In the pre-installation phase, synthetics remain solidly on the roof while felt products “can easily get torn or ripped off in high winds, so that you get water damage,” he says. In the post-installation phase, he continues, “Metal roofs often have 50-year warranties and may last indefinitely, and so a long-lasting underlayment is a necessary complement. Also, if for some reason the primary roof fails — maybe in a hurricane — synthetic underlayment can provide secondary protection from water penetration.”
Compared to the overall cost of a metal roofing system, “it doesn’t cost you that much more, proportionately, to use synthetic underlayment instead of felt,” Strait says. He agrees that asphalt-laden felt underlayment can stick and unstick to the underside of a metal roof during episodes of heat and cold, so in time the felt can deteriorate. “Also, felt is organic,” he observes, “which means that when moisture is present you can get mold.”
Like most other synthetic underlayments, Sharkskin is made to be slip-resistant. But which product on the market really offers the most walkability? “Ask your distributor for samples of different underlayment products,” Strait advises, “and before you order anything, test them in the field, particularly when they’re wetted down as in a morning dew. In a lot of markets, the choice of synthetic products is driven by pressure from distributors. But you should test the different underlayments yourself and decide what you want.”
Metal roofers can evaluate synthetic underlayments by grouping them into twos, says Strait. The products are either mechanically-fastened or self-adhesive, and are either made of polyethylene or polypropylene. “Mechanically fastened underlayment usually allows for longer exposure to sun and weather than does peel-and-stick products,” he contends. “In addition, mechanically-fastened underlayment usually costs less, installs faster, and can be removed if the homeowner decides to remodel.”
As Strait sees it, the asphalt adhesive in peel-and-stick underlayments “can dry out over time and become less elastic — and it’s still undetermined how well these products will adhere over the long term and how the adhesive will stand up to UV exposure.” In the short term, he adds, peel-and-stick underlayments may “take some time before the adhesive is fully effective, which can be a problem if you have high winds.” Further, he says, though self-adhesive products are “seen as offering better sealing around nails, is that true over the long haul?”
The adhesive itself adds weight to a roll of underlayment, Strait continues, which makes the product more difficult to handle. And compared to mechanically-fastened underlayments, peel-and-stick installation is slower “because it takes two people to keep it straight. It’s like doing wallpaper. You have to start at the eave of the roof and roll it out straight. For one thing, being on the eave of a roof with a heavy roll of underlayment isn’t the best situation. For another, if the roll gets slightly askew or buckles, you can’t pull it off the deck and start over. Instead, you have to trim the underlayment in order to compensate.”
Strait concludes that self-adhesive underlayments “aren’t designed for the entire roof” but can provide ice and water protection in areas such as valleys, eaves, and dormers. Moreover, he characterizes polypropylene is being less sensitive to temperatures and more stable than polyethylene.
“Another reason to check out samples of different products,” Strait relates, “is the fact that synthetic underlayments are still in an early stage of development. You can’t just develop a product and throw it up on the roof. Some manufacturers are less knowledgeable than others. There are a lot of new companies out there with synthetic underlayments and so I think there’s eventually going to be an industry shakeout.”
Strait advises that, despite manufacturers’ claims about high temperature ratings, roofers can encounter “a lot of marketing jargon.” He tells roofers to “make sure the product has been tested and been approved by the International Code Council and regional code bodies. Also, some manufacturers’ warranties are voided once the underlayment is penetrated — even by a fastener. So be sure and get some references from other people who’ve used a synthetic product, before you buy.” Sharkskin is rated, he says, for a softening point of 230 degrees and a melting point of 300 degrees.
“The construction industry is slow to change,” Strait believes, “but the old technology of felt is becoming more inferior to synthetics. Synthetic underlayment provides better performance and more productivity, and perhaps fewer workers comp claims because your crews aren’t lifting heavy rolls. And as oil prices go up and the cost of asphalt rises, then felt will lose its only advantage, which is price.”

Synthetic Sales Growing
Though Berger Building Products of Feasterville, Pa., brought out its Pro-Master Roof Shield UDL synthetic underlayment only 18 months ago, “sales are definitely on an upward trend,” reports sales and marketing manager Michael Pietrzak. “Even though price is always an issue in the construction industry and roofers have been using felt forever, our synthetic product is gaining awareness.”
Felt underlayment continues to enjoy a price advantage over synthetics, but Pietrzak describes the difference now as “slight” because petroleum prices are rising and asphalt-laden felt is becoming more expensive. But even at a higher price, synthetic products can save metal roofers money “by being quicker to install than felt, since synthetic underlayment is much more lightweight and therefore can be manufactured in wider rolls.”
A four-square roll of Pro-Master Roof Shield UDL weighs 11 pounds and a 10-square roll just 28 pounds, both about three times less than felt, Pietrzak says. Given the narrowing price difference between felt and synthetics, he believes roofers can now consider using synthetic underlayment for all roofing applications — whether metal, slate, tile, or asphalt. The Berger product, he continues, is anti-slip-coated for safety and UV-stabilized for up to one year of exposure. “In storm-damaged areas there can be shortages of shingles,” he notes, “and so the exposure rating is very important.”
High performance under even prolonged exposure, as well as long life after the roof is in place, are features of Titanium-UDL and Titanium-PSU synthetic underlayments from InterWrap Inc. of Mission, B.C. “Roofing products have to be really durable, since roofing construction is an extremely challenging application,” says Gary Schinning, division manager for roofing products.
“Think about what roofing jobs are like,” he continues. “Crews are walking and working on the underlayment, and the people often carry heavy loads and have to twist and turn their feet. Felt can rip and tear, or blow off in a high wind. But synthetics can take it, and are also slip-resistant to help keep workers safe.” InterWrap’s UDL product features SURE-FOOT, a nodular surface for walkability even on wet or steep roofs.
Schinning states that Titanium-UDL is six times lighter and 20 times stronger than standard 30-pound felt. A 10-square roll weighs 45 pounds, compared to 225 pounds of nominal weight for an equivalent roll of felt. “Put another way,” he points out, “you get 10 squares of coverage, for the same weight as only two squares of 30-pound felt.” Because of the light weight, plus a 48-inch width and 250-foot run length, he estimates than InterWrap’s underlayment can be installed at least 50 percent faster than felt.
“You’ve got fewer laps, cuts, and less roll handling,” Schinning relates. “Also, you don’t need a slip sheet because our product forms a barrier to air, water, and vapor. And since the roll is wider than a felt roll, you don’t need as many fasteners. All of that means you can do more jobs in less time, inventory fewer rolls, and enhance your productivity and profits.”
Titanium-UDL is mechanically fastened, while Titanium-PSU is a peel-and-stick product used in valleys, eaves, and with metal flashing for extra protection against water and ice damming. Once installed, the underlayments are rated for up to six months of UV exposure. Then after the roof is put on, the InterWrap products can withstand temperatures ranging from 70 degrees below zero, to a high of 212 degrees.
“Since the underlayment is synthetic,” Schinning notes, it’s unaffected by water, and it’s mold-free, lays flat, won’t wrinkle, and you can leave your roof uncovered without the need for tarps or immediate dry-in. And unlike felts, it doesn’t dry out, crack, or leach oils in the heat, and it doesn’t become stiff, difficult to unroll, or crack in the cold.” Titanium-UDL has also been certified under the ASTM D1970 standard for nail sealability since the product is engineered to form a polymer seal around approved nail fasteners.
Schinning acknowledges that synthetic underlayments cost about 75 to 100 percent more than equivalent felt products. “Unlike felt,” he adds, which “uses the cheapest materials and involves only one manufacturing step,” he explains, “the process to make synthetic underlayment requires several steps and costs more.” As a percentage of the total cost for a metal roofing project, however, “there’s not that much difference in total dollars to use synthetics instead of felt,” he adds. “Also, it’s been reported that labor savings can wipe out the cost difference. And besides, metal roofing customers want quality and a lifetime product.”
Those performance qualities, Schinning contends, also make synthetic underlayment a product that contractors could use under any roofing material — copper, zinc, galvanized steel, aluminum, slate, tile, synthetic tile, clay, cement, cedar shake, or asphalt. “Sales of synthetic underlayment will continue to grow,” he predicts, “and the growth will come at the expense of felt. Just as homebuilders today couldn’t imagine going back to the days before house wrap, someday contractors will use synthetics and wonder how they used anything else.”

Source constructionmagnet.com