Like a linebacker in football or a sentry and archer in a medieval castle, roof underlayment is a second line of defense.
This critical component, which, among other duties, guards against water and wind, is not always given the careful consideration it deserves, however.
We live in a world of options – and which particular underlayment product you choose for a roofing project can impact the quality and lifespan of that individual roofing system.
Asphalt-saturated roofing underlayment has been the go-to product for ages. Although this economical “traditional” felt is still widely used, contractors today also have a multitude of options available in the rubberized asphalt and non-bitumen synthetic categories.
There are many factors to ponder when considering roof underlayment, including climate, primary roof-covering material, ease of use, individual preference, and, of course, cost.
Synthetic roof underlayment may cost more than traditional felt but boasts durability, better walkability, prolonged exposure to UV, and a lighter weight. Crafted from synthetic polymers, this type of roofing underlayment does not absorb water the way traditional felt can and some can be left uncovered on a roof deck for up to 6 months without breakdown. That makes it a desirable choice for new construction where material delivery delays are possible.
Some roofers still prefer the old standbys of #15 and #30 traditional felt, though some companies have injected new life into these “old” felts. Atlas Roofing Corporation, for example, sells engineered roof underlayment: Gorilla Guard® EVERFELT™ 30 and Gorilla Guard® EVERFELT™ Spec 30.
Through a proprietary blend of powerful substrates, the manufacturer has delivered a product that is simple, durable and outperforms traditional felt in peel resistance strength, tear strength and weight.
Contractors also have at their disposal a number of self-adhering, weather-resistant roof underlayment options that can withstand the rigors of all roof applications. Looking for a secondary water barrier? These options can be used as flashing tape, too.
Maybe the concern is simply cost. Maybe the concern is wind-driven rain and ice dams. Or maybe it’s slip resistance. No matter the situation, there is an underlayment that’s best for a particular project. Don’t overlook that importance or the requirements of the primary roof covering’s manufacturer.
After all, roofing underlayment should not be out of mind even though it winds up out of sight between the roof deck and the main roof covering. Even though it’s not the primary defense for your roof, sometimes the second line is just as important as the first.