High-temp Underlayment
High-temp Underlayment | Metal Roofing | Roofing | Sweetwater
Feel the confidence of a roof that laughs at Sweetwater’s scorching summers—HEP’s high-temp underlayment is engineered to perform where ordinary barriers fail. Designed for seamless compatibility with metal roofing, our self-adhering membrane shrugs off up to 250 °F, stops wind-driven rain at the deck, and grips tight even on the steepest pitches. That means no bubbling, no slipping, and no nail-hole leaks—just rock-solid protection beneath every standing seam or rib panel.
Beyond brute heat resistance, this advanced underlayment installs fast and clean, saving labor hours while extending the life of your entire system. Whether you’re upgrading a historic Sweetwater farmhouse or building a modern warehouse, trust HEP to add an invisible shield that keeps interiors cooler, energy bills lower, and warranties intact. Get in touch today and discover how the right layer beneath your metal roofing makes all the difference.
FAQs
Why is a high-temperature underlayment recommended for metal roofing in Sweetwater?
Sweetwater’s long, hot summers and abundant sunshine can push the surface temperature of a metal roof well above 190 °F. A standard felt or synthetic underlayment can soften, wrinkle, or even melt at those temperatures, opening pathways for leaks. High-temperature (high-temp) underlayment is engineered with modified asphalt and fiberglass or polyester reinforcement that remains stable up to 250–300 °F. That extra heat resistance helps the underlayment stay flat and watertight despite intense solar gain, thermal cycling, and the expansion/contraction that occurs beneath metal panels.
What temperature limits does your high-temp underlayment handle, and how is it tested?
Our premium high-temp membrane carries an ASTM D1970 rating for sustained exposure up to 250 °F (121 °C) and short-term peaks of 300 °F (149 °C). The material is lab-tested for dimensional stability, tear resistance, and adhesion at those temperatures. Each production batch also undergoes a 90-day UV exposure test to confirm the surface film will not degrade during typical job-site delays before the metal panels are installed.
How does high-temp underlayment extend the life of a metal roof system?
1. Heat stability – It stays intact when the underside of the metal panels heats up, preventing premature failure of the roof assembly. 2. Self-sealing around fasteners – The rubberized asphalt layer flows slightly under heat, creating a gasket around screws or clips and stopping water intrusion. 3. Waterproof barrier – It provides secondary waterproofing if wind-driven rain is forced under the panels. 4. Corrosion protection – By separating the metal from any treated wood or dissimilar metals below, the underlayment helps prevent galvanic corrosion. 5. Reduced maintenance – Because the membrane stays flat and adheres tightly to the deck, it resists uplift and flutter that can fatigue panels and fasteners over time.
Can your high-temp underlayment be used on low-slope metal roofs or in valley and eave areas?
Yes. The membrane is approved for roof pitches as low as 1:12 when it is fully adhered to a clean, dry deck and seams are overlapped a minimum of 6 in. For valleys, eaves, ridges, and penetrations, the peel-and-stick backing seals tightly to form an ice-and-water shield, which is especially important in Sweetwater where occasional hailstorms and heavy rain can overwhelm standard lap seams.
Does installing a high-temp underlayment improve the energy efficiency of my building?
Indirectly, yes. While the membrane itself is not a radiant barrier, its heat-stable surfacing prevents degradation that could allow hot air or moisture into the attic. By keeping the roof assembly airtight and dry, it lets the metal panels and any reflective coatings perform as designed, reducing attic temperatures and lowering cooling loads. Many customers report HVAC energy savings of 5–15 % after upgrading to a properly vented metal roof with high-temp underlayment.
What is the installation process and what warranties are available?
Installation steps: 1. Prepare the deck: remove old nails/debris and ensure the surface is dry. 2. Prime porous plywood or OSB if required by the manufacturer. 3. Peel the release film and fully adhere the membrane, starting at the eave and working upslope. 4. Overlap horizontal seams 4 in. (6 in. on low slopes) and end laps 6 in.; roll firmly to activate the adhesive. 5. Flash valleys, hips, and penetrations with additional membrane strips. 6. Install the metal roofing within 90 days of underlayment application. Warranty: When installed by a certified contractor, our high-temp underlayment carries a 30-year limited material warranty that covers manufacturing defects and a 120-day exposure guarantee prior to panel installation. If purchased as part of our complete metal roof system, it also qualifies for an optional 20-year labor warranty against leaks.