Self-adhering underlayment is a rubberized asphalt (polymer-modified bitumen) membrane with a sticky back that bonds directly to the roof deck and seals around the nails driven through it. On a Colorado Springs roof it belongs at the eaves, in valleys, along walls and chimneys, around skylights and pipes, and across the whole deck on low slopes. PPRBD requires an ice barrier at the eaves only on homes above 7,000 feet, but we treat these spots as the leak-prone parts of every roof.
How it differs from felt and synthetic underlayment
| Underlayment | How it attaches | Waterproof at nails? | Best use |
|---|---|---|---|
| Asphalt felt (#15, #30) | Nailed or stapled | No | Field of the roof on older systems |
| Synthetic | Nailed with cap fasteners | No | Field of the roof; lighter and more tear-resistant than felt |
| Self-adhering membrane | Bonds to the deck | Yes, seals around nails | Eaves, valleys, walls, penetrations, low slopes |
Felt and synthetics shed water that gets past the shingles. A self-adhering membrane stops water even when it is pushed sideways or uphill, which is exactly what happens behind an ice dam or in a valley full of slush.
Where we install it on a Colorado Springs roof
- Eaves. Snow melts over the warm part of the house and refreezes at the cold overhang. The membrane keeps backed-up water out of the wall and ceiling.
- Valleys. Two slopes pour water into one channel. We line valleys with the membrane, with or without metal on top.
- Wall intersections and chimneys. Installed on the deck before the step flashing and counterflashing go on. On a replacement, short pieces slide under existing wall flashing more easily than a full roll.
- Skylights and pipe penetrations. A collar of membrane under the flashing backs up the flashing itself.
- Low slopes. From 2:12 up to 4:12, water drains slowly and can travel uphill by capillary action. Covering the whole low-slope area is the safest build. See planning your roof’s slope for the pitch limits.
These locations are written into the Integrity Roofing System, our component-by-component standard for every replacement.
What PPRBD requires above 7,000 feet
Some homes in PPRBD’s area sit above 7,000 feet. PPRBD’s reroof guidelines require an ice barrier on properties above that elevation, made of either two layers of underlayment cemented together or a self-adhering polymer-modified bitumen sheet, running from the eave edge to at least 24 inches inside the exterior wall line. The elevation is printed on the permit receipt, so there is no guesswork. Note that 24 inches is measured inside the wall, not from the edge: on a home with wide overhangs, one 36-inch roll often falls short and a second course is needed.
Granulated or smooth?
Owens Corning makes WeatherLock in a granulated version with a slip-resistant surface and in smooth film versions. We prefer granulated product on steep slopes because crews can walk on it safely before shingles go on. Smooth versions lie flatter under some metal and specialty roofs. Both seal around nails.
Installing in cold weather
The adhesive grabs slowly in the cold. That gives a crew more time to position long runs in valleys, but it also means:
- edges may need fasteners until the sun warms the membrane;
- water can get under laps before they bond, so we dry the roof in the same day;
- dust or grit under the sheet can stop it from ever sealing, so the deck is swept clean first.
For winter projects in general, read how shingles seal after a winter install. Denver homeowners asking whether the city requires it should read our Denver ice and water shield guide; Denver does not.
Get your roof’s leak-prone spots checked
Integrity Roofing and Painting has installed roofs on the Front Range for years and has been family-run since 1990. We are veteran-owned and an Owens Corning Platinum Preferred contractor with 650+ Google reviews. If you are getting bids, ask each roofer exactly where the membrane will go and how far up the eaves; the answers tell you a lot. Call (719) 488-2800, book a free roof inspection in Colorado Springs, or read about Owens Corning products we install.
Sources: Pikes Peak Regional Building Department, Reroofing Guidelines (rev. 03/05/2024); Owens Corning, WeatherLock G granulated ice and water barrier and WeatherLock Flex installation instructions.
