GAF Underlayment & Deck Repair Nationwide

GAF Underlayment & Deck Repair: The San Antonio Owner’s Guide

If you’re searching for GAF underlayment and deck repair in San Antonio, here’s the direct answer: most underlayment replacement jobs on San Antonio homes run between $400 and $1,800 installed, while deck repair (the plywood or OSB beneath your shingles) typically adds $75 to $110 per 4×8 sheet when rot is found. We stock GAF-compatible underlayment on our trucks, and a typical repair takes one full day. Most San Antonio homeowners discover the problem during a leak investigation or a shingle replacement, when our crew lifts the old material and finds the deck or underlayment has quietly given out underneath.

Call (903) 354-7802

Underlayment is the water-shedding layer between your roof deck and your shingles. When it fails, water reaches the deck. When the deck fails, you have a structural problem, not just a cosmetic one. Erik Lindgren and our crew at Birchbark Roofing San Antonio have opened up plenty of San Antonio roofs where the shingles looked fine from the street but the deck underneath was soft enough to push a screwdriver through. That’s the repair you’re here about.

Which GAF Models This Applies To

GAF makes several underlayment lines, and the right choice depends on what’s already on your roof and what your shingle warranty requires. The three you’ll most commonly see in San Antonio are Deck-Armor, Tiger Paw, and StormGuard. Deck-Armor is a breathable synthetic underlayment rated for high-temperature exposure, which matters here in San Antonio where attic temperatures can push 140°F in August. Tiger Paw is a high-traction synthetic used where roof pitch makes footing tricky. StormGuard is a self-adhering ice-and-water shield that goes at eaves, valleys, and around penetrations.

The compatibility gotcha most homeowners miss: if your roof carries a GAF enhanced warranty, the underlayment specified at installation must be matched when repaired. We can check your paperwork and confirm what’s required before we touch anything. For older GAF roofs installed before synthetic underlayment became standard, we typically recommend upgrading to a synthetic rather than patching felt, because San Antonio’s humidity and temperature swings punish felt paper faster than synthetics. We’re an independent San Antonio roofing contractor, not a GAF affiliate, but we work with their materials daily and stock Deck-Armor and StormGuard on the truck.

Signs Your GAF Underlayment & Deck Repair Is Failing

• Dark stains on ceilings below the roof. Water has passed through the underlayment and soaked into the deck. By the time it stains drywall, the deck around the leak is almost always compromised in San Antonio’s climate, where small leaks get accelerated by heat and humidity.
• Spongy spots when walking the roof. A soft deck means the OSB or plywood is losing structural integrity from moisture. If our crew feels deflection underfoot, that sheet comes out, no question.
• Granules washing into gutters after storms. Shingle wear exposes the underlayment to UV and direct water contact. GAF synthetics hold up longer than felt, but once they’re exposed, they’re borrowed time.
• Curling or lifted shingle edges near eaves. When underlayment fails at the lower roof edge, water wicks upward under the shingles. This is one of the most common failure points we see on San Antonio homes built in the 1990s and early 2000s.
• Visible daylight in the attic through the deck. If you can see light pinholes from inside your attic, the deck has gaps or rot. This is a straight-forward find on a clear day and worth checking before monsoon season rolls through the Hill Country.

Replacement Cost & What’s Included

Here’s what our San Antonio customers actually pay. Underlayment replacement without deck repair runs $400 to $1,800 depending on the roof size, pitch, and whether we’re doing the full slope or a localized repair. Deck sheet replacement adds $75 to $110 per sheet, and most San Antonio rot repairs need one to four sheets. The range is driven by three things: how many squares are being stripped, whether your roof has multiple layers to remove, and how steep your roof is. A two-story home off Huebner Road with a 8/12 pitch costs more than a single-story ranch in Harlandale with a 4/12.

Every estimate we write includes the tear-off, disposal, new GAF-compatible underlayment, deck sheet replacement where needed, re-nailing, and a written line-item price before work begins. No change orders, no surprise number at the end. The 365-Day Done Right Promise covers the repair: if it’s not right, we make it right. Erik Lindgren walks through every number on the estimate with you before anyone climbs the ladder.

DIY or Call Us?

We’re honest about what a homeowner can reasonably do. You can check your attic for daylight pinpoints, look for water stains, and keep an eye on your gutters after storms. That’s useful information and it helps us diagnose faster when you call. What we don’t recommend is pulling shingles yourself to inspect decking. There’s a reason roofers work in teams on a San Antonio roof in July: the heat, the pitch, and the risk of opening a section you can’t safely close before rain. A poorly patched section of underlayment is worse than the original problem, because water now has a direct route to the deck.

If you have a leak or suspect deck damage, call us at (903) 354-7802. We’ll inspect it, show you what we found, and hand you a written price. If the dog needs to stay inside while we’re up there, we’ll coordinate the door schedule with you.

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