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CertainTeed Underlayment & Deck Repair: The San Antonio Owner’s Guide
Most CertainTeed underlayment and deck repair jobs in San Antonio run $850 – $2,400 installed, depending on how much decking has to be replaced and which CertainTeed underlayment your roof was built with. We stock CertainTeed-compatible underlayment on our trucks and can typically start the repair within a day or two of inspection. Homeowners usually discover this problem two ways: a roofer doing shingle work calls out rotted decking beneath the felt, or a leak shows up indoors after a storm and the underlayment turns out to be the point of failure, not the shingles above it.
Key Takeaways
- Installed cost range: $850 – $2,400 for typical CertainTeed underlayment and deck repairs in San Antonio
- What we replace: rotted or delaminated plywood/OSB decking, plus the CertainTeed-compatible underlayment layer above it
- When you need it: decking has soft spots, water stains in the attic, or underlayment is torn during a reroof
- Warranty: every repair is covered by our 365-Day Done Right Promise, in writing, at no extra cost
Which CertainTeed Models This Applies To
CertainTeed doesn’t make one underlayment; they make a family of them, and the right repair depends on which one was installed. The two most common in San Antonio are DiamondDeck, a synthetic underlayment with a high-grip coating, and RoofRunner, a felt-based option that’s thinner and less expensive but more common on older roofs. There’s also WinterGuard, a peel-and-stick ice and water shield that matters more up north than it does here.
If you’re not sure what you have, don’t worry. We identify the material on site by reading any printed branding on the exposed edges or by examining the surface texture and thickness. DiamondDeck runs about 40 mils thick; RoofRunner is closer to 15 mils. The compatibility gotcha many San Antonio homeowners run into: a previous owner may have had a contractor substitute a generic synthetic underlayment without telling anyone, which affects which replacement material we match and how the new decking ties into the old felt.
Crestview Roofing Co San Antonio is an independent service provider and isn’t affiliated with CertainTeed. That independence matters because we’re free to recommend the right material for your roof rather than whatever a manufacturer’s distributor happens to have on the shelf. We also work with GAF and Owens Corning underlayments when that’s the better match for the existing roofline.
Styles & brands we work with
Signs Your CertainTeed Underlayment & Deck Repair Is Failing
- Soft spots on the roof deck. If walking the roof feels spongy in places, the plywood has absorbed moisture and started to delaminate. This is the most common failure we see after San Antonio’s spring storm season.
- Water stains on ceilings or attic rafters. Underlayment is the backup waterproofing layer. When shingles wear out and the underlayment has also aged out, water finds the seams and follows them indoors.
- Granular residue in gutters paired with damp attic surfaces. Shingles shed granules as they age, but damp attic surfaces below a visibly granule-shedding roof mean the underlayment has stopped doing its job.
- Torn or missing underlayment visible during a repair. We often find tears around roof penetrations or along rake edges where wind has lifted the shingles above and damaged the felt underneath.
- Buckling or wrinkled sections under shingles. In San Antonio’s heat, older felt-based underlayment can shrink and pull away from seams, creating channels where water pools instead of running off.
Replacement Cost & What’s Included
Here’s what the numbers look like in San Antonio right now. These are installed prices, including parts and labor:
| Scope of Work | Typical Cost |
|---|---|
| Small deck repair, single sheet of plywood (32 sq ft), new DiamondDeck underlayment | $850 – $1,200 |
| Moderate deck repair, 2 – 4 sheets, both decking and underlayment replaced | $1,200 – $1,800 |
| Larger repair, 5+ sheets, including re-nailing existing decking and new underlayment throughout the affected slope | $1,800 – $2,400 |
What drives the range is how much decking has to come out. Plywood that’s been wet for a month or two can often be saved; plywood that’s been wet for a year or more turns to something that crumbles when you pull a nail. The underlayment itself is relatively affordable, it’s the decking that adds up fast.
Every quote is a written price, delivered before any work starts. That number on the page is the number on the invoice. No change orders, no “we discovered more damage once we opened it up” phone calls. The 365-Day Done Right Promise covers the repair for a full year, including a free second visit if anything fails.
See the difference
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After
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After
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AfterDIY or Call Us?
Here’s the honest split. You can inspect your own attic for water stains, check for soft spots on a low-slope section you can safely walk, and look at whether underlayment is visible or torn around roof edges. That’s useful information and it helps you decide whether to call.
What you should not do is tear off shingles and replace underlayment yourself. This is a roof-access job, and San Antonio’s summer heat makes rooftop work riskier than most homeowners realize. Falls from ladders and roofs are the leading cause of home-injury fatalities, and a torn underlayment repair done wrong means water sitting directly on decking that was supposed to be protected. One misplaced seam and the repair becomes a bigger leak than the original problem.
If you see signs of failure, call (361) 209-8857 and we’ll send a background-checked, uniformed technician with a live arrival time you can track. Dylan Pace has spent two decades on every roof type the trade throws at him, from steep-slope shingle to low-slope modified bitumen, and he’s known for straight estimates that don’t balloon after the contract is signed.
FAQs
In San Antonio’s climate, a quality synthetic like CertainTeed DiamondDeck typically lasts 15 – 20 years if the shingles above it are properly maintained, though UV exposure during reroofing and extreme heat cycles can shorten that lifespan. Felt-based RoofRunner ages faster, often showing wear around year 10 – 12. Call (361) 209-8857 for a free estimate so we can inspect what’s currently on your roof.
Yes, if the decking is still structurally sound, we can replace just the underlayment over the affected area without pulling up good plywood. The key is catching it before water has been sitting on the decking long enough to cause rot. If the decking is soft or delaminating, that has to be replaced too. We’ll tell you exactly what’s needed and why before any work starts.
A typical repair with one to four sheets of decking and new underlayment takes one full day, sometimes two if the roofline is steep or the repair wraps around a hip or valley. We’ll give you a clear timeline on the written estimate and send photo updates before and after the work.
We stock DiamondDeck and RoofRunner-compatible materials on our trucks for most standard repairs, plus matching decking in common thicknesses. If your roof needs a specialty CertainTeed product we don’t have on hand, we’ll get it same-week and keep you posted on the timing. Call (361) 209-8857 and we’ll tell you straight what’s needed.
Ready to Get Your CertainTeed Underlayment Fixed?
Every promise we make goes in writing, because a handshake doesn’t keep water out. That means a written price before any work begins, photo updates before and after, and a live arrival time you can track. The 365-Day Done Right Promise covers every repair for a full year. Call (361) 209-8857 to schedule your free estimate, and you’ll know exactly what it costs before you decide.
Written by Dylan Pace, Owner, Crestview Roofing Co San Antonio at Crestview Roofing Co San Antonio, serving San Antonio and nearby areas.