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Tamko Home Additions & ADU: The San Antonio Owner’s Guide
If you’re planning a home addition or ADU with Tamko materials in San Antonio, you’re looking at $45,000 – $130,000 for a full addition, or $90,000 – $220,000 for an ADU construction project. We stock and install Tamko-compatible roofing, waterproofing, and exterior products as part of these builds, and we match parts to your existing Tamko installs so the new work ties in clean with the old. Most owners call us after discovering their Tamko underlayment or flashing has failed along a roofline or wall intersection, usually after a heavy San Antonio storm exposed a gap they didn’t know was there.
Here’s the thing about Tamko products on additions: the materials are solid, but the failure point is almost never the shingle or the panel itself. It’s the transition. Where the new roof meets the old house, where the ADU wall ties into the driveway slope, where flashing was folded instead of replaced. In Boerne and Stone Oak and Alamo Heights, we see the same pattern: the Tamko product did its job, and the install around it didn’t.
Which Tamko Models This Applies To
Tamko’s lineup for additions and ADUs runs through their Heritage and Elite shingle series, plus their TW-60 and Awaplan underlayments for flat or low-slope sections, which are common on ADU roofs and porch additions throughout San Antonio. If you’re matching an existing Tamko roof, the first thing to check is the shingle’s dimensional profile: Heritage is a laminated architectural shingle with a specific exposure, and Elite runs a slightly different reveal. Mixing them looks wrong from the street, even when the color name matches.
Here’s the compatibility gotcha most homeowners miss: Tamko color lots shift between manufacturing runs. A bundle of Heritage Weathered Wood bought in 2019 won’t be an exact match for the same color name purchased this year. For additions under 300 square feet, that mismatch shows. We tell San Antonio clients to plan for a full re-roof of the existing plane when matching matters, or accept a deliberate contrast line at the transition. On the OEM versus aftermarket question: for Tamko underlayment and flashing, we use Tamko product where it’s still manufactured, and proven equivalents like GAF StormGuard where Tamko’s line has been discontinued. The aftermarket option is not a downgrade when it’s a true ice-and-water shield rated for Texas heat exposure.
Styles & brands we work with
Signs Your Tamko Home Additions & ADU Is Failing
- Water staining at the addition’s roofline intersection. This is the classic failure point: the valley or wall flashing wasn’t stepped correctly, and water wicks under the Tamko shingle edge instead of shedding over it.
- Buckling or lifting on the ADU’s low-slope section. Tamko Awaplan and similar modified bitumen membranes can delaminate from the substrate after years of San Antonio thermal cycling, especially if the original install skipped a primer coat.
- Granule loss in the gutter under the addition’s roof plane. Some granule shed is normal in year one. Heavy, recurring grit in the gutter after year two means the shingle surface is breaking down faster than it should, often from trapped heat in a poorly ventilated addition attic.
- Visible gaps at the wall-to-roof junction on the ADU. If you can see daylight or feel air movement where the ADU wall meets the roof deck, the counterflashing has separated. Water entry is a matter of time, not chance.
- Damp drywall inside the addition after a heavy downpour. By the time interior drywall shows moisture, the Tamko underlayment or flashing has already failed. The interior stain is the last symptom, not the first.
See the difference
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AfterReplacement Cost & What’s Included
For a home addition project involving Tamko roofing, waterproofing, and exterior tie-ins in San Antonio, the full scope runs $45,000 – $130,000 depending on square footage, roofline complexity, and whether you’re adding a second story or building out on slab. For a full ADU construction with Tamko materials throughout the envelope, expect $90,000 – $220,000. If you’re only replacing failing Tamko flashing or underlayment on an existing addition, that’s typically a $400 – $1,800 repair, and it’s the cheapest money you’ll spend compared to tearing out rotted framing later.
What drives the range on larger projects: foundation work, tie-in points to the existing structure, window and door count, and whether the ADU needs separate utility connections. We give you a written line-item price before any work starts, and that’s the number you approve. No change-order games at the end. The workmanship is covered by our 365-Day Done Right Promise: if it’s not done right, we make it right, in writing, on every project.
DIY or Call Us?
You can safely check a few things yourself: look for lifted shingle edges, run your hand along interior drywall for damp spots after rain, and check gutters for heavy granule buildup. That tells you whether you have a problem. It doesn’t tell you where the water is actually getting in.
Flashing and underlayment repair on a roof means working at height, on a slope, with a membrane that has to be sealed right the first time or you’ve made the leak worse. That’s before we talk about San Antonio’s heat turning a roof deck into a griddle by 10 a.m. If you’ve got a failed Tamko transition on your San Antonio addition, call us at (432) 547-6806. We’ll inspect it, show you what we found, and put the fix in writing before we touch a single shingle.
FAQs
Tamko Heritage shingles typically last 20 – 25 years in San Antonio’s climate, but the underlayment and flashing around transitions often fail in year 10 – 15 if they weren’t installed with proper overlaps and sealant. Call (432) 547-6806 for an inspection if your addition is over a decade old and you haven’t had the roof transitions checked.
It depends on the age and condition; small sections of separated counterflashing can sometimes be re-secured, but torn or corroded step flashing should be replaced to stop the leak properly. Call (432) 547-6806 and we’ll tell you honestly which path makes sense for your roof.
A full ADU construction with Tamko materials runs 4 – 8 months from permit to walkthrough in San Antonio, while a flashing or underlayment repair on an existing addition is usually done in one day. Call (432) 547-6806 for a timeline specific to your project scope.
Yes, we keep Tamko flashing, underlayment, and common shingle colors stocked for San Antonio jobs, and we order specific color lots when matching an existing roof matters. Call (432) 547-6806 and we’ll confirm what we have before we schedule the visit.
We’re an independent San Antonio contractor, not affiliated with Tamko, but we’ve been installing and repairing their products on additions and ADUs across the metro for years. Luca Romano still does a final walkthrough on every job himself. The craft comes first. Everything else follows. If you’re building an addition or ADU with Tamko materials in San Antonio, call (432) 547-6806 for a free estimate, a written price, and a timeline you can actually plan around.
Written by Luca Romano, Owner, Sawyer Remodel San Antonio at Sawyer Remodel San Antonio, serving San Antonio and nearby areas.
