Tamko Home Additions & ADU Nationwide

Tamko Home Additions & ADU: The San Antonio Owner’s Guide

Elmstead Remodeling San Antonio installs and supports Tamko-compatible home additions and ADU projects across San Antonio, with most accessory dwelling units landing between $90,000 and $220,000 depending on size, foundation work, and finish level. We’re an independent contractor, not affiliated with the Tamko corporation, but we work with Tamko roofing and weatherproofing products regularly on additions because their materials hold up in South Texas heat and sudden downpours better than most. Most owners call us when a Tamko underlayment or flashing detail on an existing addition shows signs of failure after a decade of San Antonio sun, or when a new ADU plan needs material selection that won’t warp or peel within the first five years.

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Which Tamko Models This Applies To

Tamko’s product line relevant to home additions and ADUs in San Antonio centers on their Heritage and Elite shingle series, their metal roofing panels used on shed-roof ADUs, and the moisture barrier and underlayment systems that protect those additions at the eaves and valleys. The compatibility gotcha most homeowners hit is that Tamko’s self-adhered ice-and-water membrane needs a clean, dry substrate at install, and in San Antonio’s humid summers, roll adhesion fails when crews rush the job before morning dew fully evaporates. We check the product labels on existing Tamko materials before quoting any addition repair: the shingle series stamp and the underlayment roll code tell us whether it’s an original install from ten-plus years ago or a newer spec. For new ADU construction, we lean on Tamko’s engineered wood and composite trim when the plan calls for painted fascia and window surrounds, because their factory primer handles Texas UV better than raw wood trim.

Signs Your Tamko Home Additions & ADU Is Failing

• Lifting or curling shingle edges along the addition’s roofline: Tamko’s asphalt shingles last 15 to 25 years, but San Antonio heat cycles bake the asphalt and cause the edges to curl first at the west-facing slope. Underlying cause is usually lost granule adhesion, not the shingle itself failing.
• Dark streaks or moisture staining where the addition roof meets the main house: That’s the valley flashing or the underlayment failing, and with Tamko systems, the weak point is almost always the transition seam, not the material mid-panel.
• Soft spots on the ADU subfloor near the exterior wall: Water is coming in around the door threshold or a window and sitting on the Tamko moisture barrier instead of draining away from the sill.
• Mold or mildew smell inside the addition just after rain: In San Antonio’s clay soils, additions shift slightly, and a shifted wall plane opens a gap that the original Tamko flashing can no longer bridge.
• Peeling paint or warped board on the addition’s exterior trim: If original trim wasn’t Tamko’s pre-primed composite, it’s likely wood soaking up humidity and failing ahead of the roofing materials around it.

Replacement Cost & What’s Included

For a home addition in San Antonio, expect $45,000 to $130,000 for a full build-out with Tamko roofing and weatherproofing materials, foundation, framing, and finishes. A dedicated ADU runs $90,000 to $220,000 because it adds utility connections, a separate HVAC system, and city permitting. Parts-only repair on a failed Tamko component, like replacing a damaged underlayment section or re-flashing a valley, typically falls within our broader project minimums and is quoted as a written line item before work starts. What drives the range: square footage, whether the addition is built over a slab or pier-and-beam, the condition of the existing framing, and whether the San Antonio Development Services permit review requires structural upgrades. We write the price down before a single tool leaves the truck, and the 365-Day Done Right Promise covers every completed addition; if something’s not right after move-in, we make it right.

DIY or Call Us?

You can safely do a visual check yourself: look for curling shingle edges, gaps at the flashing where the addition roofline meets the main house, and any dark staining on interior ceilings after a heavy San Antonio rain. What you shouldn’t do is get on an addition roof or an ADU roof without fall protection, and you shouldn’t peel back Tamko underlayment to inspect the decking underneath because you’ll compromise the water barrier and create a new leak. If you’re planning a new addition or an ADU, the materials decision is where DIY really goes wrong: cheap underlayment on a South Texas roof means a full tear-off years before a Tamko-spec install would even need repairs. Call us at (432) 233-0976 and we’ll walk the existing structure with you, name the failing part, and put a written price in your hand.