Tamko Underlayment & Deck Repair Nationwide

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

If your Tamko roof is leaking, buckling, or showing water stains, the problem usually isn’t the shingles – it’s what’s underneath them. Underlayment and decking fail first, and when they do, water gets into places it should never go. Mercer Roofing Co San Antonio stocks Tamko-compatible underlayment and decking materials, and most repairs run between $450 and $1,800 installed depending on how much decking needs replacing and how many layers of old material we have to pull up. We can typically have a crew out within a few days to diagnose it, and the diagnosis is free.

Call (254) 276-4369

Here’s the thing most San Antonio homeowners don’t realize: your Tamko shingles can look fine from the ground while the decking underneath is quietly rotting. You discover it during a repair, or worse – when a leak finally shows up on your ceiling. By then, a $600 deck repair has turned into a $2,400 job that includes drywall and insulation. So if you suspect underlayment or deck failure, the smartest move is to have us look before it spreads.

Key Takeaways:

• Tamko underlayment and decking typically last 15 – 20 years in San Antonio’s heat-and-humidity cycle, but failed flashing or trapped moisture can cut that in half.
• Installed repair costs in San Antonio usually run $450 – $1,800 depending on decking condition and square footage.
• We stock Tamko-compatible synthetic underlayment and OSB/plywood decking on our trucks, so most repairs are one trip.
• Every repair comes with a written guarantee: 365 days, free second visit if it fails.

Which Tamko Models This Applies To

This page covers underlayment and decking across Tamko’s shingle lines: Heritage, Elite Glass-Seal, Titan XT, and MetalWorks. The underlayment and decking are the layers beneath whatever Tamko shingle you have, so the compatibility question isn’t really about your shingle model – it’s about what’s already on your roof deck and what your Tamko system was originally installed with.

Tamko ships two main underlayment types: their TW Metal and Tile Underlayment (a peel-and-stick modified bitumen product used in high-heat, high-slope applications) and their Synthetic Underlayment line (a polypropylene sheet that replaces old-school 15-pound and 30-pound felt). If your roof originally used peel-and-stick, you don’t want to swap in anything thinner – that’s a compatibility gotcha that causes leaks down the line, especially in San Antonio where summer attic temperatures top 140°F and cheap underlayment can literally melt and re-seal itself improperly. We match the original spec, not whatever’s cheapest.

Decking is simpler: it’s either OSB, CDX plywood, or (on older San Antonio homes, particularly in Alamo Heights and Terrell Hills) tongue-and-groove boards. Measure the thickness – 7/16″, 15/32″, or 1/2″ are the common OSB specs; 1/2″, 5/8″, or 3/4″ for plywood. We inspect for sag between rafters, soft spots, and fastener pull-through before deciding whether a section gets replaced or the whole deck needs re-sheeting.

One more thing worth stating plainly: Mercer Roofing Co San Antonio is an independent roofing contractor. We install and repair Tamko products but we’re not affiliated with Tamko Building Products. We stock genuine Tamko underlayment and Tamko-compatible OEM-equivalent underlayment for repair work, and we’ll tell you which one we’re quoting and why.

Signs Your Tamko Underlayment & Deck Repair Is Failing

• Water stains on ceilings or attic sheathing. This is the one nobody misses. By the time it shows up indoors, the underlayment has already been compromised long enough for water to soak the decking. The stain is the last symptom, not the first.
• Shingles looking “wavy” or uneven from the curb. That’s usually the decking swelling or warping underneath. When OSB absorbs moisture, it expands, and the shingles above telegraph that movement as visible rippling.
• Granular patches of missing shingle surface with exposed felt or black material. Once underlayment is exposed to direct sunlight for even a few San Antonio summers, it starts to dry-rot and delaminate. Peel-and-stick underlayment especially degrades fast under UV exposure if shingles tear away.
• A soft, spongy feel when walking on the roof. If our technician’s foot sinks at all, the decking is shot. This is a safety issue for anyone on the roof, and it means water has been sitting in the wood fibers for a long time.
• Mold or mildew smell in the attic after heavy rain. That’s moisture trapped between the decking and the underlayment. In San Antonio’s humidity, that trapped moisture breeds mold fast, and the only real fix is cutting out the affected deck section and drying the cavity before re-sheeting.

Replacement Cost & What’s Included

Here’s what our San Antonio customers typically pay for Tamko underlayment and deck repair, installed:

Every one of those prices is a written, line-item quote before we start. No change orders, no “we found more damage” surprise upcharges. If we do find additional rot once we peel the shingles back – and we often do – we’ll photograph it, show you on the spot, and give you a new written price before touching it. You approve everything.

The price includes the materials, labor, old-material disposal, and our 365-Day Done Right Promise: if the repair fails within a year, we come back and make it right for free. That’s not a verbal promise. It’s on paper, on every invoice.

DIY or Call Us?

Here’s the honest split. You can safely check for warning signs from ground level: look for missing shingles, sagging rooflines, and attic stains. You can even pull back a loose shingle corner and shine a flashlight at what’s underneath – if you see black streaks, crumbling felt, or dark water rings on the wood, the underlayment or decking is done.

What you shouldn’t do is open up a San Antonio roof in July and try to patch it yourself. A roof deck in summer is 150°F or hotter. Underlayment removal requires the right peel-stick technique or the new layer won’t bond. And walking on soft decking without knowing where the rafters are is how people fall through. We’ve repaired plenty of DIY patches where the “fix” trapped moisture under a new layer and made the rot worse within a year. If you’re not sure, call us at (254) 276-4369 and we’ll take a look. A diagnosis costs you nothing.

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