Tamko Underlayment & Deck Repair Nationwide

Tamko Underlayment & Deck Repair: The Los Angeles Owner’s Guide

If your Tamko shingles are lifting, leaking, or failing well before their rated lifespan, the problem is rarely the shingle itself. In Los Angeles, we find the underlayment or the roof deck underneath has failed first. We stock Tamko-compatible underlayment and deck repair materials on our trucks, and most underlayment repair or deck replacement in Los Angeles runs between $450 and $1,800 depending on how much decking needs to come out. Here’s how the failure usually shows up: you’ll see water staining on a ceiling after heavy rain, or shingles that look wavy and uneven from the ground, or you’ll catch a whiff of mildew in the attic on a humid Santa Ana day. That’s the underlayment giving out, not the shingles. And if the decking below has gone soft or rotted, the fix is a partial deck replacement before new underlayment goes down.

Call (213) 521-8272

Key Takeaways

• Tamko underlayment and deck failure is the #1 cause of premature shingle failure we see in Los Angeles.
• Typical installed repair cost in LA: $450 – $1,800 depending on deck condition and square footage.
• We write the price before any work starts, and every repair carries a 365-day written guarantee.
• You’ll know the technician’s name and see their photo before they arrive at your door.

Which Tamko Models This Applies To

Tamko makes two underlayment lines that show up on Los Angeles roofs: Tamko TW Underlayment (fiberglass-reinforced, often used under their Heritage and Elite shingle lines) and Tamko Moisture Guard (a peel-and-stick underlayment for eaves, valleys, and low-slope sections). The deck repair side applies to any Tamko shingle system where the plywood or OSB decking beneath has absorbed water, warped, or delaminated. That includes Tamko Heritage, Heritage Premium, Elite Glass-Seal, and Lamarite slate and shake composites.

The gotcha we see in Los Angeles is this: Tamko TW underlayment has a mineral surface, and if it’s installed over an older layer of felt that’s still holding moisture, it can trap that moisture against the deck and rot it from the underside. You won’t see that from the street. The only way to catch it is an attic inspection or a deck probe from above. When it comes to replacement, Tamko’s own underlayment is what we recommend under Tamko shingles for warranty consistency, but for the deck itself, a quality CDX plywood or OSB rated for roof sheathing works fine. The key spec is thickness: most Los Angeles homes built before the 1980s have 1/2″ decking, and most modern code wants at least 7/16″ OSB or 1/2″ plywood at 24″ on-center spacing. If your decking is 3/8″, that’s a replacement candidate regardless of condition. Mercer Roofing Co is an independent service provider, not affiliated with Tamko, but we install and repair Tamko systems and stock compatible underlayment on our trucks.

Signs Your Tamko Underlayment & Deck Repair Is Failing

• Water stains on ceilings or walls after rain. This is the classic sign underlayment has a breach. The shingles can look perfect from outside while water tracks along the underlayment seam and finds a nail hole to drip through. In Los Angeles, this often shows up after February’s atmospheric river storms rather than summer drizzle.
• Shingles that look wavy, lifted, or “buckled” at the edges. That’s not a shingle defect. Moisture has reached the deck, the deck has swelled, and the shingle can’t lie flat anymore. Re-nailing won’t fix it; the deck underlayment layer has to be addressed.
• Granules in the gutter paired with soft spots underfoot. Granule loss means the shingle has aged past its protective point. When you combine that with a deck that feels spongy or gives underfoot, you have both a shingle problem and a deck problem. Tamko’s mineral-surface underlayment can actually hide deck softening longer than paper felt, because the mineral granules shed water so effectively, water sits on top until it finds a puncture.
• Mildew or musty smell in the attic, especially after heat waves. Los Angeles attics get brutally hot in August and September. If underlayment is failing, trapped moisture cooks in that heat and you’ll smell it. It’s worse in older homes in Echo Park and Highland Park where original decking from the 1950s and ’60s is still in service.
• Visible deck rot at the eaves or in valleys. Peel back the drip edge or look up from a ladder at the eave line. If you see dark, crumbling, or flaking wood, the deck has been wet for a long time. Tamko Moisture Guard failing at the eaves is the most common culprit in Los Angeles, because that’s where water backs up when gutters clog with jacaranda leaves in spring.

Replacement Cost & What’s Included

Here’s what we tell Los Angeles homeowners before anyone climbs a ladder:

The range depends on three things: how much decking has to come out, how steep or cut up your roof is, and whether we’re matching existing Tamko shingles or replacing a section. You’ll get the parts and labor broken out in writing before we touch anything. Every repair carries a 365-day written guarantee, and if the repair fails within that year, we come back and fix it on our dime. That’s not a promise we hedge on. Call (213) 521-8272 for a free estimate with a written price before any work starts.

DIY or Call Us?

Here’s the honest split. You can absolutely check for underlayment and deck problems from the ground or attic yourself. Look for water stains, feel for soft decking in the attic, and check your gutters for granules. That’s safe, useful information. What we don’t recommend: walking a two-story Los Angeles roof with a hammer and a roll of underlayment, especially after rain when the surface is slick. It’s not about the spring tension like a garage door or the voltage like a panel; this is about the height and the unpredictability of what’s underfoot. Roof decks in Los Angeles get soft from hidden leaks, and a soft deck is a fall waiting to happen. If you want a professional to inspect, quote, and repair Tamko underlayment and deck issues, call (213) 521-8272. You’ll know exactly who’s coming to your door before they knock, because we send the name and photo first.

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