Tamko Underlayment & Deck Repair Nationwide

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

We stock and install Tamko underlayment and decking repair materials throughout San Jose, with most underlayment replacements running between $400 and $1,200 and decking repairs typically landing between $300 and $800 depending on how much sheathing has to come out. If your roof is leaking, staining, or you can see daylight through the attic, we can usually get eyes on it within 48 hours. The way most homeowners discover this problem is not glamorous: a water stain on the ceiling after a heavy rain, granules in the gutter, or an inspector flagging soft decking during a roof replacement quote.

Call (669) 238-2101

This is not a part you should guess at. Underlayment is the waterproofing layer between your decking and your shingles. When it fails, everything above it fails faster. And decking, which is the plywood or OSB under the underlayment, is the structural floor of your roof system. If that’s rotten, no shingle on earth will save you.

Which Tamko Models This Applies To

Tamko makes underlayment products that work across their shingle lines, including Heritage, Titan XT, and Elite Glass-Seal. The underlayment itself splits into three main categories: synthetic underlayment like Tamko’s Apex, traditional felt (Tamko’s 15 and 30 pound organic felts), and self-adhered membrane products like their Moisture Guard line used for leak-prone areas like valleys, eaves, and penetrations.

Here’s the compatibility gotcha most homeowners don’t know: Tamko’s warranty language for certain shingle systems requires specific underlayment specifications to keep the system warranty intact. You cannot swap in whatever felt is on sale and expect the manufacturer to stand behind the roof. We verify the spec against your exact Tamko shingle line before we quote. For most San Jose homes built in the last 20 years, you’re looking at a synthetic underlayment replacement, but older homes around Willow Glen and The Alameda still have organic felt or even skip-sheathing with no solid deck at all, which changes the repair entirely.

We also stock compatible alternatives from GAF, Owens Corning, and CertainTeed when a homeowner wants a specific performance profile or price point. The decision comes down to what’s already under your shingles and what your warranty requires.

Signs Your Tamko Underlayment & Deck Repair Is Failing

Here’s what we see most often in San Jose when underlayment or decking has gone bad:

• Water stains on ceilings or walls after rain. This means water has already gotten past the underlayment and through the decking. The roof leak you see inside is rarely where the roof leak is outside. Water travels along rafters and decking seams before it drops, so the stain is downstream from the actual entry point.
• Soft spots or spongy feel when walking the roof. This is rotted decking. In San Jose’s wet winters and hot dry summers, decking swells and contracts, and once moisture gets trapped between felt and wood, rot sets in fast. A soft deck is a structural problem, not a cosmetic one.
• Granules collecting in gutters or at downspout bases. Shingle granule loss accelerates when the underlayment beneath is failing because the shingles move more and rub. If you’re seeing granules in the gutter every month, the problem may not be the shingles at all.
• Visible daylight or sagging felt in the attic. Get up in the attic during the day with the lights off and look for pinholes of light or sagging material between the rafters. Both mean the underlayment has torn, slipped, or was never installed correctly in the first place.
• Moldy or musty attic smell in the dry season. Underlayment that traps moisture against the decking feeds mold even when it’s not actively raining. San Jose’s summer heat bakes the trapped moisture into the wood, and the smell comes through the ceiling.

Replacement Cost & What’s Included

Here’s what we tell San Jose homeowners before any work starts, because you should know the number before you decide anything.

What drives the range: how much decking has to come out, whether we’re working around a steep pitch or multiple stories, and whether your Tamko shingle warranty requires a specific underlayment spec. The price we quote is the price on the invoice. No door-knock adjustment, no “we found something else” add-on. If we find hidden damage once the shingles come off, we stop, show you, and put a new number in writing before we touch it.

Every repair carries the 365-Day Done Right Promise: in writing, for one full year, and we come back at no charge if it fails. That’s the Garrison Standard we operate under, and it’s the same on every job whether it’s a small patch or a full re-roof.

DIY or Call Us?

You can safely inspect your attic for light penetration, check for granule buildup in gutters, and note any ceiling stains. Those checks cost nothing and they tell you a lot. What you should not do is strip shingles and replace underlayment or decking yourself. Walking a San Jose roof with a tear-off bar means working at height on a surface that’s already compromised. One wrong step through soft decking and you’re in the attic faster than you meant to be. Underlayment also has to be lapped correctly, fastened to manufacturer spec, and sealed at every penetration or the repair fails within months.

Travis Oakley learned this trade at Los Angeles Trade-Technical College and has been on enough San Jose roofs to know what corners look like from the inside out. His rule is simple: “Tell me what you’re seeing and I’ll tell you what it actually means.” If you’ve got staining, granules, or a soft spot, call (669) 238-2101. We’ll inspect it, give you a written price, and if it turns out to be less than you feared, that’s what you’ll pay.

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