Tamko Underlayment & Deck Repair Nationwide

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

If your Tamko roof is leaking, buckling, or the decking feels soft underfoot, the underlayment has almost certainly failed. In San Jose, we replace Tamko-compatible underlayment and damaged deck sections for $650 to $1,900 on most homes, depending on how much decking has rotted and how steep your roof is. The typical repair takes one day, and we stock Tamko TW Metal & Tile underlayment and its common equivalents on our trucks so we’re not making you wait on a supplier run.

Call (669) 274-0078

What we usually hear from homeowners sounds like this: a dark stain appears on the ceiling after the first real rain in November. Maybe it’s under a valley, or along a roof-to-wall transition. Then someone goes into the attic with a flashlight and finds a patch of plywood that’s turned the color of wet cardboard. That’s where the underlayment tore, separated at a seam, or wasn’t lapped correctly when the original roof went on. By the time you see the stain inside, the deck has been soaking for a while.

Here’s the part most people don’t know: underlayment isn’t the roof. It’s the waterproof membrane that sits between the deck (the plywood or OSB sheets) and the shingles or tiles you see from the street. When it fails, water gets to the deck. When the deck rots, everything above it loses its anchor points. Fixing the underlayment without checking the deck is like putting a new tire on a cracked rim. We always inspect both.

Which Tamko Models This Applies To

Tamko makes two underlayments we see most often in San Jose: TW Metal & Tile, which is a fiberglass-reinforced, SBS-modified base sheet, and Apex Self-Adhered, used mostly for ice-and-water shield applications at eaves and valleys. TW Metal & Tile is the workhorse here, because the South Bay has a lot of older concrete and clay tile roofs from the 1960s through 1990s, and that’s exactly what this product was designed for. If your home is in Willow Glen, Almaden Valley, or the Rose Garden with an original tile roof, odds are your underlayment was either that product or an equivalent from the era.

The compatibility gotcha we run into constantly: TW Metal & Tile is a 48-square-foot roll that installs as a single layer under tile. If a previous contractor installed just one layer of a standard 30-pound felt instead of the reinforced Tamko product, that’s why the roof failed inside 15 years. Tile is heavy, and it moves with heat cycling. Standard felt tears at the nail line over time. The reinforced fiberglass mat in the Tamko product resists that tearing. When we’re matching materials, we measure the exposed roll at an eave or rake edge if you have a torn section, and we look at the pattern of the fiberglass grid on the sheet’s surface. It’s identifiable if you know what you’re looking at.

One honest note: Tilehurst Roofing San Jose is an independent roofing contractor. We install and repair Tamko-brand products, and we also stock equivalents from GAF, Owens Corning, and CertainTeed, but we’re not a Tamko factory branch or a Tamko-owned service. If your original underlayment was a Tamko product, we’ll match it. If the home had a different brand under there, we’ll match that, because continuity matters more than brand loyalty when it comes to keeping water out.

Signs Your Tamko Underlayment & Deck Repair Is Failing

• Ceiling stains that darken after rain, then lighten in summer. This is the classic San Jose signature. The underlayment tears or separates, water follows a rafter or a seam line, and the stain map tracks every wet season. The deck above that stain is likely spongy by now.
• Soft or sagging spots in the roof plane when viewed from the street. OSB and plywood both lose structural strength when they’ve been wet for more than a season. If you can see a visible dip between rafters from your curb, that’s deck failure, not just an underlayment problem.
• Missing, broken, or shifted tiles that expose the black sheet below. Once UV light hits underlayment directly for a summer or two, it dries out and cracks. The crack lines let water straight through. That first cracked section is also the first place it fails.
• Granule-filled dust washed into your gutters in the spring. Tamko underlayment has a mineral surface on one side, and when it’s failing, that surface sheds. It’s not as obvious as shingle granules, but it’s a real early-warning sign if you’re looking for it.
• A damp smell in the attic after any rain, even without a visible stain. The underlayment can be performing at maybe 60 percent, letting moisture through but not enough to produce a ceiling stain yet. The attic air carries that damp, musty note. That’s usually when we find seams peeling and nail heads rusted through.

Replacement Cost & What’s Included

For a Tamko underlayment patch with limited deck replacement in San Jose, budget $650 to $1,100. If the deck has rotted across a whole slope and we’re pulling and resetting tile over two or three hundred square feet, you’re looking at $1,400 to $1,900. The price moves on three things: how much plywood we’re replacing, how steep your roof is, and how much tile has to come off and go back on.

What you get for that price, in writing: the square footage of underlayment replaced, the number of deck sheets replaced, the brand of each material, and the labor to remove and reset your existing tile. You’ll also get a written guarantee on the repair before the crew leaves the driveway, not mailed to you six weeks later. If that repair fails inside a year, we return and fix it at no cost under the 365-Day Done Right Promise.

Call Greg and the crew at (669) 274-0078 and we’ll put an exact number in your hands before a single tile comes off.

DIY or Call Us?

You can safely inspect your own roof from the ground or a ladder, and you can check the attic for wet decking with a flashlight. What you cannot safely do is work on a tile roof while carrying sheets of plywood and rolls of underlayment. That’s steep-pitch work in most of San Jose, and once you start pulling tile, you need to know how the old clay interlocks and where the next rain will find you if you don’t get the laps and fasteners right.

We see DIY repair attempts fail most often at the seams, because underlayment has to lap in a specific direction and order so water flows over, not under, each joint. Get that backwards and your repair leaks worse than the original damage. If you call us, the truck shows up with the Tamko product plus decking, fasteners, and correct sealant on board. If you’d rather talk it through first, call (669) 274-0078 and tell us what you’re seeing. Straight answer, no guesswork.

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