Tamko Underlayment & Deck Repair Nationwide

Tamko Underlayment & Deck Repair: The Fresno Owner’s Guide

We stock and install Tamko-compatible underlayment and deck repair materials across Fresno, with most residential repairs running between $850 and $2,400 depending on how much decking has rotted and how many squares of underlayment need replacing. Most jobs are finished in one day, and we carry Tamko’s TW Metal and synthetic underlayment lines on our trucks so we’re not running back and forth to the supply house while your roof is open. The way Fresno homeowners usually discover the problem: a leak stain on the ceiling after a heavy winter rain, or a roofer doing an inspection who finds soft decking under the shingles near a valley or pipe boot.

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Here’s the part nobody tells you: the underlayment is the roof’s real waterproofing layer. Shingles shed water, but underlayment is what stops the water that gets past the shingles. When that layer dries out and cracks under a Fresno summer of 105-degree days, every future rainstorm becomes a slow drip into your attic. And if the decking beneath it has been wet for long enough, you’re not just replacing felt, you’re cutting out plywood. That’s the repair we do most often on Tamko roofs in Fresno: rotted deck sections replaced, new underlayment floated over the repair, and the whole area re-shingled to match.

Which Tamko Models This Applies To

The underlayment and deck repair process is the same whether you have Tamko Heritage laminated shingles, Elite Glass-Seal three-tabs, or the MetalWorks steel line. What changes is the accessory layer underneath. Tamko specifies two main underlayment products: TW Metal, a mechanically fastened synthetic rated for high-heat metal roof assemblies, and Tamko’s standard synthetic underlayment used under asphalt shingle systems. If you’ve got a MetalWorks roof in Fresno, you need a high-temperature underlayment that won’t melt or adhere to the metal panels when that steel hits 140 degrees in July. That’s a gotcha we see a lot: someone installs a generic felt under a metal Tamko roof, and within two summers the felt has baked brittle and started wicking moisture.

For decking, Tamko’s warranty documentation requires a minimum of 3/8-inch exterior-grade plywood or OSB, properly fastened, with no gaps over 1/8 inch. In practice, half the Fresno homes we open up have 1/2-inch CDX from the 1980s or 1990s that’s delaminated at the edges. We replace with 1/2-inch or 5/8-inch exterior-grade CDX, which is the same thickness range Tamko’s installation specs call for. One OEM-vs-aftermarket note: Tamko’s branded synthetic underlayment is well-made, but we’ve also installed GAF FeltBuster and Owens Corning ProArmor in Tamko roof systems with no compatibility issues. The key is that it’s a synthetic rated for the heat, not that it says Tamko on the wrapper.

Signs Your Tamko Underlayment & Deck Repair Is Failing

• Water stains on ceilings or walls after Fresno rainstorms. Stained drywall below an attic space means water has already saturated the underlayment and is pooling somewhere above. By the time you see it inside, the decking below has usually been wet for weeks or months.
• Soft or spongy spots when walking the roof. Plywood decking rots from the underside first, where leaks sit against the wood. If a section of the roof feels bouncy underfoot, the deck has lost its structural rating and needs replacement, not re-felting.
• Granule buildup in gutters, especially after summer heat waves. Tamko shingles shed granules as they age, but excessive granule loss often means the underlayment below has been getting hot and dry, accelerating shingle deterioration from beneath.
• Visible felt or synthetic paper sagging in the attic. If you can see underlayment drooping between the rafters, the fasteners have failed or the material has stretched from heat and moisture. This is a clear sign the waterproofing layer is no longer doing its job.
• Musty attic odor in summer. Trapped moisture in insulation and decking creates a noticeable smell when Fresno temps climb. That odor usually means ongoing, small-scale leakage rather than a single dramatic storm event.

Replacement Cost & What’s Included

In Fresno, Tamko underlayment replacement alone typically runs $350 to $600 per square (100 square feet) when the decking is sound. Add rotted deck repair and you’re looking at $3.50 to $5.50 per square foot for the affected sections, including cutting out the bad plywood, refastening, and installing new decking. A typical repair involving one valley or pipe boot with two to three sheets of rotted decking lands between $850 and $1,800. Full underlayment replacement on a larger roof runs proportionally higher.

You see a written price before any work starts, always. The number includes materials, labor, and disposal. It doesn’t change once work begins unless we open the roof and find something nobody could have seen from the outside, and even then, we stop and explain it before touching anything else. Every repair is covered by our 365-Day Done Right Promise: if it’s not right, we make it right.

DIY or Call Us?

There are a few things worth checking yourself from the attic or the ground: daylight showing through the roof boards, damp insulation, sagging underlayment. That’s useful information to have before you call. But actually replacing underlayment means stripping shingles, pulling fasteners, walking the roof surface, and working at height. A fall from a Fresno single-story roof is still a fall. And more importantly, if you nail the new underlayment improperly or miss a seam, you’ve created a leak that will rot your decking all over again, silently, until the next rain.

We handle the whole thing for you, and we do it the way Erik Lindgren has always run jobs in Fresno: shoe covers at the door, drop cloths through the hallway, all debris cleared and photographed before we leave. If your dog needs to stay inside during the repair, we coordinate the door schedule so you’re not wrangling animals mid-project. Call (559) 785-9461 and tell us what you’re seeing on the ceiling, and we’ll tell you exactly what’s happening six feet above it. Estimates are free.

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