Tamko Underlayment & Deck Repair in Seattle, WA

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

We stock and install Tamko-compatible underlayment and deck repair for Seattle homeowners, with most jobs running $380-$1,200 installed depending on deck exposure and square footage. Same-day service is available when you call before noon, and our trucks carry both Tamko Titan XT underlayment and structural OSB deck panels for the most common profiles. Most Seattle homeowners discover this problem during our wet season: a water spot on the ceiling that grows after every rain, or a section of roof that feels spongy underfoot during gutter cleaning.

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Which Tamko Models This Applies To

Tamko’s underlayment systems pair with their shingle lines in specific ways, and getting the match wrong voids the warranty coverage. Titan XT shingles require Titan XT underlayment for the full limited warranty to transfer; Heritage series can accept either Titan XT or Heritage underlayment, though we typically recommend the heavier Titan XT on Seattle’s lower pitches where ponding is common. The deck repair side is more straightforward: Tamko specifies minimum 7/16″ OSB or 15/32″ plywood, but we’ve found 1/2″ OSB holds up better long-term in our climate.

Here’s how to identify what you’ve got. Check your original paperwork for the shingle series name, or look at the bundle wrappers if you saved any. The underlayment itself will have a Tamko logo and product code printed along the roll edge every few feet. For deck repair, we measure actual thickness with a caliper at the eave, because moisture-swollen deck can read thicker than it is. OEM Tamko underlayment runs about 15% more than quality aftermarket equivalents like Grace Ice & Water Shield or Titanium UDL, but the warranty match matters if you’re keeping records for resale in neighborhoods like Magnolia or Laurelhurst where buyers ask.

Ridgeline Roofing Co. of Seattle is an independent service provider, not affiliated with Tamko. We’re authorized to install their products, and we do - we just don’t work for them.

Signs Your Tamko Underlayment & Deck Repair Is Failing

• Water stains that follow rafter lines. This usually means underlayment has torn or separated at the laps, letting water travel horizontally before it drips. In Seattle’s wind-driven rains, the uphill side of dormers and valleys are the first to go.
• Soft spots when you walk the roof. Deck rot from chronic underlayment failure feels like stepping on a wet sponge. We see this most often on north-facing slopes in Crown Hill and Greenwood where moss holds moisture against the deck for months.
• Shingles lifting or buckling in straight lines. That’s the underlayment wrinkling underneath, often from improper fastening or using a non-breathable product over damp deck. The shingles follow the contour, and wind finishes the job.
• Daylight visible from the attic at seams or fasteners. Underlayment has either blown off or never covered properly. This is common after cheap reroofs where the crew skipped full underlayment to save material.
• Mold or mildew smell in upper rooms after rain. The underlayment is still channeling water, but slowly enough that it’s saturating insulation and framing before it shows as a stain. By the time you smell it, deck damage is usually already present.

Replacement Cost & What’s Included

Tamko underlayment replacement in Seattle typically runs $2.80-$4.50 per square foot for tear-off and reinstall, with deck repair adding $45-$85 per sheet when full replacement is needed. A standard 1,500 square foot roof with localized deck repair usually lands between $380 and $1,200. What drives the range: how much deck is actually damaged (we don’t replace what isn’t rotten), whether we’re working around skylights or steep pitches that slow production, and whether you want the full Titan XT system or a compatible alternative.

Every job includes photo documentation before, during, and after; disposal of old material; and our 90-Day Done Right Promise in writing. The price we quote is the price you pay. We stand behind it - no paperwork, no arguing. Most underlayment and deck repairs finish in a single day, with the crew arriving between 7 and 8 AM.

DIY or Call Us?

There’s an honest line here. A homeowner can safely check the attic for stains, measure soft spots with a screwdriver, and photograph shingle patterns from the ground with a zoom lens. What you cannot safely do is walk a compromised deck, work on a wet or steep roof, or handle full underlayment rolls in wind without proper tie-off. We’ve seen DIY attempts in West Seattle and Rainier Valley where someone stepped through rotted deck or lost their footing reaching for a tool.

The other issue is sequencing: underlayment goes down fast and must be protected immediately. If rain hits exposed deck, you’re replacing more than you started with. Our crews carry tarps rated for 60-mph wind and know the Seattle weather windows. Call (866) 850-9676 and we’ll give you a straight answer on whether this is a job for you or for us.

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