IKO Underlayment & Deck Repair Nationwide

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

IKO underlayment and deck repair in San Jose typically runs $1,200 to $3,800 installed, depending on how much decking has failed and which IKO underlayment line goes back down. We stock IKO-compatible underlayment and decking materials on our trucks and can usually start the repair within a few days of your estimate. Most San Jose homeowners discover the problem the hard way: a ceiling stain after winter rain, granules in the gutter after a windstorm, or a soft spot felt underfoot during a roof inspection.

Call (669) 238-2101

The underlying issue is rarely just the shingle you can see. Water gets past the shingle, saturates the underlayment, and then rots the decking below. By the time you notice it inside the house, the deck has usually been compromised for months. That’s the repair we do most often in San Jose: cut out the rotted deck section, replace it, lay fresh IKO underlayment, and re-shingle the area so it sheds water the way it should.

Which IKO Models This Applies To

IKO makes three underlayment lines that show up routinely on San Jose roofs: GoldSeal (their mid-grade self-adhering ice and water shield), StormShield (their premium high-temp self-adhered option), and RoofGard (a synthetic felt replacement, often used as a full-field underlayment). If your roof was installed with IKO shingles, the underlayment is most likely one of these three, but we’ve also pulled off old #15 felt on IKO re-roofs from the early 2000s.

Identifying what you have is straightforward: the underlayment surface is printed with the product name every few feet, and the roll end sometimes carries a width marking. GoldSeal and StormShield are peel-and-stick products that come in 36-inch rolls; RoofGard is a lighter synthetic, usually 48 inches wide. The compatibility gotcha with IKO self-adhered membranes is temperature: StormShield carries a higher-temperature rating for San Jose’s summer roof surface heat, which regularly exceeds 140 degrees on south-facing slopes in Willow Glen or Almaden Valley. We recommend StormShield when the deck is being fully replaced on a steep or dark-shingled roof plane, and GoldSeal for standard eave and valley coverage. As for OEM versus aftermarket: IKO private-labels their membranes, and quality equivalents from GAF, CertainTeed, and Owens Corning perform comparably when spec-matched. We’ll give you the options in writing with the price difference spelled out before any work starts.

Signs Your IKO Underlayment & Deck Repair Is Failing

• Ceiling stains or drips in upstairs rooms. Water has already passed through the shingles, underlayment, and decking. The leak is active and the deck is wet, which means rot is already underway.
• Soft, spongy spots when walking the roof. This is delaminated decking, usually OSB or plywood that has absorbed water repeatedly and lost structural strength. It won’t recover; it gets cut out.
• Wrinkled or lifted underlayment visible at the eaves or in the attic. Underlayment wrinkles when it’s exposed to moisture cycles or was installed over a damp deck. Once it’s wrinkled, it channels water instead of repelling it.
• Musty attic smell or damp insulation near the eaves. Water is entering at the eave line or a valley and following the decking inward. By the time you smell it, the deck has been wet for a while.
• Granule buildup in gutters after storms. A few granules are normal. A visible layer of granules after each rain means the shingle surface is failing and water is reaching the underlayment sooner than IKO designed for.

Replacement Cost & What’s Included

Here’s what we price in San Jose, based on the deck condition and roof access:

• Small deck patch and underlayment repair (one to three sheets of decking): $1,200 to $2,200
• Moderate deck replacement (up to 200 square feet): $2,200 to $3,800
• Full underlayment replacement on a roof plane with new IKO shingles: $3,800 to $8,500, depending on slope, height, and deck condition

The range is driven by how much decking has actually rotted, which roof plane is involved, and whether the existing underlayment can be kept in the unaffected areas. Every estimate from us includes materials, labor, haul-off, and the written price in your hand before any work begins. The price does not move at the door. And every repair carries the 365-Day Done Right Promise: in writing, for one full year, we come back for free if the repair fails.

DIY or Call Us?

You can safely check two things from the ground: look for lifted or missing shingles after a storm, and check gutters for unusual granule buildup. That’s the extent of it. Walking a roof without proper fall protection is how homeowners get hurt most often in this trade, and probing decking for soft spots without knowing how to read the roof means you may miss the real damage or, worse, punch through a rotten section. IKO underlayment installation is only as good as the deck underneath it. If the deck isn’t flat and dry, the membrane won’t seal, and you’ll pay twice.

Call (669) 238-2101 and describe what you’re seeing. Tell me what you’re seeing and I’ll tell you what it actually means. We’ll schedule an estimate, get the price on paper, and take it from there.

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