IKO Underlayment & Deck Repair Nationwide

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

IKO underlayment and roof deck repair in San Francisco typically runs $850 to $2,400 installed, depending on how many squares of underlayment need replacing and how much decking has rotted out underneath. We stock IKO-compatible synthetic underlayment, ice and water shield, and CDX plywood on our trucks, so most repairs are done in one visit. The usual way homeowners find us is a leak that tracks down an interior wall or a water stain on the ceiling that shows up weeks after a storm rolls through the Richmond or Sunset District.

Call (831) 228-3330

What surprises most people is how often the deck is the real problem. The IKO underlayment did its job. The plywood underneath gave out first, usually at a valley, a pipe boot, or along an eave where decades of fog and salt air have been working. We see it all the time in the Outer Richmond and the Sunset, where old growth redwood sheathing from the 1920s has turned soft enough to poke a screwdriver through. The underlayment gets replaced because it has to come up to reach the deck, not because it failed on its own. That distinction matters, because it changes what the repair actually costs.

Quick takeaways:

• We replace IKO underlayment and the decking beneath it, matched to your existing roof system.
• Most San Francisco repairs run $850 – $2,400, with a written price before work starts.
• Deck rot and underlayment failure travel together here; replacing one without checking the other is a waste of money.
• Erik Lindgren walks every slope and checks every penetration before quoting a number.

How We Diagnose IKO Problems in San Francisco

Before we quote anything, we want to know what’s actually failing. A stained ceiling tells you water got in. It doesn’t tell you which layer of the roof let it through. In San Francisco houses, especially the older Victorian and Edwardian flats with low-slope sections and multiple roof penetrations, the answer is usually one of three things: torn or improperly lapped underlayment at a transition, rotted decking at a valley or eave, or failed flashing at a penetration that then soaked the deck and the underlayment around it.

Erik grew up in Los Angeles and learned roofing at Los Angeles Trade-Technical College before spending more than two decades on roofs up and down California. He’s been serving San Francisco homeowners long enough to know that the Sunset District’s salt air and old wood sheathing keep an honest roofer on his toes. When he walks a roof, he’s checking every valley, every pipe boot, every chimney cricket, and writing down exactly what he finds before any number gets quoted. A written price before a single shingle moves, that’s just how the job starts.

Which IKO Models This Applies To

IKO underlayment isn’t model-specific the way shingles are. The same brand makes several underlayment lines: Armourbase 40, Armourbase 50, StormShield, GoldShield, and their traditional 15-pound felt. If your roof has IKO shingles over any of these, the underlayment we pull up and replace will match the system, not just the brand name. That said, the shingle series on top tells us a lot about what’s underneath. Cambridge, Dynasty, and Royal Estate all ask for different minimums in the IKO installation guide, and we match what was originally spec’d, not whatever generic roll is cheapest at the supply yard.

Here’s the compatibility gotcha most people miss: IKO’s self-adhered StormShield products and their synthetic Armourbase lines are not interchangeable in the same roof assembly. StormShield is an ice and water shield designed for eave edges, valleys, and around penetrations. Armourbase is a breathable synthetic that goes over the whole deck. If someone previously “fixed” a leak by slapping StormShield over a bad section of Armourbase without addressing the deck below it, the patch traps moisture and accelerates the rot. We see this on San Francisco roofs more than we’d like, usually from previous handyman repairs. Identifying what you have is simple, though. The product name is printed on the underlayment surface itself. We match it, take photos, and document the condition before anything gets torn off.

Signs Your IKO Underlayment & Deck Repair Is Failing

• Ceiling stains that darken after rain: In San Francisco, the pattern isn’t always tied to the last storm. Water moves sideways through old decking before it finds a seam and drips. The stain you see may be six feet from the actual entry point. We trace it from the attic side when access allows.
• Spongy spots or visible sagging on the roof surface: If you can see a dip between rafter lines from the street or a second-story window, the deck below is losing its structure. IKO underlayment won’t bridge a rotting deck. The sag is the deck, not the membrane.
• Granules in the gutters but no bare spots on the shingles: This one puzzles people. Granules wash off where water is moving underneath and backing up, not always where the shingle surface is failing. It’s a signal that the underlayment or deck is holding water somewhere it shouldn’t be.
• Musty or damp attic smells after fog: The fog sits on roofs in the Outer Sunset and Richmond for hours most summer nights. If the underlayment is torn or lapped wrong, that airborne moisture loads the deck with damp air that never quite dries. The smell is the first clue.
• Interior cracks around ceiling fixtures or crown molding: A failing deck flexes. That movement transfers down to drywall seams and finishes. You’ll see it around light cans, ceiling fans, and trim, often mistaken for settling.

How Much Does IKO Underlayment & Deck Repair Cost in San Francisco?

DIY or Call a Roofer?

There are corners of roof work where a careful homeowner can make a real difference, but underlayment and deck repair on an IKO roof is not one of them. Getting to the underlayment means lifting shingles and potentially exposing the deck in a way that leaves your house vulnerable if weather moves in before the repair is closed up. In San Francisco, with the fog rolling through most summer afternoons, that’s a real risk, not a theoretical one. A half-finished DIY underlayment patch is how you get a bigger leak than the one you started with.

What you can safely do is inspect from inside. If you have attic access, shine a flashlight along the underside of the deck in suspect areas. Look for dark staining on the wood, water trails, or visible light through a gap. If you find any of those, call us at (831) 228-3330 and tell us what you’re seeing. You’ll have saved yourself the cost of a diagnostic exploratory opening, and you’ll know before we arrive that the deck is in trouble. But once we know that, this becomes a professional repair. The shingles, the underlayment, the deck, proper nailing patterns, and the sealants all have to work together. When we finish, you’ll have a photo of the clean-up before the crew leaves, shoe covers and drop cloths were part of the job from the first step inside, and the written price you saw at the start matched the written invoice at the end.

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