IKO Underlayment & Deck Repair Nationwide

IKO Underlayment & Deck Repair: The Los Angeles Owner’s Guide

IKO underlayment and deck repair in Los Angeles typically runs $450 to $1,800 installed, depending on how much decking has rotted and which IKO underlayment line your roof was built with. We stock IKO-compatible underlayment rolls on our trucks and can match decking thickness to your existing sheathing the same day we inspect. Most Los Angeles homeowners discover the problem after a leak shows up on the ceiling, or when a roofer doing a patch pulls back shingles and finds the decking underneath has gone soft from years of trapped moisture.

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The underlayment is the water-shedding layer between your roof deck and the shingles. When it fails, water sits against the plywood or OSB decking and the rot starts. We see it most often in older IKO installations across the San Fernando Valley, Pasadena, and the Westside, where original felt underlayment from the 1990s and early 2000s has simply outlived its useful life. Travis Oakley has pulled enough of these apart to know what failed first, and it’s rarely the shingles.

Which IKO Models This Applies To

This repair path applies to any Los Angeles roof built with IKO shingles or IKO underlayment, but the most common calls we get are for IKO Cambridge, IKO Dynasty, and IKO Nordic installations. The underlayment type matters more than the shingle model. IKO’s current synthetic lines include StormShield and GoldShield, both of which hold up far better than the older 15-pound and 30-pound felt that IKO installations in Los Angeles used before synthetics became standard around the mid-2000s.

Here’s the compatibility gotcha: IKO’s newer synthetics have a different slip resistance and fastener-hold profile than traditional felt. If a prior repair was done with standard felt under IKO shingles, it may not lay flat at the eaves and valleys the way IKO’s own material would. We match what your roof actually needs, not just what’s cheap at the supply house. We also work with GAF, Owens Corning, and CertainTeed systems, so if your roof has mixed materials from a past patch job, we can sort out what belongs where.

Brennan Roofing is an independent local contractor. We install IKO products and IKO-compatible materials, but we’re not affiliated with IKO’s corporate warranty program. That said, we install to the manufacturer’s published specs so your IKO warranty stays intact where it applies.

Signs Your IKO Underlayment & Deck Repair Is Failing

• Water stains on ceilings after rain. This is the classic first signal. By the time water is visible inside, the underlayment has already been breached and the decking underneath is likely wet. In Los Angeles, we get these calls most often after the first real storm of the season, when roofs that limped through summer finally get tested.
• Soft or spongy spots when walking the roof. If the decking flexes underfoot, the OSB or plywood has absorbed enough moisture to lose structural integrity. We see this concentrated around valleys, pipe boots, and where old satellite dish mounts were never sealed properly.
• Shingle edges curling or lifting at the eaves. This often means the underlayment at the drip edge has deteriorated and water is wicking back underneath. The shingles aren’t the problem; the layer below them is.
• Granules in the gutters paired with dark streaks on the decking. Granule loss is normal wear, but when you can see dark, damp-looking patches on the wood underneath, you’re looking at active moisture intrusion.
• Musty odor in the attic after rain. Trapped moisture in the decking breeds mildew. If the attic smells like a damp basement, the underlayment is likely failing even if you can’t see the water yet.

Replacement Cost & What’s Included

For Los Angeles homeowners, here’s what you’re looking at in real dollars:

• Underlayment replacement only (sectional, 100-300 sq ft): $450 – $900
• Decking repair (replace 1-2 sheets of OSB or plywood, plus underlayment): $700 – $1,200
• Full underlayment replacement on a smaller LA ranch (900-1,200 sq ft): $1,200 – $1,800
• Larger two-story homes or steep-slope roofs: $1,800 – $3,200+

The price moves based on three things: how much decking has to come out, whether we’re matching IKO’s synthetic underlayment or upgrading to it from old felt, and access. A steep pitch in Silver Lake costs more than a low slope in the Valley because the job takes longer and requires different safety setup. Every quote is a written, line-item price before any work starts. No change orders at the door, no surprises. The work is covered by our 365-Day Done Right Promise in writing for one full year, and we come back at no charge if anything fails in that window.

DIY or Call Us?

Here’s the honest split. A homeowner can safely do two things: look for visible water stains inside the house and check the attic for damp decking after a storm. That’s it. Walking the roof to probe for soft spots is where we’d tell you to stop. Los Angeles roofs with Spanish tile or steep pitches are genuinely dangerous to walk without fall protection, and we’ve watched experienced roofers slip on loose granules. The other issue is that partial DIY repairs around underlayment tend to fail at the seams. If underlayment isn’t lapped and fastened correctly at the eaves, valleys, and penetrations, water finds its way in within a season. That’s a roof we end up fixing twice, and nobody wants to pay for the same roof twice.

If you suspect underlayment or decking failure, call us at (361) 320-9467. We’ll inspect it, show you photos of what’s actually going on, and hand you a written price before anything gets touched.

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