IKO Underlayment & Deck Repair Nationwide

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

We stock and install IKO-compatible underlayment and deck repair materials throughout Los Angeles, with most underlayment replacements running $1,800 – $4,200 depending on roof size and deck damage. Same-week scheduling is standard for us, and we keep IKO’s Armourbase and StormShield lines on our trucks. Most owners discover the problem after a leak shows up on the ceiling following a heavy rain, or when they climb up for a gutter cleaning and feel soft spots underfoot. If your IKO shingles are lifting, curling, or you’re seeing water stains inside, the underlayment or deck sheathing underneath is usually the culprit.

Call (213) 674-2890

Key Takeaways:

• IKO underlayment replacement in Los Angeles typically runs $1,800 – $4,200 installed
• Deck repair adds $85 – $140 per sheet of plywood or OSB replaced
• We stock IKO Armourbase, StormShield, and GoldShield lines for immediate install
• Every job includes a written price before work starts and a written guarantee on the repair
• Greg Holloway and our crew have handled IKO systems across LA County for over a decade

Which IKO Models This Applies To

IKO builds their underlayment systems to work across their full shingle lineup, but the compatibility details matter more than most homeowners expect. The Armourbase line (formerly called GoldBase) is the standard synthetic underlayment spec’d under IKO’s Cambridge, Dynasty, and Nordic architectural shingles. StormShield is their peel-and-stick ice and water barrier, and it’s what we recommend for the first six feet of roof edge in LA’s hillside zones where wind-driven rain actually hits harder than most people assume. If your home was built with IKO’s Marathon or Crowne Slate lines, you’re still dealing with the same underlayment family, but the deck fastening pattern changes.

Here’s the compatibility gotcha we see regularly: older IKO roofs in Los Angeles were often installed with 15-pound felt underlayment because code allowed it at the time. That felt breaks down in our heat cycles, and IKO’s newer synthetic lines are a direct upgrade, but you can’t just slap synthetic over failed felt without checking the deck first. We identify what you have by pulling a ridge cap or looking at the exposed underlayment in the attic at the eave line. IKO prints their name and product code right on the roll, so if you’ve got leftover material in the garage, that label tells us exactly what’s up there.

On the OEM-versus-aftermarket question: for IKO specifically, we install IKO-branded underlayment whenever the roof still has IKO shingles above it. Mixing brands doesn’t void any warranty in practice, but IKO’s synthetic underlayment is engineered to match their shingle weight and nail-holding characteristics. Aftermarket equivalents like GAF FeltBuster or CertainTeed DiamondDeck work fine physically, but if you’re already invested in an IKO roof, the brand-matched underlayment is the safer call. We carry IKO, GAF, Owens Corning, and CertainTeed underlayment on the truck, plus full shingle lines from seven manufacturers including IKO, Atlas, Tamko, and Boral.

Signs Your IKO Underlayment & Deck Repair Is Failing

• Water stains on ceilings or walls after rain. This is the classic signal that underlayment has failed somewhere above. By the time water reaches your drywall, it’s already passed through the shingles, underlayment, and decking, which means the repair has three layers to address, not one.
• Soft or spongy spots when you walk the roof. Deck sheathing rots from the top down when underlayment fails. Los Angeles’s wet winters followed by hot, dry summers create a cycle where plywood delaminates slowly, and by the time you feel it flex, that sheet needs replacement.
• Visible lifting or curling shingles at the eaves. IKO shingles rely on the underlayment as a secondary water barrier. When the underlayment wrinkles or pulls away from the deck, the shingles above it lose their flat base and start to telegraph that movement upward.
• Granules in the gutter after every rain. Some granule loss is normal for any asphalt shingle, but heavy accumulation means the shingle surface is degrading faster than it should. In LA’s Santa Ana winds, that abrasive dust gets driven under shingle edges and accelerates underlayment wear.
• Attic moisture or daylight visible through the deck boards. If you can see light through the roof from inside the attic, the underlayment is gone in that spot, period. This is the one to act on fastest, because the deck is now fully exposed to every rain event until it’s fixed.

Replacement Cost & What’s Included

For a typical Los Angeles home with a 1,500 – 2,200 square foot roof, IKO underlayment replacement runs $1,800 – $4,200 installed. The spread comes from three things: how much of the deck needs replacement, whether we’re pulling the existing shingles or working from the top down, and roof pitch. A simple one-story ranch in the Valley on a 4/12 pitch lands at the lower end. A two-story home in Silver Lake with a steep pitch and multiple valleys lands higher. Deck repair adds $85 – $140 per 4×8 sheet of CDX plywood or OSB, and most failed-underlayment jobs need at least two or three sheets replaced at the eaves where water sat longest.

Here’s what that price includes, every time: removal and disposal of the old underlayment, inspection of every exposed deck seam, replacement of any rotted sheathing, installation of IKO Armourbase or StormShield to manufacturer spec, and re-installation of your existing shingles if they’re still serviceable. If the shingles are too far gone, we’ll tell you that before we start, not after. Tell you the price before we touch the roof, that’s the only way we know how to start. Every job gets a written guarantee on the repair, and if anything fails inside the 365-Day Done Right Promise window, we come back at no charge.

DIY or Call Us?

What you can safely do yourself: check the attic for daylight, look for water stains on the underside of the deck, and snap photos of any shingle lifting from the ground or a ladder. That’s genuinely useful information that helps us quote accurately over the phone. What we don’t recommend: removing shingles to inspect underlayment yourself. Steep roofs in Los Angeles hillside neighborhoods like Mount Washington or Echo Park are dangerous without harness training, and prying shingles loose without knowing how to re-seal them leaves you worse off than you started. Underlayment work also requires specific fastening patterns and overlap measurements that IKO specifies down to the inch.

Deck repair is the same story. Cutting out rotted sheathing looks straightforward until you realize the rafter spacing on older LA homes doesn’t match modern sheet dimensions. If you’re comfortable with basic roof maintenance, great, check what you can. If you want this done right without a second repair six months from now, call us at (213) 674-2890 and we’ll give you a written estimate before any work begins.

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