IKO Underlayment & Deck Repair Nationwide

IKO Underlayment & Deck Repair: The Orange County Owner’s Guide

IKO underlayment and roof deck repair in Orange County typically runs $450 to $1,900 installed, depending on how much decking has failed and which IKO underlayment your roof system calls for. We stock IKO-compatible underlayment on our trucks and can usually get the decking opened up, assessed, and repaired in a single visit. Most homeowners discover the problem the same way: a ceiling stain shows up after a Santa Ana wind event, or a roofing crew peels back shingles during a repair and finds soft, delaminated plywood underneath.

Call (559) 295-5445

What surprises people is that the underlayment itself is rarely the first thing to fail. In Orange County, the marine layer sits on coastal roofs for months, then the inland heat bakes the same membrane through July and August. That cycle breaks down the adhesive bond between underlayment and decking faster than rain ever will. By the time we open the roof, the decking underneath is usually the part that’s given up, and the underlayment is just the last layer hiding it. Greg Holloway has walked enough Orange County roofs to know that cheap underlayment over failing decking is the most common repair he sees on homes built between the late 1980s and early 2000s.

Which IKO Models This Applies To

IKO underlayment products break into two families: synthetic and felt-based. The synthetic lines, including IKO’s StormShield and GoldShield series, carry peel-and-stick self-adhered versions rated for high-temperature exposure, which matters in Orange County’s inland valleys. The felt-based lines, like Armourbase 15 and Armourbase 30, are traditional asphalt-saturated products that remain common on older Orange County roofs where the original build spec called for them.

The compatibility gotcha with IKO underlayment is the decking condition underneath it. Self-adhered membranes like StormShield grip only as well as the surface they’re stuck to. If the plywood or OSB below has started to delaminate or surface-flake, the membrane can look intact while it quietly lets water travel underneath. We’ve opened roofs in Mission Viejo where the underlayment peeled back like a bandage because the decking had turned to dry crumble underneath it. Before any IKO underlayment replacement, the decking gets checked with a probe and a moisture meter.

For decking, the OEM-versus-aftermarket question is simpler than most roofing parts. IKO doesn’t manufacture plywood or OSB. The decking your roof calls for is specified by thickness and grade, not brand. Orange County code commonly requires 15/32-inch CDX plywood or 7/16-inch OSB rated for roof sheathing, and either is an acceptable deck surface under IKO underlayment as long as it’s dry, clean, and fastened to current nailing schedules. We stock standard 4×8 sheets in both materials so we’re not sending a runner to the supply yard mid-job.

Tilehurst Roofing Orange County is an independent roofing contractor and is not affiliated with IKO. We install and repair IKO-branded products alongside materials from GAF, Owens Corning, CertainTeed, Atlas, Tamko, and Boral, so the underlayment recommendation matches the roof system already on your home.

Signs Your IKO Underlayment & Deck Repair Is Failing

• A soft or springy section of roof. When the decking loses structural integrity, you’ll feel it give slightly underfoot. This means the plywood or OSB has absorbed moisture long enough to break down the wood fibers.
• Stains on ceilings or walls that appear after rain, but sometimes days later. Water moves slowly through failed decking and underlayment, so the leak may show up long after the storm ended.
• Shingles lifting or curling at the edges. Shingles are nailed to the decking. When the decking rots, nails lose their bite, and the shingle edges start lifting even without wind.
• Sagging visible from the ground along the eave or valley lines. This is a late-stage decking failure and usually means multiple sheets are compromised. It needs an inspection fast, because the next heavy rain will find its way through.
• Dark streaks or visible separation at underlayment seams in the attic. If you can see the underside of the decking from your attic, look for dark water tracks, mineral staining, or daylight coming through gaps that shouldn’t exist.

Replacement Cost & What’s Included

For Orange County homes, expect to pay $450 to $900 to replace underlayment on a single roof section, like a 200-square-foot area around a valley or penetration. Adding decking repair pushes the range to $800 to $1,900 depending on how many sheets come out. A full re-deck on a larger Orange County roof generally starts around $2,400, though most repair jobs don’t require it.

Here’s what drives the range and what’s included in our price:

• Single-sheet decking replacement with new fasteners: $180 to $320 per sheet
• IKO-compatible synthetic underlayment, installed: $2.50 to $4.00 per square foot
• Peel-and-stick underlayment in valleys and around penetrations: $1.50 to $2.50 per linear foot
• Disposal of rotted decking and old underlayment: included
• Written itemized estimate before any work starts: included, always

The price you receive is the price you pay. No change orders show up after we open the roof unless you approve them in writing first. And every repair leaves with a written guarantee. If the fix fails inside the guarantee period, we come back at no charge under the 365-Day Done Right Promise. For a more precise number for your specific roof, call (559) 295-5445 and we’ll walk the property and give you a firm figure.

DIY or Call Us?

What you can safely check yourself: visible attic stains, soft spots you can feel from a ladder at the eave, and any shingles that look obviously lifted. These observations help our crew understand what you’re seeing before we arrive.

What we don’t recommend: opening the roof yourself. Roof decking repair means cutting out rotted sheets, matching the remaining deck thickness, and re-fastening to code. Get the nailing pattern wrong on a roof in Santa Ana wind territory and you’ve created a peel point. Working on a roof also means working at height, and the combination of a damaged deck and a homeowner without roof experience is a bad one. The work itself is fast for a crew doing it every week. Call (559) 295-5445, tell us what you’re seeing, and we’ll give you a straight answer about whether it needs a look this week.

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