IKO Underlayment & Deck Repair in San Antonio, TX

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

IKO underlayment and deck repair in San Antonio typically runs $1,800-$4,200 installed, depending on how much decking needs replacement and whether we’re working around existing shingles. We stock IKO-compatible ArmourGard and GoldShield underlayment on every truck, and most deck repairs are same-day jobs. Homeowners usually discover the problem after a hard rain: water stains on the ceiling that trace back to a section where the underlayment has torn or the decking has softened beneath it.

Call (833) 756-5022

Which IKO Models This Applies To

IKO’s system is built around three underlayment tiers, and matching the right one matters for your warranty. The ArmourGard series is the synthetic base layer found under IKO Cambridge, Dynasty, and Nordic shingles from roughly 2012 forward. GoldShield is the premium high-temp option spec’d for IKO’s Grandeur and Royal Estate lines, and it’s what we see most often on the tile-adjacent installs common in Alamo Heights and Terrell Hills. The older Marathon and Marathon Ultra lines from the 2000s typically ran with IKO’s earlier felt-based products, which are now discontinued; for those, we source a synthetic equivalent that meets IKO’s current breathability specs without trapping the humidity that San Antonio’s spring storms push into attic spaces.

To identify what you’ve got, we look for the IKO lot number on the shingle bundle or the underlayment roll edge, then cross-check against the install date. A 48-inch wide roll with the gold stripe is GoldShield; ArmourGard runs 42-inch with a gray printed face. We’re an independent service provider, not affiliated with IKO, but we keep their full spec library on hand because half the roofs we touch in Bexar County have IKO products on them.

The OEM-versus-aftermarket question comes up regularly. For underlayment, we prefer OEM IKO synthetics when the roof is still under manufacturer warranty, since mixing brands can void coverage. For decking, it’s straightforward CDX or OSB rated for roof exposure, and we don’t play games with substitutions.

Signs Your IKO Underlayment & Deck Repair Is Failing

• Water stains that appear in straight lines or rectangular patches. This pattern usually means the underlayment has separated at a seam or fastener line, letting water run along the decking until it finds a penetration point. In San Antonio, we see this most after hail events that flex the decking enough to tear the underlayment without dislodging shingles.
• Sagging or spongy spots when you walk the roof. The OSB or plywood decking has absorbed moisture and begun to delaminate. On older homes in Monte Vista or King William, we find this where decades of solar heat have baked the adhesive in the decking panels, making them more vulnerable once water gets past the underlayment.
• Granules collecting in gutters but no visible shingle damage. The shingles are sliding on a compromised underlayment surface, abrading from beneath. IKO’s synthetic underlayments have a textured face designed to prevent this; when that texture wears smooth or the underlayment shifts, the shingle backing grinds itself down.
• Mold or mildew odor in the attic during summer months. South Texas humidity finds every gap. A torn underlayment in a valley or around a chimney lets moist air into the decking cavity, and without proper ventilation, that moisture breeds mold before it ever drips through the ceiling.
• Shingles lifting at the edges despite intact sealant strips. The decking beneath has warped or sunk, breaking the flat plane the shingles need to lie on. This is common where original decking was 3/8-inch and code now requires 7/16-inch minimum; the thinner panels flex more under thermal cycling.

Replacement Cost & What’s Included

Here’s how pricing breaks down for IKO underlayment and deck repair work in San Antonio:

The spread depends on three things: how much decking needs replacement versus sistering, whether we’re working around existing IKO shingles that must be removed and reinstalled carefully, and access complexity (steep pitches, multi-story, or tight lots like those in Tobin Hill). Our estimates include all materials, labor, disposal, and the 90-Day Done Right Promise in writing. The number we quote is the number on the invoice. No surprises.

We back every underlayment and deck repair with our written workmanship guarantee. If it’s not right, we make it right. No paperwork, no arguing.

DIY or Call Us?

There’s a safe middle ground here, and then there’s the point where DIY turns risky.

What you can check from the ground or attic: look for daylight showing through the roof boards, feel for damp insulation, and note any musty smells. A moisture meter from the hardware store can confirm suspicions without you setting foot on the roof. These checks tell you whether you have a problem, not how to fix it.

What goes wrong when homeowners push further: walking a pitched roof with compromised decking is dangerous, full stop. The soft spot you can’t see from the ladder is the one that gives way. Removing shingles to access underlayment without understanding the IKO fastening pattern tears more than it fixes. And synthetic underlayments require specific overlap and fastening schedules; get it wrong, and you’ve created a vapor trap that rots the decking faster than the original leak.

We carry IKO-compatible underlayment and decking on every truck. Most repairs are done in a single visit. If you’re seeing the symptoms, call (833) 756-5022. We’ll walk through what you’re seeing, and if it makes sense to look, we’ll get there fast. A roof either holds or it doesn’t. We build ones that hold.

FAQs