GAF Underlayment & Deck Repair Nationwide

GAF Underlayment & Deck Repair: The Orlando Owner’s Guide

We stock and install GAF-compatible underlayment and decking products across Orlando, and a typical underlayment and deck repair runs between $650 and $1,900 depending on how many sheets of plywood or OSB need replacement and how much of the roof we have to peel back. Most jobs are finished in one day once we get the materials up there. What usually tips an Orlando homeowner off that something’s wrong is a ceiling stain after a heavy summer downpour, or shingles that feel spongy when you walk past them on a ladder and notice a dip. By the time water shows up inside, the underlayment has already given up the fight and the decking underneath is getting soft.

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The thing about GAF roofing systems is that the underlayment is a critical part of why their warranties mean anything. GAF builds their systems around specific components working together: the shingle, the underlayment, the decking, the flashing. When one layer fails, the others aren’t far behind in this Florida humidity. If you’re seeing signs of trouble, call us at (850) 757-3564 and we’ll put a written estimate in your hand before any work starts.

Which GAF Models This Applies To

If your roof has GAF Timberline HDZ, Timberline UHDZ, Timberline NS, or Royal Sovereign shingles, chances are high your underlayment is a GAF product too: Deck-Armor, FeltBuster, Shingle-Mate, or Tiger Paw depending on what the installer chose and what the product line specified. These underlayments have specific widths and roll lengths, and they’re not all interchangeable with each other. Deck-Armor, for example, comes in 48-inch rolls and installs with plastic cap nails, while FeltBuster is a 36-inch synthetic that’s more common on reroofs where someone wanted to keep the cost down a bit.

Here’s a compatibility gotcha that matters in Orlando: GAF’s high-performance underlayments like Deck-Armor are breathable, which helps moisture escape rather than collect under the shingles. But breathable underlayment only works correctly if the roof’s ventilation is set up the way GAF specifies. We’ve walked too many Orlando attics in Conway and Belle Isle where the ridge vent was undersized or the soffit vents were painted shut. The underlayment wasn’t the failure point. It was trapped moisture from poor airflow, and the decking paid the price. A GAF-compatible repair means checking that part too, not just slapping new materials over the same problem.

For the deck itself, we use exterior-grade plywood or OSB rated for roofing, thickness-matched to what’s already up there. Most Orlando roofs built in the last 20 years use 15/32-inch or 1/2-inch sheathing, but older homes in College Park and Audubon Park sometimes have 3/8-inch plywood or even spaced board sheathing that needs a different approach. Matching the thickness matters because a roof deck that’s thicker than what the trusses were designed for adds unnecessary dead load, and a thinner one won’t pass a nail pull-out test.

We’re an independent Orlando roofing company, not affiliated with GAF, but we install and repair using GAF materials every week and know their specs. We also work with Owens Corning and CertainTeed underlayments for homeowners whose systems use those brands.

Signs Your GAF Underlayment & Deck Repair Is Failing

• Stains on the ceiling that show up hours or days after rain. This means water is getting past the shingles and underlayment and sitting on the decking long enough to wick through. The leak you see on the ceiling is often 6 to 10 feet from where the water actually entered the roof.
• Shingles that look wavy or don’t lie flat. When decking gets water-damaged and swells, it can push shingles up unevenly. What looks like a shingle problem is very often a deck problem hiding underneath.
• A musty smell in the attic, especially in the morning. Orlando’s humidity means any water that gets under the underlayment doesn’t dry out quickly. If the attic air smells like a wet towel that sat in the car, we need to look at the decking.
• Soft spots you can feel underfoot. Don’t walk a roof unless you know how to do it safely. But if you’re already up on a ladder or a roofer has you up there, a section that flexes more than the surrounding area means the decking has lost structural strength and needs replacement, not just a patch.
• Granules in the gutters paired with dampness at the edges. Granule loss tells you the shingles are aging. Damp edges where the decking meets the fascia tell you underlayment at the eaves has been wicking water upward. Together, they mean the system is past its serviceable life in this climate.

Replacement Cost & What’s Included

In Orlando, replacing a section of GAF underlayment and the damaged decking beneath it typically runs $650 to $1,900. The range is driven mostly by how many 4×8 sheets of decking need to come out and how complicated the roof geometry is. A single sheet replacement with new underlayment and shingle reinstallation around it will land at the lower end. A roof with four or five soft sheets, a valley involved, and step flashing that needs rebuilding will push toward the higher end.

Every quote from Mercer Roofing Co Orlando breaks down the material and labor lines separately, and the number we put in writing is the number you pay. That means the underlayment itself is itemized: whether it’s Deck-Armor, FeltBuster, or tiger paw for the slope in question. The plywood or OSB is itemized by sheet count. The shingle reinstallation, the cap nails, the sealant, the dump fees, all of it. You’ll know what every dollar buys before we start. And every repair carries our 365-Day Done Right Promise in writing.

DIY or Call Us?

You can safely check a few things from the ground or from inside the attic: look for daylight coming through the decking, feel for soft spots on accessible areas, note where water stains are concentrated on the roof deck from inside. What you shouldn’t do is peel back shingles and patch underlayment yourself. The reason is simple and it’s not about making work for us. A roof opened up in the wrong weather becomes a bigger leak than the one you started with, and Orlando can turn from clear sky to cloudburst faster than a homeowner can get new underlayment rolled out and re-nailed properly. Improperly lapped underlayment or nails placed outside the nailing pattern void the GAF system warranty and create a moisture trap that rots the new decking you just put down.

Grant Whitlock will tell you the same thing he tells every homeowner who calls: “A roof shouldn’t be a mystery, let’s talk about what’s actually up there.” We’ll inspect it, show you photos of what we find, and give you a written price. Call (850) 757-3564 and you’ll get a person on the line who can schedule a time that works for you.

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