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Flat & low-slopeFree roof inspection with deck photos before we talk money - GAF and Owens Corning certified installation
Owens Corning Underlayment & Deck Repair: The Miami Owner’s Guide
We stock and install Owens Corning-compatible underlayment and deck repair materials throughout Miami, with most installations priced between $450 and $1,800 depending on how much decking has failed. We can typically assess your roof within one business day and complete the repair as soon as the deck is dry enough to work on safely. Most Miami homeowners discover the problem after a leak shows up on the ceiling or when a roofer peels back shingles and finds rotted OSB underneath. The underlayment and the deck beneath it fail quietly, long before you see water inside the house.
Which Owens Corning Models This Applies To
Underlayment and decking are not model-specific the way a thermostat or a burner assembly would be, but the Owens Corning shingle system on your roof dictates which underlayment is rated to work with it. If your Miami home has Owens Corning Duration, Oakridge, or TruDefinition shingles installed, you need a synthetic underlayment that carries a high-temperature rating, typically 240°F, because attic heat in a Miami summer pushes surface temperatures well past what felt-based products can handle. We match the underlayment spec to the shingle line, not just whatever roll is on the truck.
One compatibility gotcha we run into in Miami all the time: older Owens Corning installations used 15-lb felt underlayment, which Owens Corning has largely moved away from in favor of synthetic products. If you are repairing a section of decking on an older roof, we need to verify whether the existing underlayment is felt or synthetic. Mixing types on the same deck plane creates uneven thermal movement and can void the shingle warranty. Grant Whitlock personally checks the exposed underlayment on every deck repair in Miami so we are matching what is already up there, or replacing a full run when the types cannot be bridged.
On the decking side, Miami building code requires minimum 7/16-inch OSB or 15/32-inch plywood, but we refuse to install anything thinner than 15/32-inch nominal when we are replacing sections. The thinner sheets sag between rafters within a few Miami wet seasons. For homes in flood-prone neighborhoods like Brickell or Coconut Grove, we also recommend checking the roof deck fastening pattern while we are up there. A deck that meets the minimum thickness but was stapled instead of nailed will fail under uplift wind loads during a storm.
Styles & brands we work with
Signs Your Owens Corning Underlayment & Deck Repair Is Failing
- Water stains on the ceiling that appear away from any pipe or vent. This is usually the deck itself rotting through and letting water run along a rafter before it finds a seam in the drywall. The stain location rarely points directly to the roof damage.
- Soft spots you can feel from inside the attic. If you can push on the deck from underneath and it flexes or flakes, the OSB has absorbed moisture and lost its structural integrity. This is the most direct sign that a deck section needs replacement, not just a patch.
- Granules from your Owens Corning shingles collecting in the gutter after a storm. Granule loss accelerates when the underlayment below is trapping moisture, causing the shingle mat to overheat and shed its protective surface.
- Visible daylight coming through the attic deck near pipes, vents, or the chimney chase. This means the underlayment has torn or pulled away at a penetration, and the deck around it is likely soft from repeated water intrusion.
- Shingles that look wavy or uneven from the curb in Miami’s afternoon sun. Rippled shingles almost always mean the deck underneath is swelling or warping. The underlayment cannot bridge a moving deck, and the shingle line telegraphs every imperfection.
Replacement Cost & What’s Included
For a typical Miami deck repair covering 50 to 100 square feet, including new Owens Corning-compatible synthetic underlayment, OSB replacement, and reinstallation of the existing shingles where they are still serviceable, you should expect to pay between $450 and $1,200. Larger sections that require full shingle replacement on top of the deck work run $1,200 to $1,800 and up. The range comes down to three things: how much deck is rotted, whether we have to remove shingles beyond the obvious damage to find solid decking, and whether the existing underlayment type can be matched locally.
Every quote from Mercer Roofing Co Miami is a written price before any work starts, and it includes the new underlayment, the decking material, the fasteners rated for Miami wind uplift, and the labor. The written guarantee covers 365 days from the day work is completed. If the repair fails in that window, we come back at no charge and make it right under the Done Right Promise.
Will the price change once work starts? No. The number we hand you is the number you pay. If we find additional rotted deck beyond the quoted scope, we do not start that extra work until we show you what we found and give you a new written price. Grant Whitlock is on every Miami deck inspection himself, so the price you get is based on what is actually up there, not a guess from the ground.
See the difference
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AfterDIY or Call Us?
Replacing roof decking and underlayment is not a weekend project. You are working at roof height, removing structural material, and then reinstalling it before the next Miami afternoon downpour. If you tear off shingles and find more rot than you expected, you now have an open wound in your roof with rain on the radar. That is how a $600 repair becomes a $6,000 ceiling replacement. The safest DIY step is inspection: get a flashlight into the attic, look for soft or stained deck, and check the gutter for granule buildup. That tells you enough to know if a call is warranted.
We handle the actual repair because it requires working at height with the right fall protection, and because the underlayment has to be flashed correctly at every penetration. A bad flashing job under new underlayment leaks within months, and you will not see it until the drywall tells you. Call (850) 753-2996 for a free estimate. We will walk the roof, show you what we found, and give you a written price before anything else happens.
FAQs
Synthetic underlayment on a properly ventilated Miami roof should last 20 to 30 years, which covers the full life of the shingle system. Felt underlayment from older Owens Corning installations lasts 10 to 15 years in Miami’s heat and humidity before it starts drying out and tearing. If your roof is more than 12 years old and still on felt, plan to have it inspected.
It depends on what the moisture has reached. If the deck is solid and only the underlayment has torn at a penetration, we can repair that section. If the deck is soft, flaking, or sagging, replacing it is mandatory. We will show you the difference while we are on the roof. Call (850) 753-2996 and we will schedule a free estimate.
A typical deck repair of 50 to 100 square feet takes one full day, sometimes a day and a half if we have to remove shingles across a larger area to find solid decking. We tarp the repair area at the end of every workday, even if the forecast is clear. Miami weather does not give you courtesy warnings.
Yes. Our Miami trucks carry Owens Corning-compatible synthetic underlayment, plus the supplies we’d need for a partial deck replacement on the spot. We also keep GAF and CertainTeed underlayment in stock for homes where the original system used those brands. If your repair needs a product we don’t have loaded that morning, we can usually have it the same day.
No. Mercer Roofing Co Miami is an independent roofing contractor serving Miami and nearby areas. We are not affiliated with Owens Corning. We install and repair using Owens Corning-compatible materials and work within the manufacturer’s installation specifications.
Call Mercer Roofing Co Miami for Your Free Estimate
If you have a soft spot, a ceiling stain, or just want the deck checked before the next hurricane season, call (850) 753-2996. A live person answers, 24/7, every day of the year. You will get a written price before any work starts, and the technician who arrives will already be familiar: we send their name and photo ahead of the visit, and they will show you a photo ID badge at the door before stepping inside. A roof should not be something you worry about – that’s our job.
Written by Grant Whitlock, Owner, Mercer Roofing Co Miami at Mercer Roofing Co Miami, serving Miami and nearby areas.