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Owens Corning Home Additions & ADU: The San Antonio Owner’s Guide
Owens Corning home additions and ADU projects in San Antonio typically run $45,000 to $130,000 for a full addition, and that covers everything from foundation to finish work including insulation, drywall, roofing, and the Owens Corning materials that go into the envelope. Most homeowners call us after they notice the telltale signs: drafts in a newer addition, a spike in the July electric bill, or water staining where the roof meets the new wall. We stock the Owens Corning insulation, weather barrier, and roofing products needed to fix or build these spaces correctly, and our crew in San Antonio does this work every week.
Which Owens Corning Models This Applies To
If your addition or ADU was built with Owens Corning products, you’re almost certainly working with three main lines: EcoTouch or R-Series fiberglass batts, FOAMULAR XPS rigid board, and either Duration or Oakridge architectural shingles on the roof. The compatibility gotcha most San Antonio homeowners run into is insulation facing. Owens Corning Kraft-faced batts are built for specific stud spacing, and if your original builder used 24-inch on-center framing, standard 15-inch batts won’t seat right. You need to check the paper facing on the existing batts or measure the stud cavity before ordering replacements. For ADU roof decks, Owens Corning’s synthetic underlayment (Deck Defense) and their roof boards are spec’d to the shingle rating, so mixing a 30-year Duration shingle with old felt underlayment voids the manufacturer’s backing.
On the OEM-versus-aftermarket call: for exposed applications like roof decking and exterior rigid insulation, we only install genuine Owens Corning. The R-value per inch and the moisture resistance are tested to spec in Texas heat, and the warranty follows the product. For interior batt work inside a closed wall, quality aftermarket equivalents can save you money, but the density and compression behavior differ. Fiberglass loses R-value when compressed, so a cheap batt stuffed into a shallow San Antonio ceiling cavity can drop from R-30 to R-19 fast. We quote both options and tell you which one actually makes sense for your project.
Styles & brands we work with
Signs Your Owens Corning Home Addition or ADU Is Failing
- Uneven room temperatures between the main house and the addition. This usually means the original batt insulation was compressed, installed with gaps, or never sealed at the rim joist. Heat moves through those gaps, and your AC fighting a phantom load.
- Draft around outlets or baseboards in the added space. That’s a classic sign of missing or failed Owens Corning air barrier. In San Antonio’s humid climate, air leaks don’t just cost money; they pull moisture into the wall cavity and feed mold.
- Water stains at the ceiling-wall transition or around roof penetrations. Owens Corning shingles are solid products, but a bad flashing job at the addition’s roofline will let water chase the seam. You’ll see it weeks after a hard Hill Country storm.
- Musty smell in the ADU after it’s been closed up a few days. This points to zero or insufficient ventilation paired with air leaks. Owens Corning’s system depends on the building envelope being done as a system; when one layer goes, condensation follows.
- Visible ceiling sag or shingle granule loss on the addition’s roof. The roof deck under Owens Corning shingles can’t hold up if the underlayment failed first. In San Antonio’s UV exposure, failed underlayment shows up as loose shingles and granule wash within a few years.
See the difference
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AfterReplacement Cost & What’s Included
For a failed part in an existing addition or ADU, here’s what San Antonio pricing looks like. A full home addition built to Owens Corning spec runs $45,000 to $130,000 all-in, depending on square footage, whether it’s a conditioned space or a garage conversion, and how much of the existing envelope we have to correct. An ADU construction project in San Antonio runs $90,000 to $220,000. If you’re just replacing the failed Owens Corning piece, like re-insulating a single wall cavity, the cost comes in much lower, often a few hundred to a few thousand dollars, depending on demolition access and material thickness. The range on a roof re-sheathing with Owens Corning decking and new underlayment along an addition typically falls in the $8,000 to $20,000 band for a roof replacement on that structure.
We give you a written price before any work starts. That number includes the Owens Corning material, the labor to remove and dispose of the failed part, the install, and our 365-Day Done Right Promise. If it’s not done right, we make it right. Written. Pick up the phone and call (432) 547-6806 for a free estimate on your San Antonio addition or ADU.
DIY or Call Us?
You can safely check a few things. Pull an outlet cover on an exterior wall in the addition and look for gaps around the electrical box. Check the roof for granule wash in the gutters. Measure the R-value printed on any exposed Owens Corning batt in an attic space. That’s useful diagnostic work.
But replacing insulation, roof decking, or underlayment in a San Antonio attic or on a sloped roof is not a weekend project. Attic temperatures hit 130 degrees and higher here. Working with fiberglass requires full skin and lung protection. And any roof work on an addition means you’re on a ladder or a sloped surface. If the part you need is in the roof system, call (432) 547-6806. We’ll send a background-checked technician with the right Owens Corning materials on the truck, and you’ll get a written quote before we touch anything.
FAQs
Owens Corning fiberglass batts and FOAMULAR rigid board have a rated lifespan that matches the life of the building, but only if they’re installed dry and never compressed. In San Antonio, the bigger enemy is moisture from air leaks, not the material itself. If your insulation is trapping humidity, it degrades fast and loses R-value. Call (432) 547-6806 and we’ll inspect it for free and quote you an exact fix.
In some cases, yes. If the failure is an air seal gap or a small section of compressed batt, we can correct it without a full re-insulation. If the roof underlayment or decking is compromised, repair usually doesn’t make sense; we replace the bad section so the Owens Corning shingles keep their warranty. Call (432) 547-6806 and we’ll tell you which one applies to your project.
A single-wall cavity re-insulation in a San Antonio addition is usually a half-day job. A full roof re-sheathing with Owens Corning decking and new underlayment on a typical addition takes two to three days, depending on weather and accessibility. We’ll give you a written schedule with your quote, so you know exactly what to expect. Call (432) 547-6806 to set up your estimate.
Yes. Our San Antonio crews carry Owens Corning R-13, R-19, and R-30 batts, FOAMULAR rigid board in multiple thicknesses, and the standard Owens Corning underlayment products. For shingle-specific jobs we order the exact Duration or Oakridge color match ahead of time, and we’ll confirm that in writing before we start. Call (432) 547-6806 and we’ll get you scheduled.
Written by Luca Romano, Owner, Sawyer Remodel San Antonio at Sawyer Remodel San Antonio, serving San Antonio and nearby areas.
