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Owens Corning Home Additions & ADU: The San Antonio Owner’s Guide
Mason Remodeling Co San Antonio installs Owens Corning-specified additions and ADUs across San Antonio for $45,000 to $130,000 depending on square footage, foundation work, and finish level. Most owners call us after discovering a failed or underperforming component in their existing addition, whether that’s insulation that’s no longer holding R-value in a Texas attic or siding that’s warped after a decade of San Antonio sun. We stock Owens Corning sheathing, insulation, and siding-compatible materials on our trucks, and we match the right product to your existing structure before you spend a dime.
Key Takeaways:
- Installed addition or ADU work in San Antonio runs $45,000 to $130,000
- We carry Owens Corning-specified insulation, sheathing, and siding materials
- Every quote is written, line-itemed, and delivered before work starts
- 365-Day Done Right Promise: if it’s not right within a year, we fix it at no cost
- Your crew’s name and photo arrive before they do, per the Threshold Standard
Which Owens Corning Models This Applies To
Owens Corning doesn’t make “additions” as a single product, so what you’re actually matching is the material system: Foamular or FOAMULAR NGX rigid insulation, Thermafiber mineral wool for fire-rated walls, and the EcoTouch or PINK fiberglass batts that most San Antonio additions were built with over the last 20 years. The gotcha here is R-value matching. If your original addition was insulated with R-13 batts in the walls and R-30 in the ceiling, swapping in anything thinner changes your cooling load, and in San Antonio that shows up on your CPS Energy bill by July.
For siding, the Owens Corning line that matters is the one with the color and profile stamped on the back of a removed panel. We match that number before ordering, because two “beige” panels from different production years won’t sit flush, and you will see the seam every morning. When the original panel is discontinued, we spec a compatible aftermarket equivalent with the same reveal and thickness. We are an independent contractor, not a Owens Corning dealer, so our recommendation is whichever product actually holds up on your wall, not whichever one carries a bigger rebate.
Styles & brands we work with
Signs Your Owens Corning Home Additions & ADU Is Failing
- Siding that’s chalky or brittle at the edges. Ten or more years of San Antonio UV turns the surface layer of polymer siding into a powder that rubs off on your hand. The panel still looks fine from the street until a hail storm turns it into a punch card.
- Rooms that never hold temperature. If your addition is 15 degrees hotter than the main house by 4 p.m. in August, the insulation has either settled, been chewed through, or was under-spec’d from the start.
- Drywall nails popping along addition walls. This is usually framing movement from San Antonio’s expansive clay soil, but the fix often involves re-securing sheathing and re-taping, which means matching the original Owens Corning sheathing thickness.
- Moisture staining at the base of siding. The weep screed or starter strip failed, or the siding was run too close to grade. Water wicks up behind the panel and does its slow work on the sheathing.
- Higher electric bills with no new appliances. Attic insulation in older San Antonio additions was often blown in once and never topped up. R-30 becomes R-19 after enough compression and roof traffic.
See the difference
Before
After
Before
After
Before
AfterReplacement Cost & What’s Included
For San Antonio, a full addition or ADU project lands between $45,000 and $130,000. The spread comes from three things: whether you’re on a slab or pier and beam (pier and beam runs higher for structural work), whether the city requires a full plan review through Development Services, and what finish level you want. A detached ADU with a kitchenette starts pushing toward the top of the range fast.
Our written price includes every line: permits, foundation, framing, Owens Corning-specified insulation and sheathing, siding or stucco to match, electrical, plumbing rough-in where applicable, and finish work. The price we hand you is the price you pay. If we find something in the wall once we open it, we stop and talk to you before anything else happens. Every project carries our 365-Day Done Right Promise, which means if something fails within a year of completion, we come back and make it right at no charge.
| Project Type | San Antonio Installed Range |
|---|---|
| Home Addition (bump-out, bedroom, or bath) | $45,000 – $130,000 |
| Detached ADU Construction | $90,000 – $220,000 |
| Garage Conversion to Living Space | $30,000 – $80,000 |
| Siding Replacement (Owens Corning-compatible, 500 sq ft) | $3,500 – $9,000 |
| Insulation Top-Up or Replacement (existing addition) | $1,200 – $4,500 |
DIY or Call Us?
For insulation and siding work, the honest split is this: you can inspect. You can check for gaps where siding meets windows, look for soft spots in sheathing from the crawlspace, and note which rooms heat up first. What you shouldn’t DIY is removing structural sheathing, re-flashing a roofline, or pulling siding off a two-story addition on a ladder in San Antonio heat. Falls from ladders are the leading cause of homeowner injury on this exact kind of job, and what saves you $400 on a Saturday can cost you a summer.
If you see buckling, water staining, or rooms that won’t hold temperature, call (254) 269-5071. We’ll send a crew with names and photos you already have, a written quote you can hold onto, and the right Owens Corning-specified material for the job.
FAQs
Siding typically lasts 20 to 30 years in San Antonio, but the UV exposure here shortens that on west-facing walls, and insulation performance degrades faster when attic ventilation is poor. Call (254) 269-5071 and we’ll inspect what you have before you replace anything.
In about half the cases we see, the problem is localized, which means a repair is possible: one wall of siding, one section of attic insulation, one re-flashed window. If the framing or sheathing is compromised, replacement is the only safe option. We’ll show you what we found and let you decide.
A straightforward single-room bump-out runs 6 to 10 weeks from permit to final walkthrough in San Antonio. A detached ADU can run 4 to 6 months depending on plan review timing with the city. We’ll give you a written schedule with the same line-item detail as the price.
We keep Owens Corning-specified insulation, sheathing, and common siding profiles in our San Antonio inventory so that smaller repairs don’t wait on a supplier order. If your panel or batt size isn’t on a truck, we’ll have it within a week and you’ll know the exact day we return to install it.
Written by Isaac Pruett, Owner, Mason Remodeling Co San Antonio at Mason Remodeling Co San Antonio, serving San Antonio and nearby areas.
