Owens Corning Spray Foam Insulation in San Marcos: What to Know First
We provide independent Owens Corning spray foam insulation in San Marcos, with most jobs scheduled within 48 hours and completed same-day. Most attic insulation jobs in a home this size run between $2,800 and $5,400 for open-cell spray foam, and we put a written price in your hand before anyone lifts a tool. This page is for homeowners who already have Owens Corning materials in their building envelope and need a technician who understands how those specific products age in Central Texas heat. Call (737) 337-8049 or text us - a live person answers, 24/7.
How Owens Corning Products Fail - and How We Fix Them
- Fiberglas™ batts compressed by previous blown-in retrofits. We find this in San Marcos homes built 2005-2015 near the Texas State corridor: a contractor blew cellulose or loose-fill fiberglass over existing Owens Corning Fiberglas™ batts without checking compression. Compressed batt loses 30-50% of its labeled R-value because the trapped air pockets collapse. We remove the compromised layer, air-seal the top plates and can-light penetrations, then install open-cell spray foam to the full designed thickness.
- PINK Next Gen™ Fiberglas losing adhesion at roof decks above cathedral ceilings. The formaldehyde-free binder in this series can release from OSB sheathing when attic temperatures exceed 140°F repeatedly, which happens in San Marcos from June through September. The batt sags, creating a convection channel. We strip the failed material, verify the roof deck ventilation baffles are intact, and spec closed-cell spray foam directly to the deck - no air gap, no future sag.
- AttiCat™ PINK blown-in settling below top plates in older slab-on-grade homes. The Blown-In-Blanket System (BIBS) works when installed to full depth, but in the ranch-style homes common west of I-35, we regularly find the material settled 4-6 inches below the top plate, leaving the wall-to-ceiling junction thermally unprotected. That junction is where San Marcos homes lose the most conditioned air. We remove the settled material, seal the top plate with one-part foam, then spray open-cell to the full stud bay height.
- FOAMULAR® rigid board gaps at rim joists in pier-and-beam retrofits. Owens Corning’s XPS rigid foam is a fine product, but cut-and-cobble jobs at rim joists almost always leave seams and perimeter gaps. In crawl spaces off Wonder World Drive and Hopkins Street, we’ve found carpenter ants exploiting those gaps for passage. We pull the board, treat the wood, and spray closed-cell foam to create a monolithic seal - no seams, no pest highway.
- WeatherLock® Flex underlayment trapping moisture when spray foam is applied to roof decks from the interior. This synthetic underlayment is vapor-impermeable. When a homeowner or previous contractor sprays closed-cell foam directly to the roof deck underside without verifying the exterior layer’s permeability, moisture can accumulate in the sheathing during San Marcos shoulder seasons. We probe the deck with a moisture meter, replace compromised sheathing if needed, and spec a ventilated assembly or use open-cell foam with a vapor-smart exterior.
Our Owens Corning Spray Foam Insulation Process

- 1
Call and scope. You describe the space - attic, crawl, rim joist, garage ceiling. We schedule a site visit, usually within 48 hours in San Marcos.
- 2
Blower-door test and thermal imaging. We run a blower-door test - a pressurization reading that shows, in one number, how much air your building envelope is losing. Thermal imaging identifies bypasses the naked eye misses. You get the before number in writing.
- 3
Written price and material spec. We specify Owens Corning FOAMULAR® or certified-compatible spray foam based on your assembly, with OEM or quality aftermarket per your approval. The price is flat. No work starts without your signature.
- 4
Air sealing first, then insulation. We seal top plates, can lights, plumbing and electrical penetrations, and rim joist gaps before foam touches the space. The R-value tells you how slow heat moves through the material - the blower-door number tells you whether any of that matters.
- 5
Spray application and real-time thickness verification. Our crew installs to the specified inches, checking with a depth gauge every 100 square feet. We photograph the completed work for your Documented Photo Record.
- 6
Final blower-door test and closeout. We run the door again, hand you a single printed page with before-and-after air-changes-per-hour, and activate your 365-Day Done Right Promise. Written warranty, written scope, no exceptions.
Before
AfterWhat Owens Corning Spray Foam Insulation Costs in San Marcos
| Job Type | Typical Range | What Moves the Price |
|---|---|---|
| Open-cell spray foam, attic (1,500-2,500 sq ft home) | $2,800-$5,400 | Accessibility, existing removal, sheathing repairs |
| Closed-cell spray foam, rim joist (pier-and-beam) | $1,800-$3,200 | Crawl height, moisture damage, pest remediation |
| Closed-cell spray foam, garage ceiling | $2,200-$4,100 | Area, ductwork relocation, fire-rated separation |
| Open-cell spray foam, roof deck (cathedral ceiling) | $4,500-$8,200 | Deck condition, ventilation strategy, finish repair |
| Attic removal + replacement with spray foam | +$800-$2,400 above foam cost | Volume of old material, rodent contamination, disposal |
These are real ranges from jobs we’ve completed in San Marcos and nearby New Braunfels, Kyle, and Buda. Every home is different - the only way to get your exact number is a site visit, and that estimate is free. Call (737) 337-8049 to schedule.
Why San Marcos Homeowners Call Topside Attic Insulation San Marcos for Owens Corning Work

We’re an independent Owens Corning service provider - no factory authorization, no corporate script, just technicians who know how these materials behave in Central Texas attics. Wes Okafor trained in building science at Dawson Technical Institute and has spent two decades diagnosing why attics fail rather than filling them. Our crew carries Owens Corning, Reflectix, and other major brands so we’re never locked into a single product line when your assembly needs something different.
Every job gets the Haven Standard: written price before work starts, documented photo record when we leave, and before-and-after blower-door numbers on applicable jobs. The 365-Day Done Right Promise means if it’s not right, we make it right - backed by a written warranty you hold in your hand, not a website claim. Calls are answered by a live person, 24/7. Background-checked, uniformed technicians. Text updates when we’re en route.
FAQs
Owens Corning’s material warranties cover manufacturing defects in the original product, not subsequent modifications to the building assembly. Adding spray foam to a space that previously held Owens Corning batts or board does not void anything, but it also doesn’t extend coverage to the new material. We document what we remove and what we install so your records are clear. Call (737) 337-8049 if you need help reading your existing warranty language.
Owens Corning manufactures FOAMULAR® rigid board and certifies select spray foam partners; we source compatible open-cell and closed-cell products that meet or exceed the same density and R-value specs. If your job specifically requires FOAMULAR® by name - some HOA or builder warranty situations do - we can spec it. We explain the trade-offs in writing before you decide. Estimates are free.
Repair is cheaper when the existing material is dry, uncompressed, and fully accessible - maybe 30-40% of the San Marcos homes we see. Replacement with spray foam pays back faster when the existing material is settled, moisture-compromised, or installed over unsealed air leaks. We don’t guess; we measure. The blower-door test and moisture probe tell us which path makes sense for your specific house. Call (737) 337-8049 for a free assessment.
Most residential jobs schedule within 48 hours and finish in one day. Two-day jobs involve extensive removal, sheathing repair, or crawl-space remediation. We give you a firm start and end date in writing before anyone arrives - Haven Standard Clause 1. Same-day emergency service is available for situations involving active roof leaks or exposed electrical in the attic.
Yes. We regularly find homes with Owens Corning batts in the attic and Reflectix radiant barrier in the garage, or FOAMULAR® board at the rim joist with competing-brand spray foam at the roof deck. Our material inventory includes Owens Corning, Reflectix, Johns Manville, Knauf, Rockwool, CertainTeed, Icynene, Demilec, and GreenFiber - no proprietary lock-in, no upsell to a single brand. We spec what the assembly needs.
Written by Wes Okafor, Owner, Topside Attic Insulation San Marcos at Topside Attic Insulation San Marcos, serving San Marcos and nearby areas.