Demilec Attic Insulation: The San Antonio Owner’s Guide
If your Demilec spray foam or injection foam insulation has failed, delaminated, or is no longer performing, we stock Demilec-compatible materials and can typically complete the removal and replacement within one to two days, depending on attic size. Installed pricing for Demilec-compatible attic insulation in San Antonio generally runs $2.40 to $4.80 per board foot for spray foam, or $1.50 to $3.00 per square foot for blown-in fiberglass or cellulose used to top off or replace failed foam. Most San Antonio homeowners discover the problem the same way: a bedroom that won’t hold temperature, a spike in the July electric bill, or visible gaps where the foam has pulled away from the roof deck.
Key Takeaways:
- Demilec foam can shrink, delaminate, or degrade from improper installation, roof leaks, or sustained attic heat
- We are an independent San Antonio installer, not a Demilec affiliate, and we match material to the specific failure
- Written price before work starts, and the 365-Day Done Right Promise covers every replacement
- Same-week scheduling is available for most Demilec repairs in the San Antonio area
Which Demilec Models This Applies To
Demilec produces two main product families that we regularly service in San Antonio homes: Heatlok HFO, a closed-cell spray foam, and Sealection 500, an open-cell spray foam. The two behave differently in a Texas attic. Heatlok HFO is rigid and structural, expanding to roughly 2 inches per pass; Sealection 500 is softer and more breathable, designed more for sound and air sealing than R-value density. If you’re not sure which you have, a small core sample or measuring the foam’s hardness tells us quickly. Open-cell crushes under finger pressure; closed-cell doesn’t.
Here’s the compatibility gotcha most San Antonio homeowners run into: you can’t easily patch one product with the other. Spraying open-cell over failed closed-cell, or vice versa, creates adhesion problems and moisture trapping. The right call is almost always to remove the failed section and reapply the same Demilec product, or fully top off with blown-in insulation over a stable remaining foam layer. We carry both Demilec lines on the truck, plus a quality aftermarket equivalent for situations where a full removal isn’t practical. When we do use aftermarket, we tell you first and show you the spec sheet.
Signs Your Demilec Attic Insulation Is Failing
- Rooms directly under the attic run 5 to 8 degrees warmer than the rest of the house. This usually means the foam has shrunk or pulled away from the roofline, letting heat radiate down through the ceiling.
- Visible gaps or cracks in the foam surface. Demilec foam can separate from wood framing as the house settles, especially in San Antonio’s clay-heavy soil. Any daylight showing through a gap is a problem.
- A sudden jump in your cooling bill during a mild month. Foam that’s lost adhesion stops doing its job gradually, but the bill spike is often the first hard number homeowners notice.
- Musty or stale smell coming from the attic. Open-cell foam that’s been exposed to a roof leak soaks water like a sponge. That trapped moisture degrades the foam and invites mold.
- Cold spots on ceilings during winter. San Antonio attics don’t get much snow, but December nights drop into the 40s. Failed insulation shows up as uneven ceiling temperatures you can feel with your hand.
If you’re noticing one of these, it’s worth getting eyes in the attic sooner rather than later. A small delamination today becomes a full re-spray next summer if left alone.
Replacement Cost & What’s Included
In San Antonio, Demilec-compatible spray foam replacement runs $2.40 to $4.80 per board foot installed, which includes removing the failed material, surface prep, and the foam application itself. For a typical 1,500-square-foot attic needing partial or full re-spray, that works out to roughly $4,000 to $12,000 depending on depth and square footage. Blown-in fiberglass or cellulose to supplement existing foam runs lower, typically $1.50 to $3.00 per square foot installed, and often makes sense when the foam is still structurally sound but underperforming on R-value.
What drives the range: how much failed foam has to come out, whether it’s open- or closed-cell, attic access difficulty, and whether we’re adding baffles or air sealing along the way. Every quote includes the same things: a written price before any work begins, removal and disposal of failed material, the full installation, and a walkthrough with the technician when the job is done. The 365-Day Done Right Promise covers labor and materials for a full year, in writing. If the repair fails, we return and fix it free.
DIY or Call Us?
There are things you can safely do from the attic access hatch: look for visible gaps, take photos, check for water staining on the roof deck. That’s useful information and it helps us give you a better phone estimate. What you shouldn’t do is attempt to re-spray foam yourself. Two-component spray foam requires specialized equipment, proper respirator protection, and precise temperature and humidity control for the foam to cure correctly. Get the mix wrong and you’ve got a sticky, off-gassing mess that costs more to fix than the original problem.
The same goes for removing old foam. Scraping and pulling Demilec foam without understanding what’s structural versus cosmetic can damage the roof deck. If you’ve got a failed Demilec application in your San Antonio attic, call us at (361) 213-9499. We’ll send a technician who knows exactly what they’re looking at.
Common Questions About Demilec Insulation in San Antonio
How long does Demilec spray foam insulation last?
Demilec spray foam, when installed correctly and protected from moisture, typically lasts 30 to 50 years in a San Antonio attic. The failure we see most often isn’t the foam breaking down chemically, it’s installation problems from the start: improper mix ratios, spraying onto dirty or damp surfaces, or applying too thick in one pass. A roof leak will kill even the best-sprayed foam within a few seasons. If your foam failed early, the install is usually the culprit, not the product. Call (361) 213-9499 and we’ll tell you what we’re seeing.
Can failed Demilec foam be repaired instead of fully replaced?
Yes, in many cases. Small sections of delaminated or damaged foam can be cut out, the surface prepped, and new Demilec-compatible foam sprayed in to match. The key is patching with the same product type: open-cell over open-cell, closed-cell over closed-cell. Full replacement only makes sense when the foam has failed across more than about 30 percent of the attic surface or when there’s widespread moisture damage. We’ll show you the numbers both ways before you decide.
How long does a Demilec attic insulation replacement take?
Most Demilec replacement jobs in San Antonio take one to two days. Day one is removal and prep, day two is the re-spray. Smaller patches can be done in a single four-to-six-hour visit. You’ll get a schedule in writing before we start, and the tech that shows up is the same person whose name and photo we sent you in advance. If anyone else arrives, the visit is free and we make it right.
Do you stock Demilec insulation parts and materials locally?
We stock Demilec Heatlok HFO and Sealection 500 on our San Antonio trucks, along with aftermarket equivalents and blown-in options from Owens Corning, Johns Manville, Knauf, Rockwool, CertainTeed, Icynene, GreenFiber, and Reflectix for radiant barrier applications. That means most jobs go from diagnosis to installation without waiting on a supplier shipment. If you need something specific, call and ask; a live person answers 24/7.
If your attic’s cooking, your AC is drowning – let’s fix the cause, not just the bill.
Garrett Sloane grew up in Los Angeles and trained at Los Angeles Trade-Technical College before spending years on insulation crews across Southern California and the Southwest. He’s been running jobs in San Antonio for over a decade, from new construction near the Pearl District to retrofits in older homes that hadn’t seen an upgrade since the eighties. He runs Aspen Attic Insulation San Antonio under the Threshold Verified standard: background-checked, photo-badged technicians in marked uniforms, with your written price in hand before any tool comes off the truck.
Call (361) 213-9499 for a free estimate on your Demilec attic insulation repair or replacement. We answer the phone, we show up when we say, and the work is covered by the 365-Day Done Right Promise.
Written by Garrett Sloane, Owner, Aspen Attic Insulation San Antonio at Aspen Attic Insulation San Antonio, serving San Antonio and nearby areas.