Demilec Radiant Barrier Installation: The San Antonio Owner’s Guide
Demilec radiant barrier installation in San Antonio typically runs $1.45 to $2.60 per square foot installed, with most single-story homes landing between $2,100 and $4,800 depending on attic size and access. We stock Demilec-compatible radiant barrier material on our trucks and can usually complete a full attic install in one day. Homeowners most often call us because their existing barrier has torn away from the rafters, is sagging, or was never installed correctly in the first place.
The reality in San Antonio is that radiant barrier takes a beating. Attic temperatures here routinely hit 140°F in July and August, and the temperature swings between day and night cause staples to back out and seams to separate. If you’re seeing higher cooling bills this summer than last, or your upstairs rooms won’t hold temperature, your radiant barrier may have failed. That’s the call we get most often.
Key takeaways:
- We install Demilec-compatible radiant barrier across San Antonio, from Alamo Heights to Helotes to Stone Oak.
- Same-day installation is available on most single-story homes with standard attic access.
- Every job gets a written price before we start. No surprises after.
- Your tech’s name and photo are sent to you before the appointment. That’s the Threshold Standard.
Which Demilec Models This Applies To
Demilec doesn’t make radiant barrier as a standalone consumer product the way they make spray foam. What most San Antonio homeowners have is a Demilec spray foam insulation system combined with a separate radiant barrier layer, often a foil-faced product installed under the roof deck. The distinction matters because the radiant barrier layer is what fails first in Texas heat, while the Demilec foam underneath often remains intact.
If you have Demilec Heatlok HFO or Demilec Sealection 500 in your attic, the radiant barrier was likely installed as a foil laminate either stapled to the rafters or laid over the attic floor joists. The foil layer can be Reflectix, Double Bubble, or an attic-foil product, but the failure mode is the same: the foil delaminates, the staples pull loose, or dust and oxidation reduce reflectivity. When you call us, we’ll identify what’s actually on your attic floor and rafters, verify whether your Demilec foam is still performing, and match the radiant barrier to your setup rather than selling you something you don’t need.
One compatibility detail most homeowners never learn: radiant barrier stapled to the underside of roof decking needs an air gap to work. Foil pressed directly against the roof sheathing conducts heat instead of reflecting it. We see this mistake in San Antonio attics constantly, and it’s the first thing Garrett Sloane looks for when we walk an attic.
Signs Your Demilec Radiant Barrier Installation Is Failing
- Your upstairs rooms won’t cool below 80°F in the afternoon. When radiant barrier fails, the attic turns into a heat sink and that heat pushes down through the ceiling insulation. Your AC works harder just to hold a temperature it used to reach easily.
- Cooling bills jumped 20-30% with no change in usage. Radiant barrier reduces heat gain before it reaches your insulation. When it’s gone, your AC picks up the full load. That cost shows up fast in summer months.
- You can see shiny foil sagging or hanging from the rafters. If you can see it from the attic access, it’s already failed. Properly installed radiant barrier should be taught against the roof deck with no droop.
- The attic feels hotter than it should even at dusk. Radiant barrier reflects heat away from the attic space. When it’s working, the attic cools down noticeably after the sun drops. If it’s still roasting at 9 PM, the barrier isn’t doing its job.
- Dust has coated the foil surface. Radiant barrier works by reflecting radiant heat. Dust acts like a blanket, killing reflectivity. San Antonio’s dry climate means dust accumulates fast, especially in attics with open eave vents.
If your attic’s cooking, your AC is drowning – let’s fix the cause, not just the bill.
Replacement Cost & What’s Included
Radiant barrier replacement in San Antonio typically runs $1.45 to $2.60 per square foot installed, with the final price driven by attic height, roof pitch, existing insulation condition, and whether we’re removing failed material or installing over an empty attic floor. A 1,500 square foot attic usually lands between $2,100 and $3,900. A 2,500 square foot attic typically runs $3,600 to $6,500.
Here’s the breakdown in San Antonio:
| Scope | Typical Range |
|---|---|
| Attic floor radiant barrier (1,500 sq ft) | $2,100 – $3,900 |
| Under-roof deck installation (1,500 sq ft) | $2,600 – $4,500 |
| Failed material removal + disposal | $300 – $750 |
| Full attic, 2,500 sq ft | $3,600 – $6,500 |
Every job includes a written price before work starts, removal of failed material, and our 365-Day Done Right Promise in writing. If the installation fails within a year, we come back for free. That covers labor and materials, no fine print.
We don’t use one-size-fits-all pricing. Your quote depends on what’s actually in your attic, not on a square-footage formula from a call center. Garrett walks the space himself before we write anything up.
DIY or Call Us?
You can safely check a few things yourself: look for sagging foil, visible tears, or areas where the barrier has pulled away from staples. That’ll tell you whether you have a problem. What you shouldn’t do is climb into a San Antonio attic in July to re-staple foil across roof rafters. Attics here hit 140°F and up, which is dangerous for anyone without proper ventilation and hydration protocol, and the roof decking isn’t built to be walked on. A fall through a drywall ceiling is a hospital trip, not a weekend project.
Even in cooler months, most failed radiant barrier needs replacement, not repair. Foil that’s torn, dust-coated, or delaminated doesn’t reflect heat anymore. Re-stapling it just secures a product that’s already lost its reflectivity. If we install it, you get a written price, a photo-badged tech whose name you know before the door opens, and a full year of coverage on the work. Call (361) 213-9499 if you want us to take a look.
FAQs
Radiant barrier in San Antonio attics typically lasts 15 to 25 years, but dust accumulation and staple failure can cut that short in as little as 7 to 10 years if the original install was sloppy or the attic has heavy eave ventilation. The barrier itself doesn’t wear out, but its reflectivity drops as dust coats it. Call (361) 213-9499 for an exact quote on replacement, estimates are free.
In most cases, no. Torn or sagging radiant barrier has already lost the air gap or the reflectivity that makes it work, so repair is just delaying replacement. If the damage is isolated to a small section, we can patch it, but we’ll tell you honestly if replacement is the better long-term call. Call us at (361) 213-9499 and we’ll walk your attic and give you a straight answer.
Most Demilec-compatible radiant barrier installations in San Antonio take one full day, with larger or two-story homes running into a second morning. We’ll tell you the exact timeline when we give you your written price, and your tech’s name and photo are sent to you before the visit.
Yes. We keep Demilec-compatible radiant barrier material in stock along with Reflectix and other brands, so we can start the same day in most cases. If you call before noon, there’s a good chance we can complete the job by evening.
Written by Garrett Sloane, Owner, Aspen Attic Insulation San Antonio at Aspen Attic Insulation San Antonio, serving San Antonio and nearby areas.