Demilec Radiant Barrier Installation: The San Antonio Owner’s Guide
We stock and install Demilec-compatible radiant barrier materials across San Antonio, with most attic installations running $0.75 to $1.50 per square foot installed, depending on attic accessibility and the specific Demilec product you’re matching. We carry the material on our trucks, so most jobs get done the same day we show up. Here’s how this usually starts: a homeowner in Alamo Heights or Stone Oak notices their August electric bill jumped $80 over last year, goes up into the attic, and finds the radiant barrier sagging from the rafters or torn along a seam where the Texas heat finally got to it.
The failure is rarely the Demilec material itself. It’s almost always the fastening system or an installation shortcut from the original job. That’s the part most people don’t see until it’s too late.
Which Demilec Models This Applies To
Demilec produces radiant barrier products under a few different lines, and the compatibility question matters more than most contractors admit. The main ones we see in San Antonio attics are the Demilec HeatBloc series and their foil-faced polypropylene radiant barriers, which typically come in 4-foot and 6-foot wide rolls. The key spec that trips people up is the perforation pattern. Demilec radiant barriers are micro-perforated to allow moisture vapor to pass through, which prevents condensation from trapping against the roof decking. A non-perforated barrier installed in a San Antonio attic will trap humidity. That’s a mold invitation in a city where the summer dew point sits in the low 70s.
If you still have the roll label, look for the Demilec product code. If the label’s gone, measure the width and check whether the surface has tiny pinholes when held up to a light. That tells us which stock to pull from the truck. We can match Demilec with Demilec, or we can install a quality equivalent like Reflectix if the specific Demilec line has been discontinued. We’ll show you the difference and the price for each before anything goes up.
Signs Your Demilec Radiant Barrier Installation Is Failing
- Sagging or drooping between rafters. This is the number one failure we see in San Antonio, especially in homes built before 2010. The original installer used staples with too narrow a crown, and the weight of the foil plus a decade of attic heat cycles pulls them loose. Once the barrier sags more than a few inches, it loses most of its reflective ability.
- Torn seams at roof transitions. The valley where a roof pitch changes puts stress on the barrier. In San Antonio’s temperature swings, the roof decking expands and contracts enough to tear foil at the seam line. It’s a small tear that grows every summer.
- Noticeably hotter second floor or bonus room. Radiant barrier failure isn’t subtle in a Texas July. When a room above the garage starts running 8 to 10 degrees warmer than the rest of the house, the barrier above it likely failed.
- Condensation stains on roof decking. If you climb up and see dark streaks or signs of moisture on the underside of the roof, a non-perforated barrier may have been installed, or the perforations are blocked by dust. That trapped moisture is exactly what Demilec’s perforation spec is designed to prevent.
- Flapping or rustling in windy conditions. You’ll hear it before you see it during a San Antonio storm front. If the barrier is moving with the air currents, the fasteners have failed. A properly installed radiant barrier doesn’t move.
Replacement Cost & What’s Included
In San Antonio, Demilec radiant barrier replacement and installation runs roughly $0.75 to $1.50 per square foot installed. For a typical 1,800 square foot attic, that lands between $1,100 and $2,200. The price depends on three things: attic height and accessibility (low-pitch roofs cost more because they’re slower to work in), whether we’re doing a full replacement or a partial repair, and whether existing insulation needs to be moved or protected during installation.
Every quote includes the cost of materials, full labor, cleanup, and our written guarantee on the installation. We are an independent contractor, not affiliated with Demilec, so the material warranty comes from Demilec while the installation workmanship is covered by our 365-Day Done Right Promise. If it’s not right in the first year, we make it right. In writing, on every job.
There’s no price-at-the-door routine with us. The written number you get before we start is the number you pay. That’s how Chase Whitaker has run every job since he started doing attic work nearly two decades ago, and it’s not changing now.
DIY or Call Us?
Here’s what you can safely check yourself before making a call. Look at your radiant barrier from the attic access point with a flashlight. Check for sagging, tears, and whether the material is moving. You can also note the width of the existing barrier and whether it’s perforated. That information helps us quote accurately over the phone.
What you shouldn’t do is crawl out across attic joists to inspect or attempt a repair on a pitched roof section. A fall through a ceiling is a serious injury, and working near roof decking in a San Antonio attic in August means surface temperatures above 140 degrees. Heat-related illness hits fast up there. If your barrier is failing, call us at (254) 279-0971. A technician will inspect it, take photos, and give you a written price before any work starts.
FAQs
How long does a Demilec radiant barrier last in San Antonio? Demilec radiant barrier material itself is rated to last 20 to 25 years, but the fastening system typically fails after 10 to 15 years in San Antonio’s temperature extremes. The material outlasts the staples. When we reinstall, we use heavy-crown staples and additional fastening points to extend the effective life closer to the material’s full rating.
Can my existing Demilec radiant barrier be repaired instead of replaced? Yes, if the damage is limited to a defined area like a single valley tear or a section of sagging, repair makes sense. If the barrier is failing across multiple sections or moving with air currents through the whole attic, replacement is the honest recommendation. We’ll tell you which one you need, and the repair quote is always cheaper. Call (254) 279-0971 and describe what you’re seeing, and we’ll give you a straight read.
How long does the installation take? A typical San Antonio attic radiant barrier installation takes 4 to 6 hours for a single-story home with standard attic access. Two-story homes with more complex rooflines run 6 to 8 hours. We do most jobs in a single day, and our technicians arrive at a live, trackable time. You’ll see exactly when we’re pulling up.
Do you actually stock Demilec radiant barrier material? Yes. We carry Demilec-compatible radiant barrier rolls on our trucks, along with Reflectix as an equivalent option. Most jobs are completed the same day we arrive because the material is already there. If you need a specific Demilec line that isn’t on the truck, we can typically have it within a few days. Estimates are free, so call us for a firm number.
A comfortable attic isn’t a luxury in San Antonio – it’s just a house that works the way it should. If your Demilec radiant barrier has failed, the fix is straightforward. Call (254) 279-0971 for a free estimate and a written price before anything starts. Laurel Attic Insulation San Antonio serves the entire San Antonio area, from the Pearl District to Alamo Heights and everywhere in between.
Written by Chase Whitaker, Owner, Laurel Attic Insulation San Antonio at Laurel Attic Insulation San Antonio, serving San Antonio and nearby areas.