Demilec Radiant Barrier Installation Nationwide

Demilec Radiant Barrier Installation: The Leander Owner’s Guide

Demilec radiant barrier installation in Leander typically runs $1,800-$3,400 for a standard 2,000-square-foot attic, and we stock Demilec-compatible rolls and tape on every truck for same-day starts. Most homeowners in Leander figure out something’s wrong when their upstairs bedrooms won’t cool below 78°F in July, or when their AC runs non-stop from 2 p.m. to sunset. The radiant barrier itself doesn’t “break” like a mechanical part, but it fails in place: torn sheets, dust-coated foil that quits reflecting, or gaps where a previous crew stapled it directly over unsealed top plates and called it done.

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Which Demilec Models This Applies To

Demilec doesn’t sell a standalone “radiant barrier system” under its own model numbers the way they catalog spray foam rigs. What you’re looking at is Demilec’s Heatlok HFO or Sealection 500 spray foam paired with a reflective foil component, or a retrofit where Demilec open-cell foam was applied to the roof deck and a radiant barrier was supposed to go beneath it or over it. The compatibility gotcha in Leander homes built 2015-2021: Demilec open-cell foam on the roof deck needs a vented air gap above it if you’re adding foil, or the assembly traps moisture and the foam delaminates. We’ve pulled down black-stained Demilec foam in Crystal Falls attics where a handyman stapled foil directly against it with zero gap.

To identify what you’ve got, check the spray-foam surface for a Demilec lot stamp (usually on the rim joist or a test strip). If the foil is original, it’ll be perforated or unperforated aluminum sheet, typically 1,000 square feet per roll, 48 inches wide. We stock both perforated (for attic floor applications, lets moisture pass) and unperforated (for roof deck, requires intentional venting). Aftermarket equivalents from Reflectix match Demilec’s emissivity spec (0.03-0.05) but vary in tear strength; we use OEM-grade foil on Demilec foam jobs because the warranty language gets picky about “compatible materials.”

Signs Your Demilec Radiant Barrier Installation Is Failing

• Upstairs rooms heat up by 3-5°F every afternoon while the AC runs flat-out. The foil has lost reflectivity from dust accumulation, or it was never installed with proper emissivity in the first place. In Leander, attics hit 140°F regularly in July; a radiant barrier that reads above 0.10 emissivity on our thermal meter is doing almost nothing.
• You see tears, gaps, or foil hanging in strips from the rafters. Staple fatigue from thermal cycling, or the original installer used a pneumatic staple gun set too deep and the foil ripped free. We find this most often in Sendera Ranch and Travisso, where builders used the cheapest stapling labor available in 2017-2019.
• Black staining or musty smell near the roof deck. Moisture trapped between Demilec foam and non-perforated foil with no air gap. This is the failure mode that destroys the foam, not just the barrier. We document this with FLIR and photos before touching anything.
• Energy bills jumped 20-40% compared to the same month last year. The barrier isn’t reflecting radiant heat, so your ductwork in the attic is soaking up 130°F+ air and your AC is fighting a battle it can’t win. We verify this with a blower-door test and duct blaster before quoting.
• Daylight visible through the attic where foil meets the top plate or around penetrations. The barrier was never sealed to the envelope. It’s like wearing a raincoat with the zipper down. We see this in nearly every pre-2020 Leander attic we open.

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Replacement Cost & What’s Included

What drives the range: attic square footage, accessibility (truss height, hatch size), whether we’re working around existing Demilec foam, and how much air sealing the previous crew skipped. Every quote includes the written scope, the written 365-Day Done Right Promise, and the Documented Photo Record. We don’t start until you have the price in writing. Haven Standard Clause 1.

DIY or Call Us?

You can safely check: whether your foil is perforated or not, whether you see daylight at seams, whether your attic has any air gap between foam and foil. Use a flashlight, not your hands. Don’t walk the joists unless you know the load path.

Where DIY goes wrong: working around Demilec spray foam without tearing it, creating the required air gap without compressing the foam, and stapling at the correct tension so thermal cycling doesn’t pull the fasteners. Also, Leander’s 2021 IRC amendments require specific fire-rated tape at seams in occupied attics; most homeowners don’t know to check the edition year. And if you’re on a roof deck with Demilec foam below, one misplaced staple tears the foam skin and you’ve got an open-cell sponge that’ll hold moisture.

We carry Demilec-compatible foil, the right staples, the fire-rated tape, and the blower-door gear to prove the result. Call (737) 252-7159 for a free estimate. We’ll read your existing setup with you, no pressure.

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