Demilec Radiant Barrier Installation Nationwide

Demilec Radiant Barrier Installation: The New Braunfels Owner’s Guide

Demilec radiant barrier installation in New Braunfels typically runs $1,800-$3,400 for a standard 1,800-2,400 square foot attic, and we stock Demilec-compatible materials on every truck for same-day starts when the attic access is clear. Most homeowners realize something’s off when their summer electric bills spike 20-40% above the previous year despite the thermostat never moving, or when they climb into the attic in July and the air feels nearly as hot as the roof deck itself. The radiant barrier, a reflective foil layer installed beneath the roof decking or draped over rafters, has either detached, oxidized, or was never properly sealed at the perimeter to begin with.

Call (830) 243-6352

Which Demilec Models This Applies To

Demilec doesn’t sell a standalone “radiant barrier” product line under its own brand name. Instead, Demilec (now part of Huntsman Building Solutions) manufactures open-cell and closed-cell spray foam systems, notably the Heatlok HFO Pro and Sealection 500 lines, that are frequently paired with third-party radiant barriers in hybrid attic assemblies across New Braunfels and the I-35 corridor. What you’re likely looking at is a radiant barrier that was installed alongside Demilec foam, or a retrofit where the existing barrier needs replacement without disturbing the Demilec layer beneath.

To identify what you’ve got, check the attic for a foil-faced product stamped with ASTM C1313 or ASTM C1224 markings, and note whether it’s stapled to the rafters (draped method), laminated to the roof deck (foil-faced OSB), or a loose “over-batten” install. The critical compatibility gotcha in Central Texas: Demilec closed-cell foam expands to roughly 3.5-4.0 lbs per cubic foot density, and if your radiant barrier was installed directly against the foam without a proper air gap, the foil surface can delaminate where it contacts the cured resin. We see this most often in Canyon Lake-area homes built 2012-2018, where builders rushed the hybrid assembly. OEM radiant barrier from the original installer is rarely necessary; we source equivalent ASTM-rated foil from Reflectix and other suppliers that matches the emissivity spec without the proprietary markup.

Signs Your Demilec Radiant Barrier Installation Is Failing

• Summer AC runs constantly but never catches up. The radiant barrier’s job is to reflect infrared heat back toward the roof deck before it radiates into the attic space. When the foil oxidizes, tears, or pulls away from the fasteners, attic air temperatures can climb from a managed 110°F to 140°F or higher. Your ductwork, especially if it’s flex running through the attic, is now sitting in a convection oven.
• Visible tears, sagging, or missing sections in the foil. New Braunfels attic heat cycles from 40°F winter nights to 140°F summer days create expansion and contraction that pop staples loose. We find whole sheets draped over insulation in older Solms and Gruene neighborhoods, where original installs used 1/4″ crown staples instead of the wider 3/8″ fasteners that handle thermal movement better.
• Hot spots on your ceiling during afternoon hours. This usually means the barrier was never continuous, or gaps at the ridge and eaves are letting radiant heat through in bands. In slab homes near the River Road corridor, we’ve measured 15-20°F surface temperature differences between ceiling areas that were covered and those that weren’t.
• Moisture staining on the foil or roof deck. A radiant barrier installed without proper attic ventilation can trap humidity, especially in spring when Gulf moisture rolls up the I-35 corridor. Demilec foam is vapor-impermeable when closed-cell; pair that with a sealed attic and a compromised barrier, and you’ve got condensation collecting where the foil meets the rafter bay.
• Your home was built 2010-2017 and the barrier was “builder grade.” The foil installed in that era was often the lightest-weight product that met code minimum, with emissivity ratings barely below 0.05. After 8-10 Texas summers, that material degrades measurably. We’ve pulled foil in New Braunfels attics that tested at 0.15 emissivity, effectively doing nothing.

Before

After

Replacement Cost & What’s Included

Most Demilec-associated radiant barrier replacements in New Braunfels fall between $1,800 and $3,400 installed, with the spread driven by three factors: attic square footage, whether we need to work around existing Demilec foam without damaging it, and whether the original install included perimeter sealing that we now have to correct. A straightforward 2,000-square-foot attic with clear rafter access and intact foam runs toward the lower end. Jobs where we’re cutting and fitting around existing spray foam, or replacing foil-faced OSB panels from the roof-deck side, push toward the upper range.

Our price includes the ASTM-rated replacement barrier material, all fasteners and tape rated for high-temperature attic use, perimeter sealing at ridge and eaves, and a post-install blower-door test if we’re also touching the air-sealing package. We don’t start work without a written price, and we don’t finish without a Documented Photo Record of the completed barrier layout. The 365-Day Done Right Promise covers labor and material defects; manufacturer warranty on the foil itself runs 10 years against delamination and emissivity degradation.

DIY or Call Us?

There’s nothing inherently dangerous about radiant barrier material, it’s just foil, but the attic environment in a New Braunfels July is a legitimate hazard. Heat stress and dehydration send more homeowners to urgent care than any tool injury. If you’re determined to inspect yourself, check the attic early morning, bring water, and look for the symptoms above without touching electrical or the Demilec foam surface.

Where DIY goes wrong is in the details that determine whether the barrier actually works: maintaining the critical 3/4″ minimum air gap between foil and roof deck, sealing the perimeter to prevent convective looping, and not compressing existing insulation while maneuvering in tight quarters. We’ve been called to fix homeowner installs where the foil looked fine but was doing nothing because it was laid directly on the attic floor, reflecting heat back into the living space. If your attic has Demilec foam in the assembly, disturbing that cured surface can create voids that compromise the envelope. For a written price on proper replacement, call (830) 243-6352. Estimates are free, and we stock the material.

FAQs