Demilec Attic Air Sealing Nationwide

Demilec Attic Air Sealing: The Leander Owner’s Guide

We stock and install Demilec-compatible attic air sealing components in Leander, with most repair and replacement jobs running between $340 and $780 installed depending on attic square footage and how many top plates, can light housings, and penetration boots need resealing. Same-day service is available when the failure is active - a sudden spike in your summer electric bill or visible daylight through the attic floor usually means conditioned air is dumping into the roof deck. In Leander’s climate, where attic temperatures push past 140°F from June through September, a compromised Demilec air seal doesn’t gradually fail; it accelerates your insulation’s irrelevance.

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Which Demilec Models This Applies To

Demilec’s attic air sealing line spans several product families, and the part you need depends on what was originally applied. The SEALECTION 500 open-cell spray foam kits, common in Leander builds from 2015 to 2021, use a 2.0 lb density foam that shrinks differentially across top plates in our dry heat; the HEATLOK SOY 200 series, a closed-cell alternative, is more dimensionally stable but was often sprayed too thin over electrical penetrations in production homes. To identify your application, look for the Demilec batch tag on any exposed foam surface - usually a yellow or white sticker with a 10-digit lot number and density rating. If the tag is gone, measure the cured foam thickness with a pick: SEALECTION cures to roughly 3.5 inches in a single pass, HEATLOK SOY to 2 inches.

We do not source proprietary Demilec factory parts because Demilec sells bulk chemical systems, not discrete “parts” in the traditional sense. What we stock are OEM-spec replacement foams and compatible mechanical sealing components - backer rod, acoustical sealant, and fire-rated caulk for penetrations - matched to the original density and ASTM E-84 flame spread rating. For homeowners in Crystal Falls and Travisso who had Demilec applied during original construction, this means we can patch or rebuild the seal layer without tearing out functional insulation above it. Topside Attic Insulation Leander is an independent service provider, not affiliated with Demilec.

Signs Your Demilec Attic Air Sealing Is Failing

• Electric bills jump 20% or more in July and August with no thermostat change. The air seal was doing more work than the insulation itself in Leander’s climate; when it cracks or pulls away from top plates, your HVAC replaces that lost conditioned air continuously. We see this pattern most often in homes built 2017 to 2020 where SEALECTION was applied over dusty framing.
• Hot spots on your ceiling visible to the touch or on a FLIR camera. These track directly to unsealed can light housings or bath fan boots where the Demilec foam separated from the drywall. The thermal bypass is predictable: air moves through the gap, heats the drywall from behind, and creates a rectangle of warmth your hand can find.
• Dust accumulation around ceiling registers or return grilles. This is attic air being pulled into your living space through leaks that bypass the filter. In Leander’s windy spring months, unsealed attic floors act as particulate pumps.
• Ice damming or persistent frost in the attic during rare hard freezes. Warm, moist interior air leaking through a failed seal condenses on cold roof sheathing. It’s uncommon here, but the 2021 freeze revealed how many Leander attics had lost their air barrier integrity.
• Visible cracks or shrinkage in exposed foam at the attic hatch or knee walls. Demilec open-cell foams can shrink 3-5% over time in low humidity; in Leander, that’s most of the year. The foam itself may still be intact, but the gap at the substrate is the failure point.

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Replacement Cost & What’s Included

Most Demilec attic air sealing repairs in Leander fall between $340 and $780 installed. The low end covers localized failure - a dozen can light housings, a bath fan boot, perimeter top plate gaps in a 1,500 square foot attic. The high end applies to full resealing of a 2,500+ square foot attic where the original application has degraded across multiple penetration types.

Every job includes the written price before work starts - Haven Standard Clause 1 - and closes with a Documented Photo Record. Where applicable, we provide before-and-after blower-door readings so you can verify the air-sealing result in CFM50, not promises. The 365-Day Done Right Promise covers all completed work. Materials are sourced from Demilec-compatible specifications; we also stock Reflectix components where radiant barrier integration is part of the repair.

DIY or Call Us?

There’s a short, honest list of what a Leander homeowner can safely check: confirm the attic hatch gasket is intact, verify bath fan dampers close fully, and look for obvious daylight through the attic floor from below. Do not attempt to spray or cut foam yourself. Demilec’s two-component systems require respiratory protection beyond a hardware-store mask, and the exothermic reaction during application can ignite surrounding materials if the mix ratio is wrong. More critically, resealing an attic floor without blower-door guidance means you’re guessing at pressure boundaries; we’ve found homeowners who sealed the wrong side of the top plate and trapped moisture in the wall cavity.

If your electric bill has spiked or you’ve found visible gaps, call (737) 252-7159. We’ll read your situation with you - no charge for the conversation - and if you have a competing estimate, we provide a Free Second Opinion on any written quote.

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