Demilec Attic Air Sealing Nationwide

Demilec Attic Air Sealing: The Tustin Owner’s Guide

We stock and install Demilec-compatible attic air sealing components for Tustin homes, with most completed jobs running between $1,800 and $3,400 depending on attic square footage and penetration count. Same-day service is available when we have your configuration in stock, which covers the majority of Demilec open-cell and closed-cell foam systems installed in Orange County between 2012 and 2022. Most Tustin owners discover their Demilec air sealing has failed when their upstairs rooms won’t hold temperature despite the AC running continuously, or when a home energy audit reveals attic-floor leakage above 2,000 CFM50 after the original foam has pulled away from top plates or shrunk around can-light penetrations.

Call (657) 286-7673

Which Demilec Models This Applies To

Demilec’s product line for residential attic air sealing breaks into two eras that matter for parts compatibility. Pre-2018 systems were largely open-cell SEALECTION 500 or AgriThane 7310, identifiable by the cream-colored foam and a density around 0.5 pounds per cubic foot. Post-2018, Demilec shifted toward higher-density closed-cell products like Heatlok HFO Pro, which runs gray to light yellow and weighs in at roughly 2.0 pounds per cubic foot. The critical compatibility gotcha: these two eras use different expansion ratios and surface-preparation protocols, so patching a 2015 SEALECTION job with 2024 Heatlok material creates a thermal bridge at the seam that blower-door testing will catch every time.

To identify what’s on your attic floor, check the spray-foam applicator tag left by the original installer, usually stapled to a rafter or the attic access hatch. If that’s missing, we measure foam density with a simple core sample and check adhesion to the substrate. Demilec OEM foam is what we default to for warranty continuity, though we also carry Johns Manville and Icynene equivalents that meet the same ASTM E84 Class A fire rating and California Energy Code R-value requirements. Topside Attic Insulation Tustin is an independent service provider, not affiliated with Demilec. We do not recommend aftermarket foam for Demilec systems still under the original 10-year material warranty, as that voids coverage.

Signs Your Demilec Attic Air Sealing Is Failing

• Uneven temperatures between floors. The upstairs runs 8 to 12 degrees warmer in July because conditioned air is escaping through gaps in the attic floor faster than your HVAC can replace it. We see this pattern consistently in Tustin Legacy homes where the original Demilec application missed the top plate at the wall-to-ceiling junction.
• Dust accumulation around recessed can lights. Those dark rings on your ceiling paint are filtration soiling, airborne particles passing through a gap that the foam was supposed to seal. In Tustin’s Santa Ana wind patterns, attic pressure changes seasonally and pulls conditioned air outward through any penetration that has delaminated.
• Spiking summer electric bills with no rate change. A Demilec system that was performing at 1,800 CFM50 when installed and now reads 3,400 CFM50 is leaking roughly twice the conditioned air. Your compressor runs longer to compensate, and the kilowatt-hours show it.
• Visible shrinkage or cracking in attic foam. Open-cell Demilec can shrink 5 to 10 percent over the first five years if the substrate wasn’t properly conditioned, leaving hairline cracks at stud bays and around duct boots. Closed-cell is more dimensionally stable but can pull away from oily or dusty surfaces.
• Ice damming or moisture staining in winter months. Even in Tustin’s mild climate, rare cold snaps can create condensation at air-leak points where warm interior air meets cold attic sheathing. The foam was your vapor retarder and air barrier combined; when it fails, both functions fail.

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Replacement Cost & What’s Included

Most Demilec attic air sealing replacements in Tustin fall between $1,800 and $3,400 installed. The low end covers a targeted repair: 800 to 1,200 square feet of attic floor, addressing the typical failure points around top plates, can lights, and plumbing penetrations with Demilec-compatible foam. The high end applies to full removal and reapplication when the original foam has degraded across the entire attic, or when we find that insulation was blown over unsealed gaps and both layers need correction.

What drives the range: attic accessibility (scissor truss vs. conventional), square footage, penetration density, and whether we’re working around existing blown-in fiberglass that must be temporarily removed and replaced. Every job includes the written scope and written warranty before anyone starts, per Haven Standard Clause 1. We also publish before-and-after blower-door numbers on every applicable job, so you’ll see your CFM50 reduction in black and white. The 365-Day Done Right Promise covers all completed work. Call (657) 286-7673 for a written price on your specific configuration.

DIY or Call Us?

There’s a short list of what a Tustin homeowner can safely check without tools: verify your attic access path is clear, photograph any visible foam damage for our review, and note the model numbers on your HVAC equipment if the foam is near ductwork. What you should not attempt is purchasing two-part spray foam from a hardware store and applying it yourself. Demilec and equivalent professional foams require controlled temperature, precise substrate moisture content, and respiratory protection beyond standard dust masks. The exothermic reaction during application can reach 200 degrees Fahrenheit, and improper mixing yields foam that looks correct but fails adhesion testing within months.

More critically, attic air sealing is only half the diagnostic. Without a blower-door test, you’re guessing at which leaks matter most. We pressurize the house, use theatrical smoke to trace leakage paths, then seal in priority order. The R-value on the bag means nothing if conditioned air is moving through the gap around that recessed can. For documented results and a written price before any work starts, call (657) 286-7673.

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