Demilec Attic Air Sealing Nationwide

Demilec Attic Air Sealing: The Pomona Owner’s Guide

We stock and install Demilec-compatible attic air sealing components for Pomona homes, with most repairs running $340-$780 installed depending on attic square footage and how many top-plate penetrations need sealing. Same-day service is available when we have your model specs by phone. Most homeowners in Pomona discover a problem when their summer AC runs constantly but the upstairs bedrooms never cool below 78 degrees, or when they spot dusty fiberglass batting around recessed can lights - a telltale sign that conditioned air is escaping through bypasses the Demilec seal was meant to block.

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Which Demilec Models This Applies To

Demilec’s attic air sealing line breaks into two series that matter for part matching: the Heatlok HFO Pro line, common in 2018-2022 Title 24 compliance jobs across Los Angeles County, and the older Sealection 500 formulations found in retrofits from the early 2010s. The HFO Pro series uses a higher-density closed-cell foam - 2.0 lbs/ft³ versus 0.5 lbs for open-cell - and if your original installer used it around top plates, you’ll need the same density to maintain the fire rating and prevent thermal drift.

Check the spray-foam tag left on your attic rafter or the documentation from your original job. No tag? Measure the cured foam thickness at a penetration: HFO Pro finishes at 2-3 inches for air sealing, while open-cell Demilec expands past 3.5 inches and feels spongy to the touch. We carry both OEM Demilec cartridges and equivalent-density aftermarket foams from Icynene and Johns Manville that meet the same ASTM E84 Class A rating. For Pomona’s hot-dry climate, we generally recommend staying with closed-cell at top plates; open-cell can degrade faster when attic temperatures spike past 140°F in August, which they do regularly in neighborhoods below the 57 Freeway corridor.

Topside Attic Insulation Pomona is an independent service provider - we’re not affiliated with Demilec - and we source materials from multiple manufacturers so we can match your existing chemistry rather than forcing a full tear-out.

Signs Your Demilec Attic Air Sealing Is Failing

• Hot second-floor rooms despite new insulation. The R-value on your attic floor is performing, but conditioned air is leaking around it through failed seals at top plates and wire penetrations. We see this most in Pomona’s 1960s-1970s ranch homes near Ganesha Park, where original construction left gaps the Demilec was retrofit to close.
• Dust streaks on attic-side drywall around light fixtures. These are thermal bypass tracks - air moving through unsealed gaps carries attic dust into the conditioned space. If your recessed cans have dark halos, the Demilec seal around the housing has pulled away or shrunk.
• Ice damming or moisture staining at ceiling edges in winter. Even in Pomona’s mild winters, a failed air seal lets warm moist air hit cold roof sheathing. The Demilec was likely applied as a vapor barrier as well; once compromised, condensation follows.
• Spongy or crumbling foam visible at attic penetrations. UV exposure from gable vents or degraded batch chemistry can cause open-cell Demilec to powder after 8-12 years. Closed-cell HFO Pro lasts longer but can delaminate from OSB if the substrate wasn’t primed.
• Blower-door test showing minimal improvement after “insulation upgrade.” A common scenario: a Pomona homeowner pays for blown-in fiberglass over old Demilec seals, and the CFM50 reading barely moves. The insulation buried the leaks instead of sealing them.

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After

Replacement Cost & What’s Included

Most Demilec attic air sealing jobs in Pomona run $340-$780 for a typical 1,200-2,000 square foot home, scaling to $1,100-$1,600 for larger homes with complex rooflines or multiple HVAC zones. The lower end covers spot repairs - resealing 8-12 top-plate penetrations and 4-6 recessed can housings. The upper end involves full attic-floor air sealing with dense-pack treatment at all electrical and plumbing chases, plus a post-job blower-door test.

Every quote we write includes: material (OEM Demilec or matched-density equivalent), labor, cleanup, and our Documented Photo Record. We also publish before-and-after blower-door numbers on every applicable job - a pressurization reading that shows, in one number, how much air your building envelope was losing before and after the work. Under Haven Standard Clause 1, you get that written price before anyone lifts a tool, plus a written scope and warranty. The 365-Day Done Right Promise covers all completed work.

DIY or Call Us?

There’s a short list of checks any Pomona homeowner can make safely: confirm your attic access is stable, photograph any visible foam degradation, and note which rooms never hold temperature. What you shouldn’t do is attempt to re-apply spray foam yourself. Two-part polyurethane requires respirator-rated PPE, precise substrate temperature control (above 60°F and rising, which winter mornings in Pomona often aren’t), and proper ignition barrier coverage per California Title 24. Misapplied foam off-gasses, creates fire hazards, and voids your home insurance if documented improperly.

We carry Demilec-compatible foam on the truck, run the blower-door test before any material goes in, and seal the leaks first. The insulation is just the last layer of the answer. Call (562) 242-7569 for a written price - estimates are free, and we deliver a Free Second Opinion on any competing quote you bring us.

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