Demilec Attic Air Sealing Nationwide

Demilec Attic Air Sealing: The Pomona Owner’s Guide

Demilec attic air sealing is a closed-cell spray foam application used to seal the attic floor plane, penetrations, and bypasses that let conditioned air escape and outside air creep in. In Pomona, an installed attic air sealing package using Demilec-compatible foam typically runs $1,800 to $3,600 depending on attic square footage, access difficulty, and how many penetrations need treatment. Most Pomona homes can have the job done in a single day, and most of our trucks already carry what’s needed. Homeowners usually find us because a previous sealing job has failed, a specific area has started leaking air again, or they’re about to sell a house and need a clean, documented air seal.

Call (626) 341-0830

Which Demilec Models This Applies To

The core requirement is Demilec’s closed-cell line: Sealection 500, Heatlok HFO High Lift, and Heatlok Soy 200 Plus are the most common in Pomona attics. These are two-component spray foams that expand and cure in place, forming an air-impermeable barrier. The most useful thing to know is this: Demilec products are part of a manufacturer-specified system, and the two components – isocyanate and polyol resin – must come from the same lot or a manufacturer-verified source. Mixing a random drum of “B-side” with a Demilec A-side is the single fastest way to end up with foam that won’t cure, off-gasses, or fails within weeks. If you’re sourcing product yourself, check that the batch numbers trace back to Demilec; if you’re not sure, let us handle it. Warmline Insulation Co. is an independent service provider and not affiliated with Demilec, but we’re familiar with their product line and install to their spec.

Signs Your Demilec Attic Air Sealing Is Failing

• Unexplained spike in cooling or heating costs: Demilec foam that’s curing properly should seal for years. When a section cracks, pulls away from the roof deck, or was never adherent to begin with, conditioned air leaks out and Pomona’s July heat pours in.
• Dust or fiberglass particles appearing inside the house: A failed air seal opens the attic floor plane, letting loose-fill insulation, dust, and whatever’s been tracked through the attic drop into living spaces through light fixtures and can lights.
• Cold drafts near attic hatch or pull-down stairs in winter: The attic access door is a notorious leak point. If the Demilec bead around the hatch frame has separated, you’ll feel it stand on a ladder below the access.
• Unusual pest activity or rodent droppings in the attic: Closed-cell foam doesn’t repel rodents, but properly sealed penetrations eliminate the gaps they use. A hole in the seal around a plumbing vent is a welcome sign for rats.
• Uneven room temperatures upstairs: In Pomona houses built before about 1990, the attic floor often has no continuous air barrier. Once Demilec has been applied, a failing section reopens the bypasses that cause hot bedrooms over the garage.

Replacement Cost & What’s Included

In Pomona, plan on $1,800 to $3,600 for a full attic air sealing replacement using Demilec-compatible closed-cell foam. That includes a pre-inspection, masking off vents and fixtures, applying the foam at the recommended lifts, trimming and cleanup, and a post-job visual verification with photos. The range depends mostly on attic size: a 1,200-square-foot attic runs toward the lower end, while a 2,000-plus-square-foot attic with multiple plumbing vents, recessed lights, and a finished bonus room pushes toward the upper end. You’re also paying for a crew that knows how Demilec behaves in Pomona’s dry, hot climate – foam that’s applied too thick in high heat can over-expand and crack. Every job includes our 90-Day Done Right Promise: if the work isn’t right, we make it right. No hidden line items.

DIY or Call Us?

You can safely check the visual condition of your Demilec foam by looking for cracks, separation from framing, or areas where the foam looks dark or discolored. That’s the extent of what we recommend without professional equipment. Spray foam application involves heated hoses, exact ratio mixing, and respiratory protection – and if the ratio is off or the substrate is too hot, the foam fails or off-gasses. Demilec’s own safety data sheets require full face protection and fresh air supply during application. If you already have a failed section, we’ll match the existing foam and re-seal the area cleanly. Call (626) 341-0830 and a live person answers – always, any hour. We’ll tell you if the job is worth doing at all before you spend a dollar.

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