Demilec Attic Air Sealing Nationwide

Demilec Attic Air Sealing: The Los Angeles Owner’s Guide

If your Demilec spray foam attic air seal is failing, we stock Demilec-compatible sealing materials on our trucks and can handle most Los Angeles attic air sealing repairs same-day. A typical Demilec attic air sealing repair or reinforcement in Los Angeles runs $950 to $3,400 installed depending on attic size, accessibility, and how much of the existing seal has degraded. Most homeowners discover the problem the hard way: a bedroom that won’t hold temperature in August, a utility bill that creeps up month after month, or dust and pests finding their way through gaps that used to be sealed tight.

Call (213) 782-8141

We’re an independent contractor, not a Demilec affiliate. But we’ve worked with Demilec’s open-cell and closed-cell foam systems for over a decade, and we know exactly how their air seal components behave in Southern California attics.

Which Demilec Models This Applies To

Demilec’s attic air sealing systems fall into two main families: the open-cell Sealection 500 and Agribalance lines, and the closed-cell Heatlok HFO and Heatlok Soya lines. The air seal itself isn’t a single “part” you order from a catalog. It’s the installed foam interface where the attic floor meets top plates, penetrations, can lights, and duct chases. That said, the accessory components carry Demilec part numbers: can light covers sized for Demilec foam kits, Demilec’s single-component foam cans for touch-up sealing around plumbing stacks, and the Demilec-branded spray tips and gun assemblies used on their two-part kits.

To identify what you have, check the foam itself. Sealection 500 is a low-density open-cell that compresses under finger pressure and stays slightly soft. Heatlok HFO cures into a rigid, high-density foam with a closed surface you can’t dent easily. If your original installer left a warranty card or invoice, the product name is usually printed there. When we arrive, we match the existing foam type rather than layering a different chemistry on top. Mixing open-cell and closed-cell in the same seal joint can create a condensation point, and that’s a moisture problem waiting to happen. For aftermarket equivalents, we stock Touch ‘n Seal and Great Stuff Pro for small jobs, but for the main seal we always recommend matching Demilec chemistry. The cost difference is small, and the adhesion and expansion rates are engineered for their system. We also stock Reflectix radiant barrier for adjacent attic work.

Signs Your Demilec Attic Air Sealing Is Failing

• Room temperatures swing wildly between day and night. If the attic air seal has cracked or pulled away from framing, conditioned air leaks out and outside air leaks in. You feel it most in rooms directly under the attic, and the HVAC runs longer than it should.
• Your energy bill climbs even though your habits haven’t changed. A degraded Demilec seal increases the air exchange rate in the attic. That forces your AC to work harder all summer. We’ve seen bills rise 15 to 25 percent before a homeowner notices a pattern.
• You smell insulation or dust in the living space below. A split in the air seal lets attic dust, fiberglass particles, or pest droppings drift down through ceiling penetrations. The sneeze-you-can’t-explain is often an air seal problem.
• You see discolored or sagging foam around ceiling penetrations. Heat and time cause open-cell Demilec to shrink slightly, especially in Los Angeles attics that regularly hit 140 degrees in summer. If the foam has pulled back from the framing, air is moving through that gap.
• Pest activity in the attic suddenly increases. Rodents and insects squeeze through gaps the size of a quarter. If the Demilec seal around a plumbing stack or electrical conduit has deteriorated, it’s an open invitation. We handle attic rodent proofing as part of the repair when we find entry points.

Replacement Cost & What’s Included

For a Los Angeles attic, Demilec attic air sealing repair or full replacement typically lands between $950 and $3,400 installed. Here’s how that breaks down:

• Spot repair of 1-3 failed seal areas: $250 to $600. We use Demilec-compatible single-component foam and re-flash the affected penetrations. Most of these qualify for our $50 off any repair over $250 pricing.
• Full air seal reinforcement around all penetrations and top plates: $950 to $1,800 for a standard 1,200-1,800 sq ft single-story home. This covers labor, foam, and cleanup.
• Complete Demilec re-seal plus targeted foam touch-up of the attic floor: $1,800 to $3,400, depending on attic height, access difficulty, and whether we need to remove old degraded material first.

Every job includes our written upfront pricing before work begins. No surprises, no change-order games. And the work is covered by our 90-Day Done Right Promise: if it’s not sealed right, we come back and make it right. We also offer a permanent 5% discount for seniors and veterans, and an $89 seasonal tune-up if you want us to inspect and top off your attic air sealing before each summer.

DIY or Call Us?

You can safely inspect the visual condition of your Demilec seal from the attic access point. Look for foam that’s cracked, pulled away from framing, or missing entirely around can lights and plumbing stacks. That’s diagnostic, not dangerous. But actually repairing the seal is where we tell Los Angeles homeowners to stop. Attics in summer can hit 140 degrees. Working overhead with expanding foam in tight joist bays while balancing on trusses is a fall risk, and misapplied foam can off-gas or expand into places you don’t want it. If the area is small and the attic is a walkable, ventilated space, a homeowner with a Demilec-compatible single-component foam can handle a quarter-sized gap. But for anything larger, or anything involving closed-cell Heatlok, that’s trained technician work. We handle it in one visit, and a live person answers when you call (213) 782-8141.

FAQs