Demilec Attic Air Sealing Nationwide | Walt’s Insulation

Demilec Attic Air Sealing: The West Hollywood Owner’s Guide

If your Demilec spray foam attic air sealing has failed or degraded, we stock Demilec-compatible air sealing materials on our trucks and can usually complete the repair or reapplication the same day in West Hollywood. Installed pricing for Demilec attic air sealing correction in this area typically runs $1,400 to $3,800 depending on attic size, access, and how much of the existing seal needs to be removed and redone. Most West Hollywood homeowners discover the problem the same way: a sudden spike in their July and August cooling bills, a whiff of attic dust in the hallway, or a pest control tech pointing out gaps around plumbing penetrations during a routine inspection.

Call (213) 527-4062

Here’s the thing about spray foam air sealing: it fails quietly. You don’t get a warning light. You get a room that won’t hold temperature, a second-floor bedroom that’s always five degrees warmer than the rest of the house, or ants showing up around a can light. We’ve been fixing Demilec applications in West Hollywood since 2000, and we can tell you exactly what you’re dealing with and what it’ll take to fix it, usually without a second trip.

Which Demilec Models This Applies To

Demilec produces two primary spray foam lines used in attic air sealing: open-cell products like Sealection 500 and closed-cell products like Heatlok HFO Pro. The open-cell foam is softer, breathable, and typically applied at depths of 5 to 10 inches. The closed-cell foam is rigid, acts as its own vapor barrier, and is applied in thinner lifts. Both fail differently, and knowing which one is in your attic changes the repair approach. If you have the original invoice or permit paperwork, look for the product name on the spec sheet. No paperwork? We can identify it in about three minutes on site.

The compatibility gotcha with Demilec that most people don’t know: you can’t just spray a different manufacturer’s foam over uncured or improperly adhered Demilec and expect it to bond. Open-cell and closed-cell chemistries don’t always play well together, and some aftermarket sealants will separate from old Demilec within a season. We use Demilec-compatible materials for repairs because in our experience, mixing brands on a repair is how you end up back in the same attic in eighteen months. Walt’s Insulation is an independent service provider, not affiliated with Demilec, which means we recommend what actually works for your specific failure, not what a manufacturer rep wants us to push.

Signs Your Demilec Attic Air Sealing Is Failing

• Room temperature swings between floors. When Demilec air sealing cracks or pulls away from framing around top plates and penetrations, conditioned air escapes into the attic. The upstairs rooms suffer first because heat rises straight through those gaps.
• Dust coming from recessed lights or ceiling fans. Air sealing around electrical boxes and fan housings is supposed to stop attic air from pulling into the living space. If you see dust streaks or feel a draft at the ceiling, the seal has broken down.
• A cooling bill that climbed 20 to 30 percent without a rate change. West Hollywood summers are hot, and a failed air seal means your AC is conditioning attic air. When we test homes on the west side of town, the ones with failed seals are running their systems noticeably harder.
• Pest activity in the attic. Rodents and insects find gaps. Demilec foam that has shrunk or separated from wood framing leaves openings along the sill plate and roof junctions that pests exploit. If you’re hearing scratching, check the perimeter seals before calling pest control.
• Visible shrinkage or cracking at the roofline. Over time, especially in attics that hit 130 degrees or more in summer like most West Hollywood attics, closed-cell foam can shrink slightly and pull away from rafters. That hairline crack is a leak path for air and moisture.

Replacement Cost & What’s Included

For a typical West Hollywood home, correcting failed Demilec attic air sealing runs $1,400 to $3,800 installed. Smaller attic spaces around 1,000 square feet with straightforward access land at the lower end. Larger attics, low-slope roofs, or situations where we need to remove failed foam before reapplying push toward the higher end.

What’s included: a full attic inspection to map every failure point, removal of delaminated or shrunken Demilec material where necessary, reapplication of Demilec-compatible air sealing at all penetrations, top plates, can light housings, and junctions, and a post-job thermal verification pass. Every repair over $200 carries $40 off, and we offer a free second opinion on any written estimate. And yes, the work is covered by our Done Right Promise: if it’s not done right, we make it right. That’s not a limited-time warranty. That’s for as long as you own the house.

DIY or Call Us?

What you can safely do: inspect your attic in daylight, look for visible cracks, gaps, or shrunken foam around roof penetrations, and check for daylight coming through around plumbing vents and electrical boxes. That’s diagnostic work, not repair work, and it gives us useful information before we arrive.

What you should not do: attempt to remove or reapply spray foam yourself. Demilec products, like all two-part spray foam systems, involve isocyanates during application. The chemistry requires proper respiratory protection, ventilation, and temperature control. Improper application can off-gas into your living space for weeks. The foam also bonds almost instantly to skin and clothing. This is one of those jobs where the savings from DIY evaporate the moment something goes wrong, and they go wrong often. Call us at (213) 527-4062. Walt Brenner has seen enough DIY spray foam attempts to tell you it’s cheaper to get us in before the cleanup becomes its own job.

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