Demilec Attic Air Sealing: The Long Beach Owner’s Guide
Demilec attic air sealing in Long Beach typically runs $1,450 to $3,200 for a full attic treatment using Heatlok HFO or Sealection 500, and our trucks carry Demilec-compatible sealant kits daily, so we can usually start within 48 hours of your call. Most Long Beach homeowners discover an air sealing failure the same way: a bedroom that stays five degrees warmer than the hallway, a utility bill that crept up $40 a month without explanation, or dust settling on boxes in the attic within weeks of cleaning. If you have a Demilec spray foam system that was installed years ago and you’re now feeling drafts at ceiling fixtures or smelling attic heat in the upstairs hallway, the air seal has likely developed gaps around penetrations, or the original installer missed the gaps entirely. We diagnose exactly where the seal failed and re-treat only what needs it. You’ll know the written price before anyone opens the attic hatch.
Which Demilec Models This Applies To
This page covers air sealing for the two Demilec spray foam systems most common in Long Beach attics: Heatlok HFO and Sealection 500. Heatlok HFO is the closed-cell, two-part kit we see most often in retrofit attics near Belmont Shore and Naples, where roof decks are tight and moisture control matters. Sealection 500 is open-cell, which some Long Beach homes have on the attic floor rather than the roofline. The compatibility gotcha owners hit is this: if your attic has existing open-cell foam, you cannot simply patch it with a closed-cell kit and expect a proper seal. The two cure differently, and the seam between them will eventually pull apart. The safe fix is to match product to product, or to remove the failed section and start fresh. A Demilec label is usually visible on a rafter or rim joist near the attic hatch with the product name and batch number, but if the label has faded or been painted over, we identify the type by density and cell structure in under ten minutes with a ladder and a flashlight.
On the OEM versus aftermarket question: Demilec’s own HFO blowing-agent reformulation from several years back means that some older Heatlok kits and newer cartridges don’t bond reliably at the seam. We stock current-generation Demilec kits for exact matches, plus proven compatible alternatives from a short list we trust for edge cases like pet-safe re-coats where an owner wants low-VOC options. You’ll never get mystery-brand foam from us just because it was on sale at a supply yard.
We’re an independent insulation installer in Long Beach. Thistledown Insulation Long Beach is not affiliated with Demilec, but we install and service their products regularly, along with seven other brand lines including Reflectix for radiant barrier work.
Signs Your Demilec Attic Air Sealing Is Failing
- Upstairs rooms won’t hold temperature. When the air seal around attic penetrations fails, conditioned air escapes into the attic and hot or cold attic air drops into the living space. Rooms directly under the attic hatch or near recessed lights feel it first.
- You can feel air moving around ceiling light fixtures or bath fans. Hold a damp hand near a ceiling penetration on a windy day. If you feel a draft, the seal around that fixture has opened, or was never sealed at all.
- Dust accumulates in the attic and the rooms below it. Attic air carries fine dust through unsealed gaps. If you’ve dusted the hallway twice this month and it’s still gritty, the attic is leaking into the house.
- Utility bills climb without a change in usage. A compromised attic air seal can add $35 to $60 a month to a Long Beach cooling bill from May through October, when attic temperatures routinely reach 140 degrees. The leak is small; the compounding waste is not.
- You smell heat or see shimmer at the attic hatch seam. Heat from the attic finds its way through any gap. A warm hatch, a visible gap around the trim, or a dusty outline where the hatch seats are all signs the perimeter seal is gone.
Replacement Cost & What’s Included
For a full Demilec attic air sealing job in Long Beach, expect between $1,450 and $3,200 depending on attic square footage, ceiling fixture count, and whether the existing foam is Heatlok HFO or Sealection 500. Smaller single-story attics under 1,000 square feet usually land in the $1,450 to $1,900 range. Two-story homes with multiple bath fans, recessed lights, and a drop-down attic ladder go higher because there are simply more penetrations to air seal.
Every quote includes the sealant product, prep and cleanup, waste removal, and verification before we leave. You’ll see the line items, not just a lump sum. Demilec-compatible foam kits run $320 to $520 per kit at Long Beach supply houses, and a typical attic uses two to four kits. As of this writing, our installed pricing reflects those supply costs plus labor and warranty coverage.
Our work carries the 365-Day Done Right Promise: if the air seal doesn’t hold or we miss a penetration and you discover it within a year, we come back and re-seal it. No debate, no charge.
| Scope | Typical Range | What It Includes |
|---|---|---|
| Single room or hatch perimeter seal | $175 – $450 | Seal kit, labor, cleanup, verification |
| Standard single-story attic | $1,450 – $1,900 | Full penetration sealing, one-day job |
| Larger or two-story home | $2,100 – $3,200 | Full sealing, multiple fixtures, possible two-day job |
DIY or Call Us?
You can safely inspect your attic for obvious gaps around recessed lights, bath fan housings, and the attic hatch from the floor below with a flashlight. What you should not do is attempt to remove or re-spray Demilec foam yourself. Closed-cell spray foam cures through an exothermic reaction. Applied incorrectly, it can smolder, off-gas, or bond in a way that has to be chiseled out later. If you already own a Demilec kit and want us to apply it, we will, but most Long Beach homeowners find it cheaper and safer to let us supply and install matched product. Our techs are trained on Demilec application and carry fresh kits on the truck. Call (562) 471-3972 and ask Neil or a crew lead what the fixed price would be for your attic.
FAQs
Properly applied Demilec Heatlok HFO or Sealection 500 air sealing lasts the life of the attic in most Long Beach homes, typically 20 to 30 years before any meaningful degradation. The failures we see are almost always installation gaps from the original job, not product failure. Call (562) 471-3972 if you want us to inspect yours, and we’ll tell you honestly whether it needs patching or nothing at all.
Yes, and this is what we do in most cases. Isolated gaps around fixtures or the hatch perimeter are point-repairs. A full re-spray is only necessary when the original application was thin, uneven, or the wrong product for the surface. We’ll give you a written price for the repair scope only, never a full job if the full job isn’t needed.
A standard single-story Long Beach attic takes one day, usually four to six hours including setup, sealing, and cleanup. Two-story homes with many ceiling fixtures may run into a second morning. You’ll have an exact arrival window and a written price before the crew shows up.
We stock current-generation Demilec Heatlok HFO and Sealection 500 kits on our Long Beach trucks, plus compatible alternatives for pet-safe recoat work. If you need a specific Demilec product matched to an existing installation, we’ll confirm what’s on board when you call, and if it isn’t, we’ll have it on the truck within one business day.
Call Thistledown Insulation Long Beach
The fastest way to get a Demilec attic air sealing assessment in Long Beach is to call (562) 471-3972. A live person answers, 24/7. We’ll schedule a look at your attic, tell you exactly what’s there now, what failed, and what it costs to fix, all in writing before any work starts. Neil Barron and the crew know these attics, from the bungalows off Fourth Street to newer builds east of the 710. Know what you’re getting before we touch a wall.
Written by Neil Barron, Owner, Thistledown Insulation Long Beach at Thistledown Insulation Long Beach, serving Long Beach and nearby areas.