Demilec Attic Insulation Nationwide

Demilec Attic Insulation: The Los Angeles Owner’s Guide

Demilec attic insulation replacement in Los Angeles typically runs $2,800-$5,400 for a complete removal and reinstall in a 1,200-2,000 square foot home, and we stock Demilec-compatible open-cell and closed-cell foam systems for same-day starts on most jobs. Most homeowners notice the problem first as a spike in their LADWP bill during a heat wave, or they feel a hot spot in a ceiling that used to stay cool. The foam has pulled away from the roof deck, cracked at the joist line, or settled below the labeled thickness - and now conditioned air is bleeding straight into the attic.

Call (628) 226-1097

Which Demilec Models This Applies To

Demilec’s two primary product lines in Los Angeles attics are Heatlok HFO High Lift (closed-cell, 2.0 lb density, used in rafter cavities for unvented conditioned attics) and Sealection 500 (open-cell, 0.5 lb density, common in vented attic floor applications). The spec label matters: Heatlok HFO is sprayed to 5.5 inches for R-38 in a single pass, while Sealection 500 needs 10 inches to hit the same R-value. We’ve found mismatched installs in Mid-City and Koreatown where a previous contractor spec’d open-cell at rafter depth and the homeowner ended up with R-19 where the Title 24 code table called for R-38.

To identify what you have, check the ICC-ES evaluation report number stamped on the sill plate or noted in your original permit paperwork - ESR-1233 for Sealection 500, ESR-2077 for Heatlok HFO. If the foam is yellow-tinted and rigid enough to walk on, it’s closed-cell. If it’s soft, white, and you can press a thumb into it, it’s open-cell. We carry both formulations on our rig, plus Demilec’s APX hybrid system for difficult-access cathedral ceilings in older Los Angeles hillside homes where standard lift hoses won’t reach.

OEM Demilec foam is what we default to for warranty continuity, though we also source equivalent-density foam from Icynene and Johns Manville when the original product has been discontinued or when a homeowner wants to compare spec sheets side by side. We do not push proprietary lock-in - our material list includes Owens Corning, Johns Manville, Knauf, Rockwool, CertainTeed, Icynene, Demilec, and GreenFiber.

Signs Your Demilec Attic Insulation Is Failing

• Hot ceiling patches in summer. The foam has delaminated from the roof deck, creating an air gap that lets roof heat radiate through. In Los Angeles, this shows up first on south-facing slopes after about 8-10 years of thermal cycling.
• Musty attic smell entering living space. Open-cell Demilec can act as a moisture reservoir if the attic wasn’t properly vented; when relative humidity spikes during Santa Ana wind events, the foam holds water against the drywall.
• Visible cracking or shrinkage at joist edges. Closed-cell Heatlok can pull away from framing members if the substrate wasn’t primed or if temperature at application was below 60°F - a common shortcut during rushed winter installs in Los Angeles.
• Energy bill jumps 20% or more year-over-year. The insulation hasn’t disappeared; it’s just no longer continuous. Blower-door testing - a pressurization reading that shows, in one number, how much air your building envelope is losing - will typically reveal the attic as the dominant leakage path.
• Pest intrusion at foam edges. Rodents exploit gaps where foam meets top plates or chimney chases. We’ve found this repeatedly in 1940s-1960s ranch homes in the Leimert Park corridor where unvented knee walls and bypassed soffit chases are still the norm rather than the exception.

Before

After

Replacement Cost & What’s Included

What drives the range: attic square footage, existing foam thickness that must be removed (closed-cell is labor-intensive to scrape), accessibility (hatch size, roof pitch), and whether the original install included proper air sealing or we’re doing that from scratch. Every quote is a flat price with a written scope and written warranty before anyone lifts a tool - Haven Standard Clause 1. We also publish before-and-after blower-door numbers on every applicable job so you can verify the air-sealing result in CFM50, not promises.

Topside Attic Insulation Los Angeles is an independent service provider, not affiliated with Demilec.

DIY or Call Us?

There’s a safe middle ground and a hard stop. Homeowners can inspect the attic hatch with a flashlight for visible gaps, measure existing foam thickness with a ruler against the labeled R-value on the rafter tag, and photograph any cracks for documentation. What you should not do: attempt to remove or apply spray foam yourself. Closed-cell Demilec requires full-face respirators with organic vapor cartridges, forced ventilation, and substrate temperatures between 60-90°F for proper adhesion - off-ratio foam cures brittle and delaminates within two seasons. We’ve been called to fix DIY spray foam in Eagle Rock and Silver Lake where the homeowner saved $1,200 upfront and spent $4,600 correcting the removal and reapplication.

Seal the holes first. Then measure the R-value. In that order.

Call (628) 226-1097 for a free estimate. We answer live, 24/7.

FAQs