Demilec Attic Insulation Nationwide | Walt’s Insulation

Demilec Attic Insulation: The Fullerton Owner’s Guide

If you have Demilec spray foam insulation in your Fullerton attic and it’s failing, delaminating, or never performed right from the start, we stock Demilec-compatible materials and can usually be in your attic within 24 to 48 hours. Installed replacement for Demilec attic insulation in Fullerton typically runs $2.50 to $6.50 per square foot depending on whether we’re doing open-cell or closed-cell foam, with most attics landing between $3,800 and $9,500 total. Most owners discover the problem the hard way: a hot upstairs bedroom, a spike in the electric bill, or a musty smell from the attic that won’t go away.

Call (657) 216-9948

We’re an independent insulation contractor, not a Demilec corporate affiliate, and we’ve been installing and replacing their products in Fullerton homes long enough to know exactly what fails and why. Walt Brenner started this company in 2000, and we’ve worked everywhere from the ranch-style streets near the Fullerton Arboretum to the newer developments on the north side of town. If your Demilec foam is letting you down, here’s what you need to know before you spend a dime.

Which Demilec Models This Applies To

Demilec makes two main lines that end up in Fullerton attics: the Heatlok series (closed-cell) and the Sealection series (open-cell). Heatlok HFO and Heatlok Soya are the most common closed-cell products we see in existing homes, while Sealection 500 and Sealection Agribalance show up in open-cell applications. The compatibility gotcha most homeowners don’t know: Heatlok and Sealection are not interchangeable in a repair scenario. You can’t patch an open-cell failure with a closed-cell product and expect it to perform, because closed-cell foam acts as a vapor barrier and open-cell doesn’t. Mixing them can trap moisture against your roof deck.

If you’re not sure which product is in your attic, look for the manufacturer label on the foam itself or check any paperwork from the original install. No label? The foam’s texture gives it away: closed-cell feels dense and rigid, almost like a hard sponge, while open-cell is softer and you can dent it with a finger. When we do a Demilec repair in Fullerton, we match the existing product line before we spray anything new. We also keep Reflectix radiant barrier on the truck for hybrid retrofit jobs where adding a barrier makes more sense than pulling out old foam.

On the OEM vs. aftermarket question: we use genuine Demilec product when the job calls for it, because their foam chemistry has specific expansion rates and R-values per inch that affect the final install. There are aftermarket equivalents out there, but for a true Demilec repair we don’t gamble on substitutes. R-6.5 to R-7 per inch for Heatlok and roughly R-3.8 to R-4.2 per inch for Sealection are the numbers we expect, and those specs matter for Fullerton’s climate where attic temperatures regularly hit 140 degrees in August.

Signs Your Demilec Attic Insulation Is Failing

• Upstairs rooms won’t hold temperature. Closed-cell Demilec should keep attic heat out. If your upstairs is 10 degrees warmer than downstairs in July, the foam may have pulled away from the roof deck. We see this most often in older Fullerton homes where the original installer sprayed foam too cold and it never fully adhered.
• Visible cracks or gaps in the foam. Demilec foam shrinks slightly as it cures. Normal shrinkage is minimal, but poor installation or chemical mix errors can cause it to pull back from rafters by a half-inch or more. Any gap is a thermal leak that compounds over time.
• A chemical or fishy smell that won’t dissipate. This is the bad one. In a small number of Demilec installs, improper chemical ratios or insufficient curing time produce persistent off-gassing. If you’re smelling something odd months after install, that’s a real problem that needs to be assessed and often removed entirely.
• Damp spots or water staining on the roof deck. Open-cell Sealection is vapor-permeable, which is fine when installed correctly. But if attic ventilation is poor, trapped humidity can condense on the foam and rot the wood behind it. Fullerton’s marine-layer mornings make this more common than you’d think.
• Rodents or termites working through it. Spray foam isn’t food, but rats will tunnel through open-cell foam, and termites can bore through closed-cell. We’ve pulled foam out of attics near the Fullerton train station side of town that looked like Swiss cheese.

Replacement Cost & What’s Included

Here’s what you can expect to pay in Fullerton, current market rates:

• Removal of failed Demilec foam: $1.25 to $2.50 per square foot, depending on adhesion and access. Open-cell comes out faster than closed-cell, which often has to be scraped and ground off.
• Open-cell replacement (Sealection or equivalent): $2.50 to $4.00 per square foot installed. Lower cost, good thermal performance, but lower R-value per inch.
• Closed-cell replacement (Heatlok or equivalent): $4.00 to $6.50 per square foot installed. Higher R-value, acts as a moisture and air barrier, but costs more and requires more prep.
• Attic air sealing before re-foaming: $400 to $900 for a typical Fullerton attic. You skip this and you’re throwing money away, because sealing gaps is what makes foam perform.

Every quote we write in Fullerton includes labor, materials, disposal of the old foam, and cleanup. The Done Right Promise covers our workmanship for life, so if the new foam ever fails because of how we installed it, we fix it at no charge. We don’t hide line items in the fine print, and we’ll give you a written price before any work starts. We also offer a free second opinion on any written estimate you’ve gotten from another contractor, and there’s no trip charge anywhere in our service county.

DIY or Call Us?

Two-part answer. You can absolutely check the visible condition of your Demilec foam from the attic access: look for gaps along rafters, press your hand into the foam to check adhesion, and note any unusual smell. If the attic access is a scuttle in a hallway ceiling, fine, take a look. But actual spray foam repair is not a weekend project. Demilec foam is applied with high-pressure equipment, and the two chemical components have to mix at the right ratio under the right temperature conditions. Get the chemistry wrong and you’ll have uncured foam off-gassing in your attic while the surface looks fine. That’s how homes end up with chemical smells that never go away. If the foam has failed, the responsible move is to call someone who does this every week. We answer the phone live, 24/7, at (657) 216-9948, and we’ll tell you honestly whether you need a full removal or just a targeted repair.

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