Demilec Attic Insulation Nationwide

Demilec Attic Insulation: The Houston Owner’s Guide

If you have Demilec spray foam or blown-in attic insulation that’s underperforming, we stock and install Demilec-compatible attic insulation across Houston, with most jobs running between $1,800 and $4,600 depending on attic square footage and the product line your home needs. We keep Demilec open-cell and closed-cell foam, plus Sealection 500 and Agribalance, available for same-week scheduling, and we’ll give you a written price before any work starts. Most Houston homeowners don’t discover a Demilec issue until they walk upstairs in July and realize the second floor never quite cools, or they spot a utility bill that jumped 30 percent year over year without an obvious reason.

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The reality with Demilec products is that they’re genuinely good insulation. But no product survives every attic forever. Houston’s heat and humidity combination, with attic temperatures routinely hitting 140 degrees in August, puts stress on spray foam that a house in Ohio never sees. When it fails, it rarely fails all at once. It starts as a small separation at the roofline, a gap where the foam pulled slightly off the sheathing, and from there the performance declines a little more each summer.

We’re an independent Houston insulation contractor, not affiliated with Demilec, and we’ve been installing their products long enough to know exactly what holds up in this climate and what needs a second look.

Which Demilec Models This Applies To

Demilec sells several product lines, and the compatibility question matters more than most homeowners expect. The big ones we see in Houston homes are Sealection 500 (open-cell, half-pound foam), Heatlok HFO (closed-cell), and Agribalance (also open-cell, with a higher soy content). Each one has a different expansion rate, a different R-value per inch, and a different failure pattern.

Sealection 500 is the most common Demilec product in Houston attics. It’s open-cell, which means air can move through it slowly, and it does most of its work by sealing air leaks rather than trapping heat. The gotcha: open-cell foam won’t perform in a Houston attic if it was installed at less than 4 inches thick. The R-value drops off a cliff below that. We’ve measured attics in Meyerland that were sprayed at 3 inches to save money and the homeowners never knew until they called us for a second opinion.

Heatlok HFO is closed-cell and more expensive, but it’s what we recommend for Houston attics where the roofline is sprayed and the space underneath is part of the conditioned envelope. It’s denser, handles humidity better, and holds its R-value longer. If you’re deciding between OEM Demilec replacement foam and a quality equivalent, here’s the honest answer: the foam itself is manufactured to a spec, and the right competing product, installed properly, will perform nearly identically. What matters more in this climate is the installer’s understanding of Houston’s dew point and humidity cycles, which is where most jobs go sideways. And by installing the licensed material and documenting what went in, you also avoid warranty issues and building-code questions if you ever sell the house.

If you don’t know which Demilec product is in your attic, look for a label near the attic hatch or on the roof deck where the original crew applied it. No label? We can identify it by feel and density during a free attic inspection.

Signs Your Demilec Attic Insulation Is Failing

Here’s what we hear from Houston homeowners before we climb into their attics, and what each symptom usually points to:

• Second floor runs 8 to 12 degrees warmer than the first floor in summer. This usually means the foam pulled back from the roof deck and created an air gap. Hot attic air gets pulled into that gap, and the foam’s ability to slow heat transfer drops sharply.
• Utility bills spike in July and August while the thermostat setting never changed. Open-cell foam that has absorbed Houston humidity over multiple years starts losing R-value. If the foam feels like a damp sponge, it’s done. That moisture is also the start of a mold and sheathing problem.
• You can smell the attic from inside the house. Foam that has separated from the roof deck lets attic air, dust, and whatever else is up there, including the occasional Texas rat, move into the living space. That’s a seal failure, not just an odor issue.
• Visible shrinkage or cracks in the foam around the roofline or around plumbing penetrations. Demilec open-cell foam shrinks slightly as it cures, but big gaps, anything you can slide a pencil into, are a sign the installer mixed the two-part foam incorrectly or sprayed too thick in one pass. The foam will never fix itself.
• Insulation depth near the eaves is thinner than it is toward the ridge. Spray foam that wasn’t applied to spec in the first place. In Houston’s slope-and-soffit attic geometry, this is common, especially in 1970s ranch houses where the roof pitch is shallow. The fix usually involves respraying the affected sections and adding a thermal barrier where one was skipped.

Replacement Cost & What’s Included

For a typical 1,800 to 2,400 square foot Houston home, full Demilec attic insulation replacement runs between $2,800 and $4,600 for open-cell Sealection 500, and $4,000 to $6,800 for Heatlok HFO closed-cell. Partial repairs, where we cut out failed sections and respray those areas, run between $900 and $2,200 depending on how much foam has separated from the deck.

Every price we quote includes the material, the labor, the prep work to protect your ceiling and ductwork, and a written guarantee on the installation. That’s part of what we call The Kingswell Way: you get a written price before any work starts, a committed arrival window, a clean job site when we leave, and a written guarantee that covers the work for 365 days. Glenn Hartley, who runs our Houston operation, was trained in building science at Los Angeles Trade-Technical College, and he’s spent over two decades in the trade. His rule, and ours: if we wouldn’t put it in our own attic, we’re not putting it in yours.

One thing to know about Demilec pricing in Houston specifically: don’t let a contractor quote you a “per square foot” number and then add a separate line for prep, disposal, or “difficult access” once they see your attic. A real written quote accounts for all of that upfront. Ours always does.

DIY or Call Us?

Here’s where we’ll be straight with you. Working with spray foam is not a DIY job, and it’s not something we’d tell a homeowner to attempt even if they’re handy. The two-part mixture cures quickly, gives off fumes during application that require ventilation and respirator protection, and if you mix it wrong, you get a sticky mess that has to be mechanically scraped off the roof deck. That’s an expensive mistake.

What you can safely do is assess the scope. Get up into your attic on a cool morning, before 8 a.m. in a Houston summer, and look for gaps, damp-looking foam, or places where the foam pulled away from the wood. Take photos. That tells you whether you had a full failure or a partial one. But once you’ve determined the insulation isn’t doing its job, the repair belongs in the hands of someone who does it every day. We carry Demilec product on our trucks for the most common repair scenarios, which means an inspection and a fix often happen in a single trip. Call us at (903) 447-8369 and we’ll get you scheduled.

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