Demilec Attic Insulation Nationwide

Demilec Attic Insulation: The San Antonio Owner’s Guide

If you have Demilec spray foam in your attic and it’s not performing the way it should, we can help. Laurel Attic Insulation San Antonio stocks Demilec-compatible insulation materials and installs them regularly across San Antonio, with most Demilec attic insulation replacements running $1,800 – $4,600 depending on square footage, existing foam condition, and the R-value your attic needs. We carry Demilec materials on our trucks and can typically be on-site the same day you call.

Call (254) 279-0971

Most San Antonio homeowners find out their Demilec insulation has failed in one of two ways: either the upstairs rooms suddenly feel like the attic is leaking heat into them, or the energy bill jumps in July and never quite comes back down. Sometimes it’s visible, like foam that has pulled away from the roof deck in sheets. Other times it’s a slow, invisible decline: the foam is still there, but it’s no longer doing its job because moisture got into it or the original install missed spots that are now showing up as hot ceilings and sweating supply ducts.

Whatever the symptom, the fix usually comes down to the same thing: find where the Demilec foam has failed, remove what needs removing, and re-insulate properly. That’s the work we do here in San Antonio every week.

Which Demilec Models This Applies To

Demilec makes spray foam insulation under two main product families: open-cell (Heatlok HFO and Sealection series) and closed-cell (Heatlok HFO Pro and older Heatlok Soy lines). Open-cell foam is soft and spongy, roughly like a dense foam pillow. Closed-cell is rigid, dense, and hard to the touch. Both are used in San Antonio attics, though open-cell is far more common on the roofline because it allows the roof deck to breathe while still sealing the attic.

Here’s the compatibility gotcha that matters: Demilec open-cell and closed-cell foam are not interchangeable in terms of how they’re installed or what they’re meant to do. Open-cell at 3.5 inches gives you about R-13. Closed-cell at 1 inch gives you about R-7, but it also acts as a vapor barrier, which open-cell does not. If your original installer used open-cell at the roofline and you want to upgrade to closed-cell, you can’t just spray over the top in most cases. The existing foam has to be evaluated for moisture retention first, because closed-cell will trap moisture that open-cell would have let pass through. In San Antonio’s humid climate, that’s a serious consideration.

If you’re not sure what you have, check the foam itself: if you can press your thumb into it and leave a dent, it’s open-cell. If it feels like a hard plastic shell, it’s closed-cell. The original installer may have also left a Demilec label on the foam or on paperwork from the original build. We can identify it on-site in about five minutes.

One more thing worth knowing: Laurel Attic Insulation San Antonio is an independent insulation contractor. We are not affiliated with Demilec, which means we’re free to tell you honestly whether your existing Demilec foam can be saved or whether it makes more sense to replace it, without any pressure to sell a specific brand. If Demilec is the right material for your job, we install it. If another material would serve your attic better, we’ll tell you that too and give you the reason. We also stock Reflectix products for radiant barrier applications where they make sense.

Signs Your Demilec Attic Insulation Is Failing

Here are the five failure patterns we see most often in San Antonio attics with Demilec foam. None of them should be ignored for long, because every one of them gets more expensive the longer it waits.

• Hot ceilings in upstairs rooms during the day. This usually means the foam has pulled away from the roof deck or has gaps in coverage. The attic heats up to 130°F+ in a San Antonio summer, and that heat transfers straight through any bare spot. You feel it first on the ceiling directly under the roof.
• Energy bills creeping up year over year. Demilec foam doesn’t degrade quickly on its own, but install errors, pest damage, or roof leaks that went unnoticed can compromise it. A 20 – 30% jump in cooling costs with no other explanation is often an insulation problem hiding in plain sight.
• Foam that has shrunk, cracked, or pulled away from the framing. This is most common with open-cell foam that was sprayed too thin or applied when the roof deck was too cold. The foam contracts as it cures and leaves gaps at the edges. Once you see daylight or feel a draft through a gap, the seal is broken.
• A musty or chemical smell in the attic, especially after rain. Open-cell Demilec foam can absorb moisture if a roof leak saturates it, and once it does, that moisture rarely dries out in San Antonio’s humidity. The smell is the first clue. Left alone, you get mold growth in the foam and rot on the roof deck behind it.
• Visible rodent tunnels or nesting material in the foam. Rats and squirrels love burrowing through open-cell spray foam. They’ll tunnel through inches of it, destroying the air seal and leaving a mess. If you see tunnels with smooth, rounded edges, you have an active pest problem and your Demilec foam needs replacement in those areas.

Replacement Cost & What’s Included

In San Antonio, Demilec attic insulation replacement typically runs $1,800 – $4,600 for an average single-family home attic between 800 and 2,000 square feet. Smaller jobs, like re-spraying a single section of roofline where foam failed, can run $600 – $1,200. Larger attics or full removal-and-replace jobs (where old foam has to be scraped out before new material goes in) can push past $5,000.

Here’s what drives the price:

• Square footage of the attic floor or roofline being insulated, not the home’s living area
• Foam type: closed-cell costs more per board foot than open-cell, but you need less of it to hit the same R-value
• Whether old foam must be removed first: moisture-damaged or pest-damaged Demilec foam has to come out before new material goes in, and removal adds labor hours
• Access: attics with low clearance, tight rooflines, or difficult entry points take longer

Every Laurel Attic Insulation San Antonio job includes a written price before any work starts. No door-step surprises, no “while we’re here” add-ons. Your written quote covers the materials, labor, cleanup, and a written workmanship guarantee that lasts 365 days. If the repair fails within that year, we come back and make it right at no charge. That’s our 365-Day Done Right Promise, and it’s in writing on every single Demilec insulation job we do in San Antonio.

DIY or Call Us?

Let’s be straight about this: spray foam insulation is not a DIY product. Demilec foam requires professional equipment, precise temperature and humidity conditions, and proper respirator protection during application. Two-part spray foam that’s mixed incorrectly creates poor adhesion, off-gassing problems, and foam that never fully cures. We don’t recommend attempting a self-install, period.

That said, there are things you can do safely before calling us. You can inspect the foam visually from the attic access point with a good flashlight. Look for gaps, cracking, discoloration, or signs of pests. You can check your ceilings for hot spots on a sunny afternoon. You can look at your energy usage history for unexplained spikes. These are all safe, useful checks that help us diagnose faster when we arrive.

What you shouldn’t do is poke at the foam, try to scrape it, or apply any kind of spray coating over it. Damaging the foam’s surface or trapping moisture behind a coating makes the eventual repair bigger and more expensive. If your Demilec foam is failing, call us at (254) 279-0971. We’ll tell you what’s actually wrong, what it takes to fix it, and what it costs. No pressure, no upsell.

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