Demilec Attic Insulation: The Houston Owner’s Guide
We stock and install Demilec spray foam attic insulation across Houston, with most residential jobs running $2,800 to $7,400 depending on square footage, current R-value, and whether you’re adding to existing insulation or starting fresh. Same-week scheduling is standard, and our trucks carry enough material to handle most single-family attics in one visit.
Most Houston homeowners call us when they notice the signs that their Demilec foam isn’t performing: a spike in the July utility bill, uneven room temperatures between the first and second floor, or a musty smell that suggests air is moving through the attic where it shouldn’t. Sometimes it’s simpler than that: they look up, see gaps or shrinkage in the foam, and want to know if it’s a repair or a full replacement. The answer is usually more straightforward than people expect.
Which Demilec Models This Applies To
Demilec makes two broad product lines that dominate the Houston residential market: Heatlok HFO closed-cell foam and Sealection 500 open-cell foam. We work with both, plus the older Heatlok Soy lines still present in homes built from roughly 2010 through 2018. If you don’t know which one is in your attic, the foam’s texture gives it away fast: closed-cell feels rigid and dense, like a firm pool noodle, while open-cell is softer and more sponge-like.
What matters for replacement compatibility is thickness and substrate, not just brand. Demilec foam must be applied at specific depths to hit Houston’s recommended R-values – generally R-38 to R-49 for vented attics, which means 6 to 9 inches of open-cell or 5 to 7 inches of closed-cell. A foam that was sprayed too thin during the original install will underperform no matter how good the material is, and patching thin spots with the wrong density makes it worse. We match the existing foam’s chemistry rather than mixing product lines.
One Houston-specific note: Demilec closed-cell foam acts as its own vapor barrier, which matters in our humidity. If someone patches open-cell into a closed-cell cavity, condensation can collect at the seam and rot the decking behind it. We see this in older Meyerland and Bellaire homes where a previous contractor cut corners. Alden Insulation Houston is an independent service provider, not affiliated with Demilec, but we install their products by the manufacturer’s spec because the physics don’t care about brand loyalty.
Signs Your Demilec Attic Insulation Is Failing
- Utility bills climbing year over year with no change in usage. Foam shrinks as it ages, pulling away from rafters and leaving air channels that let conditioned air escape. In Houston’s summer, a 1/4-inch gap around a rafter bay adds up to real money.
- Upstairs rooms running 5 to 8 degrees warmer than the thermostat setting. This usually means the foam at the roofline has degraded or was never thick enough at the eaves, where most affordable installs get skimpy.
- Pest or rodent activity in the attic. Demilec foam is not pest-proof, and rats chew through open-cell easily. Chewed channels through the foam destroy the air seal and bring droppings into the insulation layer.
- Visible gaps, cracks, or pull-away at the foam-to-wood seams. Foam that separates from the decking leaves a direct thermal bypass. You can see it with a flashlight from the attic access, no specialty equipment needed.
- Musty odor upstairs after rain. If a roof leak sits behind closed-cell foam, the foam traps the moisture against the wood. The smell is your warning that the decking is getting soft and the sealed cavity is hiding the damage.
Replacement Cost & What’s Included
In Houston, full attic foam removal and re-spray with Demilec Heatlok HFO typically runs $4,200 to $7,400 for a 1,500 to 2,500 square foot attic. A targeted repair – removing a failed section, re-spraying the affected bays, and re-establishing the air seal – runs $900 to $2,200 depending on access and how much old foam has to come out first. Blown-in fiberglass over existing foam costs less, but it doesn’t fix a broken air seal; it just hides it.
Every quote we give is written, and it’s the number you pay. The price includes removal of the compromised material, prep, the Demilec product, cleanup, and disposal. It also includes the 365-Day Done Right Promise: if the work fails within a year, we return and make it right at no charge. That’s in writing before a single tool comes off the truck.
A note on timing: Demilec foam needs the attic temperature below 110 degrees to apply properly, which makes Houston attics a problem in August. We schedule early-morning crews in summer months, and sometimes that pushes a job by a day or two. We’d rather tell you that upfront than spray foam that cures wrong.
DIY or Call Us?
What a homeowner can reasonably check: visible gaps in the foam, signs of pest traffic, and whether the upstairs temperatures match the thermostat. A flashlight and a thermometer will answer the question in ten minutes. What’s worth leaving alone: removing failed foam, cutting out sections to inspect the decking, and spraying anything. Foam removal without the right tools tears the wood and turns a repair into a deck replacement. And Demilec’s two-part chemistry requires exact mixing ratios and temperature control; a botched DIY re-spray off-gasses in a way you don’t want inside your house.
Bryce Holloway has been running crews in the Houston area for over a decade, including jobs deep in Meyerland where slab foundations and humid air make a tight thermal envelope non-negotiable. His read on a foam failure is methodical: find the air leak first, then decide what gets removed and what gets re-sprayed. Call (806) 581-1010 and we’ll schedule a look at the attic. The estimate is free, it’s in writing, and the number doesn’t move.
FAQs
Closed-cell Demilec foam installed correctly holds its insulating properties for 20 to 30 years in Texas conditions. Open-cell wears faster under the same heat and humidity, typically 10 to 15 years before performance drops enough to notice on the bill. The foam does not biodegrade, but the air seal it creates degrades when the material shrinks or separates. Houston’s attic temperatures routinely reach 140 degrees in July, which accelerates shrinkage more than any other factor. If your foam is past year 12 and the upstairs feels different, it’s worth an inspection. Call (806) 581-1010 and we’ll tell you honestly whether it needs work.
Yes, in most cases a failed section can be cut out and re-sprayed without replacing the entire attic. The job is viable when the failure is localized: one rafter bay, one corner where rodents chewed through, or one section that pulled away from the decking. Full replacement only makes sense when the original foam was sprayed too thin across the entire attic or water damage has compromised the decking underneath. The right call becomes obvious once the foam comes off and you can see the wood.
Most Demilec repairs run 4 to 6 hours from setup to cleanup, including removal of the failed section, re-spray, and a final air-seal check. A full attic re-spray is typically a one-day job for a two-person crew, though larger or heavily damaged attics can stretch into a second day. We schedule inside a specific window, not a half-day range, and the crew shows up in uniform with the equipment already set up before we start the clock.
We keep Demilec Heatlok HFO and Sealection 500 materials in regular stock, along with the mixing and spray equipment required for both closed-cell and open-cell applications. For non-Demilec needs, we also work with Reflectix radiant barrier and the broader product lineup from Owens Corning, Johns Manville, Knauf, Rockwool, CertainTeed, Icynene, and GreenFiber. Most Houston jobs are ready to schedule within the week. Call (806) 581-1010 for a written estimate and a firm date.
Good insulation doesn’t announce itself – you notice it on your utility bill. When the bill says something’s wrong, we’ll find it, price it, and fix it in writing.
Written by Bryce Holloway, Owner, Alden Insulation Houston at Alden Insulation Houston, serving Houston and nearby areas.