Demilec Attic Air Sealing: The Houston Owner’s Guide
If you’ve got a Demilec spray foam attic that’s starting to let Houston’s heat creep back in, this page is for you. We stock and install Demilec-compatible attic air sealing products at Thistledown Insulation Houston, with most jobs running between $2,100 and $4,800 depending on attic size and what’s failing. You’ll have a written price before we touch anything, and we can usually have a crew at your house within 48 hours.
Most Houston homeowners discover the problem the same way: the upstairs bedroom won’t hold its temperature anymore, the AC runs noticeably longer in July, or they open the attic hatch and feel a wave of hot air that used to stay outside. Sometimes it’s a visible gap where the foam has pulled away from the roof deck. Sometimes it’s a musty smell that suggests air is moving somewhere it shouldn’t be. Either way, small air leaks in a Demilec-sealed attic quietly undo the work the foam was supposed to do.
Quick answer: we match the air sealing product to your existing Demilec foam and the specific gaps in your attic, install it in one visit, and back the work with our 365-Day Done Right Promise. Call (430) 226-1334 and a live person answers, day or night.
Which Demilec Products This Applies To
Most Demilec attic systems in the Houston area fall into two camps: open-cell foam like the Sealection 500 series, or closed-cell foam like Heatlok HFO. Each needs a different air sealing approach, because open-cell breathes and closed-cell doesn’t. Matching the right air sealing material to the right foam matters more than most homeowners realize.
The compatibility gotcha we see all the time: you can’t just grab any caulk or canned foam off a shelf and expect it to bond to cured Demilec foam. We use materials with the right chemical profile to adhere without degrading the existing foam over time. In Houston’s summer, attic surface temperatures routinely hit 140°F or higher, and the wrong sealant will dry, crack, or peel within one season. That means you pay twice, once for the wrong product and once for the right one.
On the OEM versus aftermarket question: Demilec and its parent company Huntsman sell proprietary air sealing accessories, but quality aftermarket equivalents often cost less for the same performance. We’ll quote you either option in writing, explain the difference in plain language, and let you decide. If we can’t verify that an aftermarket product will bond correctly to your specific foam, we won’t offer it. Neil Barron walks every attic twice before quoting, once to see what’s there and once to think through what the family actually needs. Tell me what’s in the room on the other side of that wall, and I’ll tell you exactly what goes between it.
Signs Your Demilec Attic Air Sealing Is Failing
- Upstairs rooms are hard to cool in the afternoon. When air sealing fails, hot attic air pushes into conditioned space and your AC works harder. You’ll notice the upstairs running 4 to 7 degrees warmer than the thermostat says it should be.
- You can feel air moving near ceiling fixtures, recessed lights, or the attic hatch. These are the classic Demilec air sealing failure points. Gaps around penetrations let conditioned air escape into the attic, and you can often feel a faint draft with your hand.
- Dust accumulates faster than it used to. Air leaks pull in attic dust, insulation particles, and whatever else is up there. If you’re dusting the same surfaces every few days, something’s moving air through the ceiling plane.
- Your energy bills rise without a change in behavior. Houston summers are brutal enough without air leaks. A failed air seal can add 10 to 15 percent to your cooling costs without you touching the thermostat.
- You find a gap where the foam meets the roof deck or top plate. Open-cell Demilec foam can shrink slightly in extreme heat cycles. Over several Houston summers, this creates a visible crack at the seam where the foam meets framing. That crack is an air highway.
Replacement Cost & What’s Included
What you’ll pay for Demilec attic air sealing in Houston depends on three things: attic square footage, how many penetrations need sealing, and whether the existing foam needs repair before resealing. Most single-family homes in neighborhoods like the Heights, Katy, Sugar Land, and Spring run between $2,100 and $4,800.
Every job includes a walkthrough, a written price before work starts, and a thorough clean-up afterward. Shoe covers go on at the front door, drop cloths cover the hallway to the attic hatch, and you get a photo of the cleaned area before our van leaves. The labor is done by background-checked, uniformed technicians, and the work is covered by our 365-Day Done Right Promise. If it’s not done right, we make it right, no debate, no fine print.
We’re an independent Houston insulation company, which means we’re not part of Demilec. We stock Demilec-compatible air sealing products because we’ve installed Demilec foam for years and know how it behaves. The relationship gives you honest parts guidance without the manufacturer’s markup.
DIY or Call Us?
There’s a safe middle path here. You can visually inspect your attic for obvious gaps, feel for drafts around ceiling fixtures, and check the attic hatch for a proper seal. Those checks cost nothing and tell you whether the problem is isolated or widespread.
What we don’t recommend is buying a case of canned foam and sealing everything you see. Attic air sealing is low-risk compared to, say, a garage door spring, but the products still need to cure correctly and bond to cured Demilec foam. In a Houston attic, a bad DIY sealant job fails within months because the heat cycling breaks uncured or incompatible material. You might also accidentally seal a gap that needs to breathe, like a soffit vent, and create a moisture problem nobody wants in a Houston attic.
If you want to check it yourself first, that’s fine. If you want it matched to your Demilec system and done once, call (430) 226-1334. We’ll give you an honest answer either way.
FAQs
In Houston’s climate, properly installed Demilec-compatible air sealing should last 10 to 15 years before noticeable degradation. The heat and humidity overhead accelerate material aging compared to cooler climates, but the failure point is usually at the seams and penetrations, not the foam itself.
Yes, in many cases. If the failure is limited to gaps around recessed lights, plumbing vents, or the attic hatch, a targeted repair often solves it. If the foam has pulled away from framing across large sections of the roof deck, replacement is usually the more cost-effective long-term answer. Call (430) 226-1334 and we’ll tell you which situation you’re in.
Most Demilec attic air sealing jobs take one day, typically 4 to 7 hours depending on attic size and how many penetrations need work. We’ll schedule around your family’s routine, and our crew uses quiet tools when children are sleeping.
We typically run Houston jobs with the materials loaded the same day, but we’re not a parts warehouse. You’ll never wait two weeks for a part to ship from a distributor. When we schedule your job, we order exactly what your attic needs, so the work happens in one visit.
Written by Neil Barron, Owner, Thistledown Insulation Houston at Thistledown Insulation Houston, serving Houston and nearby areas.