Demilec Attic Air Sealing: The Fort Worth Owner’s Guide
Demilec attic air sealing in Fort Worth typically runs $1,400 to $3,200 installed, depending on attic square footage and how much of the existing seal has failed. We stock Demilec-compatible air seal kits and foam on our trucks, and most Fort Worth jobs are completed same-day. Here’s the reality we see on a lot of service calls: homeowners notice a musty smell, a dusty upstairs, or an AC bill that jumped $60 or more in a month. They crawl up to check, and what they find is air seal foam that’s cracked, pulled away from the framing, or just never covered the gaps it should have. That’s the moment they call us.
If you’re reading this page, you probably already know your Demilec product isn’t holding. Good. Let’s get it fixed properly. Chase Whitaker and our crew at Laurel Attic Insulation Fort Worth deal with this specific repair all year, and we’ll walk you through exactly what you’re looking at.
Which Demilec Models This Applies To
Demilec makes two main product lines that show up in Fort Worth attics: the Sealection 500 open-cell spray foam and the Heatlok HFO closed-cell series. Both are used for attic air sealing, but they fail differently, and the repair approach isn’t identical. Sealection 500 is the softer, open-cell foam you see sealing rim joists, top plates, and around penetrations like plumbing vents and ceiling light boxes. Heatlok HFO is the denser closed-cell foam more common on roof decks and gable ends.
Here’s the compatibility gotcha most homeowners don’t know: air seal touch-up foam has to match the original foam’s expansion characteristics. Open-cell foam needs a sealant that expands aggressively to fill gaps but stays breathable. Closed-cell needs a denser, moisture-barrier product. Using the wrong one means the repair cracks again within a season. We match the foam to your existing Demilec product, not whatever tube was cheapest at the home center.
Identifying your model: look for the Demilec label on any remaining foam, usually stamped on the substrate near the original application. If the label is gone, a fingernail press into the foam tells us most of what we need. Spongy and soft = open-cell Sealection. Firm and rigid = closed-cell Heatlok. On the OEM-versus-aftermarket question, we’re direct about it: for Demilec products, we use Demilec-compatible or equal-spec sealants, because the foam chemistry matters. A generic can foam will technically fill a gap for a while, but Fort Worth’s attic temperature swings between 40°F winter mornings and 140°F summer afternoons beat the life out of generic products fast.
Signs Your Demilec Attic Air Sealing Is Failing
- Dusty upstairs rooms despite no obvious source. Air seal foam that’s shrunk or pulled away lets filtered attic dust blow down through light fixtures, outlet plates, and trim gaps. You’ll see fine gray dust on window sills and dressers.
- Upstairs bedrooms are 8-10 degrees warmer than downstairs in summer. That’s attic air dumping into the conditioned space through unsealed top plates and penetrations. Your AC works harder, and the upstairs never quite catches up by bedtime.
- A musty or stale smell in the upstairs hallway. Attic air isn’t just hot. It carries whatever’s up there: blown-in fiberglass dust, old rodent droppings, humidity. Failed air seal means that cocktail is seeping down.
- Visible gaps where foam has cracked or separated from drywall or framing. Demilec open-cell foam especially can shrink over 8-12 years in extreme heat cycles. If you can push a putty knife between the foam and the wood, it’s no longer sealing.
- Your energy bill spiked without a rate change or new appliances. A failed 6-foot run of top plate seal can add 10-15% to cooling costs in July in Fort Worth. We see this with older ranch homes near the TCU area that were foamed once in the early 2010s and never touched again.
Replacement Cost & What’s Included
Let’s put straight numbers on it. For a typical 1,800 to 2,400 square foot Fort Worth home, Demilec attic air sealing replacement runs $1,400 to $3,200 installed. The range depends on three things: how many linear feet of top plate and penetration sealing need redoing, whether we’re spot-treating failed areas or doing the full perimeter, and accessibility. Attics with deep blown-in insulation covering the top plates take longer, because we have to rake material aside, seal, and put it back properly.
| Scope | Typical Fort Worth Installed Range |
|---|---|
| Spot repair (under 50 linear feet) | $1,400 – $1,800 |
| Full perimeter top plate + penetrations | $1,900 – $2,600 |
| Full air seal + ridge/soffit gap correction | $2,600 – $3,200 |
Every quote we write includes the full price before work starts, in writing. No discovery fees, no surprise line items at the end. The labor, the foam, the cleanup, and the written 365-Day Done Right Promise are all on the invoice you can pay from a link. If the seal fails within a year, we come back and fix it at no charge. That’s not a wink-and-nod guarantee. It’s printed on the work order.
DIY or Call Us?
Here’s the honest split. The safe things you can check yourself: visible cracks in existing foam, gaps where the foam has pulled away from wood, and whether you can feel air moving around top plate areas with a careful walk through the attic. Those checks are fine, and a homeowner can absolutely do them. Where DIY goes wrong is the actual application. Attic air seal foam in the wrong hands creates three problems: the wrong product choice (open-cell vs closed-cell chemistry, as covered above), overspray that’s nearly impossible to remove from decking or stored items, and missed gaps that look sealed from eye level but aren’t from the underside. You’ll pay for the foam, spend a Saturday in a 130-degree Fort Worth attic, and still end up with the same problems in six months.
Call us at (817) 730-5474. We’re in and out same day on most Demilec air seal repairs, and you’ll have a written price before anything starts.
FAQs
Properly applied Demilec attic air sealing should hold for 15 to 20 years in Fort Worth’s climate, but we often see failure at the 8-12 year mark when the original application was thin or the attic ventilation wasn’t adequate. Heat and humidity cycling is the main killer, and Fort Worth has both in spades. Call (817) 730-5474 if you suspect premature failure; we’ll assess it honestly before recommending anything.
Most of the time it can be repaired in sections. If the failure is isolated to top plates or a few penetrations, we spot-treat the failed areas and leave intact foam alone. Full replacement only makes sense when the original application was too thin everywhere or the foam has separated from the substrate across most of the attic. We’ll tell you which applies after a free assessment, and we won’t sell you work you don’t need.
A typical Fort Worth attic air sealing repair takes 3 to 6 hours on site, and we complete most jobs same-day. Larger full-perimeter jobs can run into a second day if the attic is deep with old insulation. You’ll get a live arrival time before we show up, and photo updates while the work is happening.
Yes. Our Fort Worth trucks carry Demilec-compatible sealants and matching foam for both open-cell and closed-cell applications, plus Reflectix products for radiant barrier and HVAC gap work. We’re not affiliated with Demilec, but we use their compatible products because the foam chemistry matches what’s already in your attic, and mismatched chemistry is the fastest way to a repeat failure.
Call for a Free Estimate
If you’re in Fort Worth and your Demilec attic air sealing is failing, call us at (817) 730-5474. A live person answers, 24/7. We’ll schedule a time, show up when we say we will, and hand you a written price before anything gets sprayed. Chase grew up in Los Angeles and learned this trade at LATTC before working Fort Worth attics for years, and he’ll tell you the same thing on the phone that he will in person: good insulation shouldn’t be a mystery, let me just show you the numbers.
Written by Chase Whitaker, Owner, Laurel Attic Insulation Fort Worth at Laurel Attic Insulation Fort Worth, serving Fort Worth and nearby areas.