Demilec Attic Air Sealing Nationwide

Demilec Attic Air Sealing: The Pflugerville Owner’s Guide

Demilec-compatible attic air sealing in Pflugerville typically runs $1,800-$3,400 for a complete top-plate, penetration, and can-light seal on a 1,800-2,800 square foot home, and we stock the Demilec APX and Heatlok HFO spray foam systems on our trucks for same-day starts. Most homeowners in Pflugerville’s Stone Hill Town Center corridor and Blackhawk neighborhoods call us after a summer energy bill spikes 30% or more, or after a home energy audit flags conditioned air bleeding into the attic through gaps the original builder never sealed.

Call (737) 259-8352

Which Demilec Models This Applies To

We work with Demilec’s two primary residential spray foam lines: the APX series (open-cell, 0.5 lb/ft³ density, typically used for attic floor and knee-wall applications) and the Heatlok HFO series (closed-cell, 2.0 lb/ft³ density, used for rim joists and structural sealing in conditioned attics). The part number you’re looking for lives on the drum label - APX 500, APX 1000, Heatlok HFO Pro, or Heatlok XT. If your previous installer left documentation, check for a “Demilec” header with a lot code starting in “TX-” for regional distribution.

Here’s the compatibility gotcha we see weekly in Pflugerville: Demilec’s open-cell and closed-cell products are not interchangeable for the same application. Open-cell APX requires a vapor retarder coating in our climate zone (IECC Zone 2, hot-humid), while Heatlok HFO does not. We’ve found homes in Pflugerville’s Windermere and Avalon subdivisions where a previous contractor sprayed open-cell against the roof deck without the required coating, and the foam degraded from the underside within four years. We source OEM Demilec material through the regional distributor in Austin; we do not use bucket-shop equivalents that claim “compatible” density but off-gas differently and void any remaining warranty coverage.

Topside Attic Insulation Pflugerville is an independent service provider - we are not affiliated with Demilec.

Signs Your Demilec Attic Air Sealing Is Failing

• Spiking summer cooling bills with no thermostat change. The spray foam was supposed to create an air barrier at the attic floor or roof deck; when it shrinks, pulls from framing, or was applied too thin at the top plates, conditioned air escapes at 120°F attic temperatures and your AC runs overtime. We see this most in Pflugerville homes built 2015-2019 where the original foam was applied below the 1-inch minimum pass thickness.
• Hot second-floor rooms that were comfortable when the house was new. Demilec APX open-cell can settle 5-10% over the first two years; if the installer didn’t account for this in the original pass count, gaps open at wall-to-ceiling junctions. The bedroom over the garage in a two-story plan is usually the first to complain.
• Dust streaks on ceiling drywall near can lights or registers. These are thermal tracking marks - air moving through the cavity carries attic dust and deposits it where the drywall is cold from air leakage. In Pflugerville’s windy spring months, a failed air seal pulls more particulate than in still summer air.
• Musty odor in the attic or upper floor after rain. Heatlok HFO closed-cell is also your moisture barrier; if it was mechanically damaged during a later HVAC or rodent removal job, humid outdoor air reaches the sheathing. We’ve found this in attics where a cable installer crawled across the foam and cracked the seal without reporting it.
• Blower-door test shows CFM50 above 2,500 on a home under 3,000 sq ft. A well-sealed home of that size in Pflugerville should read closer to 1,500-2,000 CFM50 depending on stories and fireplace count. If your number climbed back toward the pre-seal figure, the foam has failed or was never fully continuous.

Before

After

Replacement Cost & What’s Included

What drives the range: attic accessibility (scuttle vs. pull-down stairs vs. framed access), existing foam condition (spot-repairable vs. full removal required), and whether we need to coordinate with an electrician for live can-light de-rating. Every job gets a written price before any work starts - Haven Standard Clause 1 - and includes our Documented Photo Record. Applicable jobs receive before-and-after blower-door numbers so you can verify the air-sealing result in CFM50, not in a handshake. The 365-Day Done Right Promise covers all completed work.

DIY or Call Us?

What you can safely check: walk your attic with a flashlight and look for visible gaps where foam has pulled from framing, yellowed or crumbled sections, or areas where the foam was never sprayed (common at the eaves over exterior walls). Take photos. If you have a previous energy audit or blower-door report, compare the CFM50 number to your current feel.

Where DIY goes wrong: spray foam application requires controlled temperature, humidity, and substrate conditions that a Pflugerville attic rarely provides in summer without active ventilation. More critically, the two-component chemistry in Demilec’s APX and Heatlok lines is an isocyanate-based system - improper mixing ratios or inadequate PPE exposure can trigger respiratory sensitization that is permanent. We do not recommend homeowner application. Our technicians are trained in the manufacturer’s installation parameters, and we carry the full respirator and ventilation setup on every truck.

If you’re seeing the symptoms above, call (737) 259-8352. We’ll read your existing documentation with you, including any competing quote, at no charge.

FAQs