Demilec Vapor Barrier Installation Nationwide

Demilec Vapor Barrier Installation: The Round Rock Owner’s Guide

Demilec vapor barrier installation in Round Rock typically runs $2,400-$4,800 for a full crawl space or attic application, depending on square footage and whether we’re sealing over bare earth or replacing a failed existing membrane. We stock Demilec-compatible 10-mil and 15-mil reinforced polyethylene on every truck, and most jobs in Round Rock’s 78664, 78665, and 78681 ZIPs start same-day or next-day. Most homeowners discover the problem after spotting condensation droplets on ductwork, catching a musty smell that worsens after rain, or noticing their HVAC runs longer than it used to - all signs that moisture is migrating through a compromised or missing vapor barrier.

Call (737) 259-7528

Which Demilec Models This Applies To

Demilec doesn’t sell vapor barriers as standalone branded SKUs the way they market their Heatlok or Sealection spray foam lines. What Round Rock homeowners usually mean by “Demilec vapor barrier” is the reinforced polyethylene membrane installed as part of a Demilec-supervised crawl space or attic encapsulation system, often paired with their closed-cell foam on rim joists. The compatibility question comes down to mil thickness and reinforcement pattern, not a model number.

We verify what you’ve got in three ways: the stamped mil rating on the membrane edge (10-mil is standard for crawl floors, 15-mil for walls and high-traffic areas), the woven fiber grid pattern visible when held to light, and whether the existing barrier was heat-seamed or taped at overlaps. Demilec-specified jobs in this region typically used 10-mil cross-woven with a 6-inch overlap seam. Aftermarket equivalents from Reef Industries or Stego wrap perform identically if they match those specs, and we carry both. Topside Attic Insulation Round Rock is an independent service provider, not affiliated with Demilec.

One gotcha in older Round Rock builds, especially in neighborhoods like Old Town and Meadow Lake built during the 1990s construction boom: the original “vapor barrier” was sometimes just 6-mil untaped painter’s plastic that disintegrates in five to seven years. It carries no Demilec marking because it was never part of a proper system. We see this misidentified constantly.

Signs Your Demilec Vapor Barrier Installation Is Failing

• Condensation on ductwork or joists. When the barrier tears or pulls away from walls, ground moisture rises and condenses on cooler surfaces. In Round Rock’s clay-heavy soils, this accelerates after spring rains when the water table sits higher.
• Musty odor that spikes after weather changes. A intact barrier blocks soil gases and evaporating moisture. Once compromised, the crawl space becomes a humidity reservoir. The smell often hits hardest in September and October when outside air cools but soil temperatures stay elevated.
• Increased HVAC runtime with no thermostat change. Ductwork in a damp crawl space loses efficiency through latent heat load - your system works harder to dehumidify air that’s already wet. We’ve measured supply ducts in unsealed Round Rock crawls running 8-12 degrees below design output.
• Visible mold or efflorescence on foundation walls. White powdery deposits mean moisture is migrating through concrete and evaporating at the surface. The barrier’s job is to stop that migration at the soil line; efflorescence above the barrier line means it’s breached or never sealed to the wall.
• Sagging or pooled areas in the membrane. Standing water on top of the barrier indicates either a puncture letting groundwater up, or poor site grading sending runoff underneath. In Round Rock’s flash-flood-prone watersheds, this is often the first visible failure mode after heavy events.

Replacement Cost & What’s Included

For a typical 1,200-2,000 square foot crawl in Round Rock, full vapor barrier replacement runs $2,400-$3,800. Smaller utility crawls (400-800 square feet) start around $1,800. Wall wrapping or complex geometries with multiple piers push toward $4,800. The range reflects three variables: whether we’re removing and hauling old material, how much tape and seam work the geometry demands, and whether the job includes complementary air sealing at rim joists.

Every quote under Haven Standard Clause 1 is flat-priced, written, and delivered before work starts. The scope includes: removal and disposal of existing barrier, surface prep and debris clearing, installation of new reinforced polyethylene with heat-sealed or double-taped overlaps, mechanical fastening to foundation walls, and sealing around penetrations. We also deliver a Documented Photo Record of the completed space and, if rim joist sealing is included, before-and-after blower-door numbers so you can verify the air-sealing result. The 365-Day Done Right Promise covers all work. Materials come from our standard supplier line including Demilec, Owens Corning, and Reef Industries - no proprietary lock-in.

DIY or Call Us?

There’s no high-tension danger in vapor barrier work the way there is with garage door springs or gas lines. The honest limit is physical access and attention to detail. A homeowner can safely check: whether the barrier is still taped at walls, whether standing water is present, and whether obvious punctures or rodent damage exist. Mark these with tape for reference.

Where DIY goes wrong is in the seams. Overlaps need six inches minimum, taped or heat-sealed on both sides, with no wrinkles that create channels for soil gas. Wall fastening must run continuous within six inches of grade. We’ve re-done four homeowner installs in Round Rock this year alone where the membrane looked fine but was passing moisture at untaped overlaps. The material is cheap; the labor to do it twice is not. If your crawl has active water intrusion, electrical runs below grade, or mold coverage exceeding ten square feet, call (737) 259-7528. We’ll read your situation with you and give a written price before any work starts.

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