Demilec Crawl Space Encapsulation Nationwide

Demilec Crawl Space Encapsulation: The Cedar Park Owner’s Guide

Demilec crawl space encapsulation repair in Cedar Park typically runs $2,800-$5,400 for a full system replacement, and we stock Demilec-compatible vapor barriers, seam tape, and drainage matting on our trucks for same-day starts. Most Cedar Park homeowners notice the problem first as a musty smell returning after months of dryness, or they spot white mineral deposits - efflorescence - blooming on the block walls where the poly sheeting has pulled loose. We see this pattern constantly in the older ranch homes near Buttercup Creek and the 1980s builds along Cypress Creek Road, where seasonal clay expansion shifts the ground and stresses the membrane seams.

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Which Demilec Models This Applies To

Demilec’s crawl space line centers on the Heatlok HFO High Lift series for closed-cell spray foam perimeter band joists, paired with their Demilec Vapor Shield reinforced polyethylene for ground cover. The critical compatibility check is the mil rating stamped on the poly edge: Demilec ships 12-mil and 20-mil variants, and mixing them on the same job voids the manufacturer’s seam warranty because the tape adhesive cures at different rates. We’ve found 20-mil in the newer Leander builds west of Cedar Park, while the 12-mil shows up in original 1990s installations from the Anderson Mill area.

To identify your system, look for the yellow Demilec batch tag on the foam applicator box - usually tucked behind the HVAC plenum - or the black-ink stamp on the poly overlap seam every 6 feet. The OEM vapor barrier carries a Demilec logo emboss; aftermarket equivalents from Stego or Crawlspace Depot match the 20-mil spec but lack the exact dielectric seam tape formula Demilec specifies for foam-to-poly adhesion. We stock both. Most Cedar Park jobs don’t need OEM purity; they need the right mil, the right tape, and a crew that won’t staple through the membrane where it crosses the footing.

Signs Your Demilec Crawl Space Encapsulation Is Failing

• Musty odor returning in humid months. The vapor barrier has torn at a seam or the tape has delaminated, letting soil moisture evaporate into the crawl space air. In Cedar Park, this hits hardest in May and September when the Gulf moisture pushes in and the clay soils hold water against the foundation.
• White powder on block walls. That’s efflorescence - mineral salts left behind when water vapor migrates through concrete, condenses, and evaporates. It means your ground cover or wall foam has a gap somewhere, often where the poly meets the pier column.
• Sagging insulation above the crawl space. When relative humidity climbs above 70% in the crawl, fiberglass batts absorb moisture and the weight pulls them from the subfloor. We’ve pulled down dripping batts in Cedar Park homes where the Demilec vapor barrier had a single 4-inch slit from a previous plumber’s crawl.
• Increased HVAC runtime with no temperature change. Ductwork in a damp crawl space loses efficiency through latent heat load - the system works harder to dehumidify air it’s already conditioned. Your blower-door number won’t show this; it’s a distribution problem, not an envelope leak.
• Pest activity or rodent trails on the poly. Torn vapor barrier creates access points. In the brushy lots near Cedar Park’s northwest edge, we’ve found raccoon paw prints on the white poly where a seam failed and the animal used the crawl as a highway.

Replacement Cost & What’s Included

Most full Demilec crawl space encapsulation replacements in Cedar Park run $2,800-$5,400 installed. The low end covers a clean 1,200-square-foot crawl with straightforward access, new 12-mil poly, seam tape, and perimeter foam touch-up. The high end hits 2,500+ square feet with drainage matting install, sump pump integration, and removal of degraded old foam that has pulled from the band joist.

What drives the spread: access height (less than 18 inches requires crew rotation), existing mold remediation needs, and whether the foundation walls need mechanical fastening for the poly termination bar. Every job gets a written price before work starts - Haven Standard Clause 1 - and the 365-Day Done Right Promise covers labor and materials. We also publish before-and-after blower-door readings when the encapsulation ties into a full envelope job, so you can see the actual air-sealing improvement, not just a drier crawl.

DIY or Call Us?

There’s a safe middle ground here. A homeowner can check the crawl space humidity with a $15 sensor, photograph any poly tears or tape gaps, and verify the sump pump runs - that’s useful intelligence for any contractor. But installing vapor barrier correctly in a Cedar Park crawl means sealing to a 0.1-perm rating or lower, and that requires overlapping seams by 12 inches minimum, taping every joint with pressure-sensitive acrylic adhesive rated for damp substrates, and terminating the poly on the wall 6 inches above outside grade with a mechanical fastener every 12 inches. Miss any of that, and you’ve paid for material that traps moisture instead of blocking it.

The bigger risk: disturbing old Demilec foam without respiratory protection. Pre-2017 formulations may contain isocyanate residues that aerosolize when cut. We carry forced-air respirators and negative-air machines for this reason. If your crawl has any foam older than 2018, don’t cut it yourself. Call (737) 245-6428 and we’ll assess it with proper containment. Seal the leaks first. Then insulate. The order matters more than the product.

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