Demilec Crawl Space Encapsulation Nationwide

Demilec Crawl Space Encapsulation: The New Braunfels Owner’s Guide

Demilec crawl space encapsulation repair in New Braunfels typically runs $1,800-$4,200 for a full vapor barrier and seal replacement, with most jobs completed in a single day. We stock Demilec-compatible 10-mil and 16-mil reinforced polyethylene barriers, seam tape, and closed-cell spray foam for rim joist sealing on our trucks, and we can usually schedule within 48 hours. Most homeowners discover a failure when their crawl space starts smelling musty in summer, their floors feel cold despite the heater running, or they spot condensation beading on the underside of their subfloor during a routine HVAC filter change.

Call (830) 243-6352

Which Demilec Models This Applies To

Demilec does not sell crawl space encapsulation as a branded “system” with model numbers the way they organize their spray foam rigs. What you’re looking for is the Demilec-sourced material spec: typically a woven-reinforced polyethylene vapor barrier, often paired with Demilec Heatlok HFO or Heatlok XT closed-cell foam for rim joist and sill plate sealing. The compatibility gotcha in New Braunfels is that some installers from the 2015-2019 rush used 6-mil non-reinforced sheeting that tears on our limestone substrate during routine pest inspections. If your barrier has “Demilec” printed on the tape or the foam tags read Heatlok series, we can match it.

Identify what you have in three steps. First, check the rim joist foam for a Demilec lot tag - small, white, usually stuck to the foam surface near the sill plate. Second, measure your vapor barrier thickness with a caliper or by feeling for a woven grid pattern; 6-mil tears easily, 10-mil and 16-mil have a crosshatch texture you can see when backlit. Third, note whether your seams are taped with butyl-backed tape or just overlapped. We stock both OEM Demilec-compatible materials and quality aftermarket equivalents from Johns Manville and Owens Corning. For most New Braunfels homes, the aftermarket 16-mil woven barrier outperforms the original 10-mil at a lower per-square-foot cost, and we warranty the install either way.

Signs Your Demilec Crawl Space Encapsulation Is Failing

• Musty odors rising through floor registers. When the vapor barrier separates at seams or tears on sharp limestone, ground moisture evaporates into the crawl space air. That humid air gets drawn up through duct chases and floor gaps by the stack effect - the natural upward pull of warm air in a house - and smells hit you when the HVAC runs.
• Cold floors in winter despite adequate attic insulation. A compromised barrier lets evaporative cooling work against your subfloor. In New Braunfels, where winter nights dip into the 30s and slab homes have minimal perimeter insulation, a failed seal can drop floor surface temperature 8-12 degrees below room air.
• Condensation on HVAC ducts and plumbing lines. When relative humidity in the crawl space climbs above 65%, any surface below the dew point - cold water pipes, metal ductwork - beads with moisture. We see this most in riverside neighborhoods like those off River Road, where water tables sit higher and seasonal humidity swings are sharper.
• Pest activity or rodent trails on the barrier surface. Torn polyethylene creates nesting material and access routes. A proper 16-mil woven barrier with sealed seams eliminates those pathways; 6-mil sheeting might as well be a welcome mat after one season.
• Visible mold or efflorescence on foundation walls. White, powdery efflorescence is mineral salt left behind as moisture moves through block walls. It means your barrier isn’t stopping soil moisture migration, and mold follows within one to two seasons in our climate.

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Replacement Cost & What’s Included

Most full Demilec-compatible crawl space encapsulation replacements in New Braunfels run $1,800-$4,200 installed, with partial repairs starting around $850. The range depends on three factors: crawl space square footage, whether we need to remove and dispose of failed material, and how much rim joist foam has degraded or been disturbed by prior pest work.

Here’s how that breaks down on a typical 1,200-square-foot crawl:

Every job gets a Written Price Before Any Work Starts under Haven Standard Clause 1 - flat price, written scope, written warranty before anyone lifts a tool. We also deliver a Documented Photo Record and, on jobs where air sealing is part of the scope, before-and-after blower-door readings so you can verify the performance change. The 365-Day Done Right Promise applies to all completed work.

DIY or Call Us?

There’s safe checking, and then there’s work that belongs to someone with a respirator and a headlamp.

What you can do: verify your barrier thickness with a tape measure and flashlight, photograph any tears or separated seams for our review, and check that your crawl space vents are closed if you have a conditioned crawl. Note any musty smells or cold spots - that’s useful intel.

Where DIY goes wrong: crawling in a 24-inch clearance space with sharp limestone edges, handling closed-cell foam chemicals that require respiratory protection, and sealing seams without proper surface prep so they fail again in 18 months. The 16-mil barrier is heavy - roughly 0.35 pounds per square foot - and awkward to position in tight quarters. More critically, if your rim joist foam is degrading, disturbing it without proper containment can release particulates you don’t want in your lungs. We’ve re-done three homeowner attempts in New Braunfels in the past two years alone, and the redo always costs more than calling first.

Call (830) 243-6352 and we’ll walk through what you’re seeing. Estimates are free, and we stock Demilec-compatible materials on the truck.

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