Demilec Crawl Space Encapsulation & Vapor Barrier Nationwide

Demilec Crawl Space Encapsulation & Vapor Barrier in San Marcos: What to Know First

We provide independent Demilec crawl space encapsulation and vapor barrier service in San Marcos, with most jobs completed in one day and a written price delivered before any work starts. Most Demilec crawl space systems we encounter in the San Marcos area run between $2,800 and $6,500 depending on whether we’re addressing a failing Demilec 500 open-cell application or a full Demilec Heatlok HFO High Lift encapsulation with vapor barrier replacement. This page is for homeowners who’ve found Demilec spray foam in their crawl space and need to know whether it’s salvageable, what it’ll cost to fix, and who can do it without voiding what’s left of the material warranty. Call (737) 337-8049 for a free estimate with a written scope.

Call (737) 337-8049

How Demilec Products Fail - and How We Fix Them

• Demilec 500 open-cell hydroscopic failure in crawl spaces. The 500 series is an open-cell water-blown foam that absorbs moisture like a sponge when the vapor barrier above it fails. In San Marcos, we see this most in homes built between 2012 and 2018 near the Blanco River corridor where seasonal humidity swings hit 40% in a single day. We remove the saturated foam, install a new 6-mil minimum vapor barrier with sealed seams, then replace with closed-cell Demilec Heatlok XT if re-insulation is needed.
• Demilec Heatlok HFO High Lift delamination from crawl space rim joists. The HFO blowing agent in this high-lift closed-cell product can shrink 3-5% during cure if applied over cold, damp wood in a vented crawl space. We find this in San Marcos homes with original foundation vents still open year-round. Our fix: complete removal of delaminated sections, thermal imaging to locate remaining gaps, then reapplication with substrate conditioning and a continuous vapor barrier seal.
• Demilec SEALECTION AgriBalance UV degradation in partial encapsulations. This agricultural-grade formulation degrades when exposed to light through crawl space access doors or missing vent covers. The surface chalks and loses its closed-cell structure. We replace with a UV-stable vapor barrier overlay or full encapsulation depending on access frequency, and we always specify white or reflective barrier material in San Marcos where crawl space temps can exceed 95°F in August.
• Demilec 1801/1802 legacy product off-gassing in conditioned crawl conversions. These early water-blown formulations can emit trace amines if the crawl space is later sealed for HVAC efficiency. We test with a photoionization detector - a handheld air quality meter - then either encapsulate with an aluminized vapor barrier barrier or remove and replace with Heatlok XT, depending on concentration and homeowner sensitivity.
• Vapor barrier seam failure over Demilec spray foam. Even good foam fails when the polyethylene barrier above it separates at seams due to San Marcos clay soil expansion shifting the crawl space floor. We install barriers with 12-inch overlap, double-sided butyl tape, and mechanical fastening at stress points - not the 6-inch single-tape method we find on most original installations.

Our Demilec Crawl Space Encapsulation & Vapor Barrier Process

1. 1
   Call and scope. A live person answers, schedules a visit, and Wes Okafor or a senior tech arrives with a moisture meter, thermal camera, and blower-door fan if the crawl space connects to conditioned space.
2. 2
   Written price before any work starts. We document what we found - foam condition, vapor barrier integrity, moisture source - and deliver a flat price with scope and warranty in writing. No work starts without it. Haven Standard Clause 1.
3. 3
   Material decision: OEM Demilec vs. quality aftermarket. We stock Demilec Heatlok XT and Heatlok HFO for warranty-continuous repairs. For full replacements where Demilec warranty has expired, we may specify Owens Corning Foamular or Johns Manville CI Max as the vapor barrier substrate - always disclosed in writing.
4. 4
   Removal, prep, and installation. Saturated or failed foam comes out. Wood substrate dries to 19% moisture content or below - we check with a pin meter. New vapor barrier goes down with sealed seams and mechanical fastening. Foam, if needed, is applied to manufacturer thickness.
5. 5
   Test and document. Where the crawl space communicates with living space, we run a blower-door test - a pressurization reading that shows, in one number, how much air your building envelope is losing - before and after sealing. You get a single printed page with the air-changes-per-hour figure. Photos of every stage go in your Documented Photo Record.
6. 6
   365-Day Done Right Promise closeout. Written warranty, final walk, and our promise: if it’s not done right, we make it right.

Before

After

What Demilec Crawl Space Encapsulation & Vapor Barrier Costs in San Marcos

These are real numbers for San Marcos - not bait-and-switch ranges. We also service Reflectix radiant barrier systems if your crawl space has a hybrid insulation setup. Every estimate is free, every price is written, and every job gets the Documented Photo Record. Call (737) 337-8049.

Why San Marcos Homeowners Call Topside Attic Insulation San Marcos for Demilec Work

We’ve sealed and insulated over 9,000 homes since 2016, and we’ve learned that crawl spaces in San Marcos fail predictably - clay soil movement, humidity swings, and contractors who blew foam without checking what was underneath. The R-value tells you how slow heat moves through the material - the blower-door number tells you whether any of that matters. We publish both. Our 365-Day Done Right Promise applies to every job, our technicians are background-checked and uniformed, and a live person answers calls 24/7. We’re an independent Demilec service provider - not affiliated with or authorized by Demilec - which means we choose the right fix for your situation, not the one that protects a manufacturer relationship.

FAQs