Demilec Crawl Space Encapsulation & Vapor Barrier Nationwide

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

We provide independent Demilec crawl space encapsulation and vapor barrier service in Seguin, typically completing most jobs within one to two business days after diagnosis. Most crawl space encapsulation and vapor barrier jobs for Demilec systems in the Seguin area run between $2,800 and $5,400 depending on square footage, existing moisture damage, and whether the foundation requires full perimeter sealing. We are an independent Demilec service provider, not affiliated with or authorized by Demilec, which means we work with the materials already in your home and recommend what actually fixes the problem rather than what a manufacturer catalog suggests.

Call (830) 549-6646

This page is for Seguin homeowners who have Demilec insulation products in their crawl space and are seeing moisture issues, musty odors, or temperature inconsistencies in their floors. If that describes your situation, call us at (830) 549-6646. We will schedule a free inspection, give you a written price before any work starts, and leave you with a documented photo record and, where applicable, before-and-after blower-door numbers.

How Demilec Products Fail - and How We Fix Them

• Demilec Heatlok HFO Pro applied to crawl space rim joists loses adhesion in Seguin’s spring humidity swings. The Hill Country’s rapid temperature shifts between March and June create condensation cycles that break the foam-to-wood bond at the rim joist. We remove the failed sections, mechanically abrade the substrate, and reapply only after installing a proper vapor barrier on the crawl floor to stabilize the moisture load.
• Demilec Sealection 500 in vented crawl spaces develops shrinkage gaps after 7-10 years. This open-cell product was commonly used in Seguin builds from 2012-2018 and continues to off-gas and contract in unconditioned spaces. We do not simply spray over the gaps. We cut back to sound foam, seal the perimeter with closed-cell Demilec Heatlok XT at 2-inch minimum thickness, and verify with a blower-door test that the rim joist plane is actually airtight.
• Demilec 500 open-cell on crawl space ducts absorbs ground moisture and sags. When this product is applied directly to flex ductwork in a vented crawl, it acts as a sponge during Seguin’s heavy rain periods. We remove the saturated foam, replace compromised duct insulation with properly sealed reflective duct wrap, and encapsulate the crawl space so the problem does not repeat.
• Demilec Heatlok XT closed-cell applied too thin over rubble foundations develops thermal bridging. Seguin has extensive limestone and caliche substrate, and crews working fast sometimes spray 1 inch where 3 inches is needed for the rated R-value. We measure existing thickness with a pin gauge, mark deficient areas, and build to proper depth in lifts so the foam cures without voids.
• Demilec spray foam in crawl spaces with active groundwater lacks proper drainage prep. No foam product survives standing water. In neighborhoods near the Guadalupe River floodplain, we have found Demilec installations that were essentially applied over mud. We install interior perimeter drains and a 20-mil reinforced vapor barrier before touching any foam, because sealing a wet crawl space traps moisture against the structure.

Our Demilec Crawl Space Encapsulation & Vapor Barrier Process

1. 1
   Inspection and moisture mapping. We enter the crawl space with humidity loggers, a thermal camera, and a pinless moisture meter. We document every Demilec product line present, its condition, and any signs of failure. You get photos before we touch anything.
2. 2
   Blower-door test if the crawl connects to conditioned space. This pressurization reading shows, in one number, how much air your building envelope is losing through the crawl plane. In Seguin’s older homes near downtown, this is often the single largest leak path.
3. 3
   Written scope and price. We specify whether we are repairing existing Demilec foam, removing and replacing it, or encapsulating over it. We also note if OEM Demilec material or equivalent closed-cell from another manufacturer is the better choice for your specific failure mode.
4. 4
   Drainage and vapor barrier first. We install a 20-mil reinforced polyethylene barrier, sealed at seams and walls, before any foam work. In Seguin’s clay-heavy soils, we may add a sump pit if hydrostatic pressure is present.
5. 5
   Foam repair or replacement with documented thickness. We apply in controlled lifts, measure with a pin gauge, and photograph coverage. The report goes home with you - the numbers do the talking.
6. 6
   Final blower-door test and documentation. We run the test again, hand you the pre- and post-installation report with actual ACH50 numbers, and activate your 365-Day Done Right Promise in writing.

Before

After

What Demilec Crawl Space Encapsulation & Vapor Barrier Costs in Seguin

These are the ranges we see on actual Seguin jobs, not national averages. A 1,200-square-foot crawl on pier-and-beam near McQueeney with good access and no drainage issues typically lands in the lower half. A 2,400-square-foot crawl with failed Demilec Sealection 500 on ducts, groundwater intrusion, and tight clearance near the Guadalupe River corridor runs higher. We give you a flat written price before any work starts - no allowances, no surprises. Call (830) 549-6646 for a free inspection and exact quote.

Why Seguin Homeowners Call Topside Attic Insulation Seguin for Demilec Work

We have worked on Demilec products in Seguin long enough to know which batches from which years had adhesion issues, and which application thicknesses actually perform in this climate versus what the spec sheet claims. Wes Okafor learned the building science side of this trade at Triton College in River Grove, IL, and that foundation matters when you are diagnosing why a crawl space is still damp after someone already “fixed” it.

We also service Reflectix and other major brands, so if your crawl space has a mix of products or if Demilec is not the right solution for your specific condition, we will tell you straight. Every job gets a written scope, a written price, and a documented photo record. The 365-Day Done Right Promise applies to all completed work. Calls are answered by a live person 24/7, and we serve established Seguin neighborhoods from near Guadalupe Regional Medical Center out to the Hill Country edge.

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