What encapsulation actually is
A crawl space "encapsulation" in our market means four things, in order:
- 20-mil reinforced vapor barrier across all earthen surfaces, walls, and pier bases — mechanically fastened, seams overlapped and taped
- Perimeter sealing — every vent closed (or covered with rigid foam), every penetration sealed
- Drainage where moisture has been entering — interior or perimeter french drain to daylight or sump basin
- Continuous dehumidifier sized to the crawl's cubic footage, on its own circuit, draining to the sump basin or a condensate pump
Sometimes a fifth element — supplemental conditioned air supplied from the home's HVAC — depending on the home's design and the crawl's volume.
Why 20-mil (and never 6-mil) for encapsulation
6-mil vapor barrier is the right product for a simple vapor-barrier-only install ($1,400–$3,600). For full encapsulation, 20-mil reinforced poly is the right product because:
- Tear resistance — service techs walk on it, future plumbers crawl over it, vermin sometimes try to chew through. 20-mil holds.
- Seam reliability — 20-mil seams taped with butyl-mastic last 20+ years. 6-mil seams degrade in 5–8.
- Heat resistance — Central Valley summers push crawl temps over 90°F. 6-mil softens, shrinks, and pulls at fasteners. 20-mil is dimensionally stable.
- Manufacturer warranty — every major liner brand (Carlisle, Stego, Tu-Tuf) warranties 20-mil for 15–25 years. 6-mil typically 5.
The sequence — what happens day-by-day
- Day 1: clear existing debris and old vapor barrier. Disinfect surfaces (IICRC-protocol if mold present). Install drainage rough.
- Day 2: install 20-mil liner on floor; mechanically fasten to walls; seal piers; tape seams. Cover vents with rigid foam.
- Day 3: dehumidifier install + condensate routing. Electrical circuit. Inspection.
- Days 4–5: punch + tune dehu setpoint to local conditions. Verify humidity drop. Final inspector visit.
The thing every encapsulation should come with — but doesn't always: a printed humidity reading before and after, dated, on the invoice. Without it you don't have proof the encapsulation actually did its job. Every network specialist includes this on the final invoice.
What you'll spend in 2026
- Standard 1,200 sq ft crawl, dry conditions, full encapsulation — $7,400–$8,800
- 1,500 sq ft crawl, moderate moisture, encapsulation + perimeter drain — $9,200–$11,400
- 1,800 sq ft crawl, wet conditions, full encapsulation + interior french + sump + dehu — $11,400–$13,800
- Pre-1980 home requiring joist sistering before liner — add $1,800–$3,400
- Mold remediation before encapsulation (if discovered) — add $2,400–$5,800
Permits & inspection
Encapsulation triggers a building permit in every jurisdiction in our service area (Davis, Sacramento, Roseville, Woodland, Vacaville, Folsom, etc.). The dehumidifier circuit triggers an electrical permit. Both are pulled by the network specialist before work starts. Inspections run rough mechanical (post-liner, pre-dehu) and final.
Common questions
Can encapsulation be done in a home with active mold?
Not directly — the mold has to be remediated first, then the encapsulation. Doing them in the wrong order traps active mold under the new liner. Network specialists handle both, sequentially, on a single project.
Does encapsulation lower my heating/cooling bill?
Modestly — typically 8–14% in our climate, with the dehumidifier counting against the savings. The bigger payback is structural: wood rot stops, fasteners stop corroding, and the home's first floor stays consistently warmer in winter.
How long does the liner last?
20-mil reinforced liner lasts 20+ years in our climate when installed correctly. The dehumidifier needs replacement every 8–12 years (about $1,200 in 2026 dollars).