Crawl space encapsulation in Tacoma is a full-system moisture control installation: heavy-mil vapor barrier sealed to the foundation, perimeter interior drainage, dedicated dehumidifier, and sump pump where required. A plain vapor barrier alone doesn't solve the Pacific Northwest humidity problem. Full encapsulation converts a vented, humid, dirt-floor crawl space into a sealed, conditioned environment — the only way to protect structural repair work long-term.
$350 credits 100% toward your encapsulation project.
Encapsulation sold for a few thousand dollars is almost always vapor-barrier-only. That's the cheapest component of a real system and on its own it doesn't solve the Tacoma humidity problem. Full-system encapsulation includes four integrated components working together.
20-mil reinforced vapor barrier, sealed to the foundation walls, piers, and penetrations. Heat-welded seams, mechanical attachment at wall terminations, sealed at every penetration. Not a 6-mil poly sheet laid on the dirt.
Interior perimeter drain channel that captures any groundwater migration at the footing. Channel tied to sump pit (or gravity discharge where grade allows). Prevents the vapor barrier from pooling standing water.
Purpose-built commercial dehumidifier sized to crawl square footage. Automatic humidity control set point. Drain line routed to sump or approved discharge. Maintains interior humidity below 50% year-round — the threshold that stops fungal growth.
Sump pit and pump where groundwater intrusion or site drainage requires active removal. Discharge line routed away from the foundation per code. Backup battery pump option for critical installations.
Vented crawl spaces in the Pacific Northwest pull humid outside air through the foundation vents year-round. That humid air contacts the cool wood framing — joists, sill plates, subfloor — and condenses on those surfaces. A plain vapor barrier on the ground blocks soil moisture migration but does nothing to stop the condensation cycle caused by vented humid air. Over years, that condensation cycle is what causes the fungal activity that leads to dry rot, joist rot, subfloor failure, and sill plate damage.
License Note: Crawl space encapsulation is performed by APCON LLC under GC License #APCONL*825QO. Sump pump electrical tie-in is coordinated with licensed electrical contractors per RCW 19.28. Plumbing discharge lines requiring sanitary sewer connection are coordinated with licensed plumbing contractors per RCW 18.106.
Encapsulation is sequenced so each phase builds on the previous. Skipping phases produces a system that looks complete but doesn't function. Here's the sequence we follow on every Tacoma encapsulation project.
$350 forensic diagnostic maps crawl dimensions, moisture sources, existing framing condition, drainage pattern, and equipment placement. Produces a lump-sum fixed-price written bid.
Debris removal, old vapor barrier removal, rodent damage cleanup where present, grading correction if needed for drainage flow. Structural repair scope completes in this phase if bundled.
Install perimeter interior drain channel tied to sump pit (or gravity discharge where grade allows). Proper slope to ensure flow. Filter fabric on drain to prevent silt fouling.
Where required: sump pit excavation, pump installation, discharge line routed to code-compliant termination. Electrical tie-in coordinated with licensed electrical contractor per RCW 19.28.
20-mil reinforced vapor barrier installed across floor, sealed to foundation walls with mechanical termination and sealant. Piers wrapped and sealed. All penetrations (plumbing, electrical, vents) sealed airtight.
Install dehumidifier, drain line to sump, humidistat setup. Seal all foundation vents. Commission system and verify humidity drawdown. Provide homeowner documentation and service schedule.
Encapsulation rarely stands alone. In most Tacoma projects it runs concurrent with structural repair scope.
The $350 diagnostic maps moisture sources, measures square footage, plans system placement, and produces a lump-sum fixed-price bid. If you proceed, the fee credits 100% to the installation.
Book a $350 Crawl Diagnostic 📞 Call Direct