Crawl Space Encapsulation & Repair in Chilliwack, BC

What Crawl Space Encapsulation Involves

Encapsulation seals your crawl space off from the ground and outside air, rather than just adding a layer of plastic over the dirt floor. We start by sealing foundation vents, since older Chilliwack homes built in the 1960s and 70s were designed with vented crawl spaces, a standard that's since been shown to pull humid outside air in rather than keep the space dry.

A heavy-duty vapour barrier, typically 12 to 20 mil reinforced polyethylene, covers the entire floor and runs up the foundation walls, overlapping and taped at every seam to form a continuous, sealed layer. Seams around piers, ductwork, and plumbing penetrations get sealed individually, since a single gap undoes a lot of the benefit. Rim joists and any exposed wood framing get insulated as part of the same job.

For crawl spaces with an active moisture or mould problem, we add a dehumidifier sized to the space, keeping relative humidity below the 55% threshold where mould growth stalls out. Some jobs also need drainage work underneath the barrier, a small perimeter channel and sump pump, if there's standing water or a high water table under the house rather than just damp soil.

Why Fraser Valley Crawl Spaces Are Especially Prone to Moisture

Chilliwack's crawl space problems come from a specific combination of factors that's worse here than in drier parts of the country. Heavy annual rainfall keeps the soil under and around the house saturated for long stretches of the year, and the clay-heavy Fraser Valley soil holds that water against the foundation rather than draining it away quickly.

Older vented crawl space designs make this worse, not better. The theory behind venting was that outside air would dry out the space; in practice, humid outside air condenses on the cooler surfaces inside the crawl space, adding moisture rather than removing it. Once relative humidity climbs past 60%, mould spores present in essentially every crawl space start actively growing, and wood framing exposed to that humidity for months at a time starts to lose structural integrity through rot.

This is a slow-moving problem. Moisture damage under a house progresses quietly for years before it shows up as a smell in the floors above or a soft spot in the subfloor, which is why most of the crawl spaces we inspect have more advanced damage than the homeowner expected going in.

Signs Your Crawl Space Needs Encapsulation

A musty smell in the rooms above the crawl space, especially one that's stronger in humid weather, is usually the first thing homeowners notice, even before they've been under the house to look. Visible mould or a white, fuzzy growth on floor joists and subfloor framing is a clear sign moisture levels have been elevated for a while. Standing water or consistently damp soil on the crawl space floor, sagging insulation that's fallen away from the subfloor, and rusted metal ductwork or fasteners are other common findings.

From inside the house, cold or uneven floors in the rooms directly above the crawl space, and a spike in main-floor humidity your dehumidifier can't keep up with, both point back to an unsealed crawl space feeding moisture into the house above it.

Cost and Timeline

Basic encapsulation, vapour barrier and sealing without insulation or a dehumidifier, typically runs $2,500 to $5,000 for an average 500 to 800 sq ft crawl space. Full encapsulation, including insulation, a dehumidifier, and drainage where needed, runs $7,000 to $15,000 or more. Most homes land somewhere in between depending on square footage and how much moisture or existing mould needs to be addressed first.

A dehumidifier adds roughly $1,500 to $3,000 installed; drainage work, if standing water is present, adds more depending on scope. Most encapsulation jobs take one to three days, longer if there's existing mould that needs remediation before the barrier goes in, since sealing a crawl space with an active mould problem underneath the new barrier only traps it in place.

We walk the crawl space during the free inspection and tell you plainly whether you need basic sealing or the full system, rather than defaulting to the most expensive package.