Crawl Space Waterproofing Cost in Portland

The short answer

Crawl space waterproofing in the Portland metro typically runs $3,825 to $6,800 in 2026. Hillside lots with long discharge runs, or crawl spaces that already flood, run $7,225 to $10,100.

But "waterproofing" is not one job. Before that range means anything, you need to know which of these you are being quoted:

If you are comparing two quotes with a wide gap between them, this table is usually the explanation. They are not the same job.

A quote that seals the whole crawl space, with the vents and access closed and a way to condition the air, is an encapsulation quote, whatever the paperwork calls it. That is a different job at a different price: see crawl space encapsulation cost.

Which scope does your crawl space need?

The deciding question is where the water comes from, not how wet the space is. Three broad cases:

• Water appears during and after rain, then recedes. Surface water is reaching the foundation. Start with the cheap fixes: downspout extensions and regrading the first several feet away from the house. These are often a few hundred dollars and sometimes solve it outright. If they do not, interior perimeter drainage is next.
• Water sits through the wet season regardless of individual storms. The winter water table has risen into the soil under the house. Grading will not fix this. You need drainage with somewhere for the water to go, which usually means a sump unless the lot slopes enough to daylight the line.
• The soil is damp and the air is humid but there is no standing water. This is a vapor problem, not a water problem, and drainage is the wrong purchase. Vapor control is roughly a third of the price.

A free crawl space inspection exists largely to answer this question — the right diagnosis is worth more than any single line item on the bid. If you want to work through the symptoms first, water in your crawl space after rain covers each source and how to tell them apart.

What moves the price in the Portland metro

• Where the water can be discharged. The largest local variable. A sloped lot that lets the line daylight downhill is the cheap case. A flat lot needing a sump, a long run to the property line, or a tie-in to a storm system pushes toward the top of the range and past it.
• Hillside conditions. The West Hills, Portland's east-side slopes and the Tualatin Mountains foothills produce crawl spaces taking water laterally from uphill. These need interceptor drains as well as perimeter drainage — the $7,225 to $10,100 cases.
• Linear feet of perimeter. Drainage is priced substantially by the run, so footprint shape matters as much as square footage. A long rectangular footprint costs more to ring than a compact square of the same area.
• Soil. A large share of the Portland metro's mapped soil carries a "somewhat poorly drained" to "very poorly drained" classification in USDA's soil survey. That is part of why water that gets under a house here tends to stay rather than soak away, and why perimeter drainage is a more common recommendation locally than in better-draining regions.
• Access and headroom. Gravel, pipe, and spoil all move through the crawl space hatch by hand. Older Portland homes with shallow clearances take longer for identical work.
• Whether the space has to be cleaned out first. Saturated insulation, debris, and standing water all mean removal and disposal before the work starts.

Why timing changes what you learn (and sometimes what you pay)

Portland's rain is heavily seasonal. At Portland International Airport, the 1991–2020 normals put annual precipitation at 36.92 inches, with November, December and January alone accounting for about 16.25 inches — roughly 44 percent of the year's total in three months. July and August together average just over an inch.

Two practical consequences. First, an inspection in August may find a crawl space that looks completely dry and still floods in December — so a summer inspection should be reading evidence (staining, high-water marks, efflorescence, rust lines) rather than current conditions. Second, the dry months are the easier window to do drainage work, because the excavation is not happening in saturated soil. Neither is a reason to wait if water is actively sitting under your house now.

What this price does not include

• Mold remediation. Water and mold travel together, but they are separate scopes. Drying the space does not remove growth that is already there.
• Insulation replacement. Batt insulation that has been wet is not salvageable and is usually replaced after the space is dry, not before.
• Structural repair. If sustained moisture has caused decay in joists or rim joists, that is its own line item and its own trade.
• Basement work. If the wet space is a basement rather than a crawl space, the scope and price are different — $7,225 to $15,300 — because finished space, interior walls and floor replacement come into play. See basement waterproofing.

Portland Crawlspace Pros connects homeowners with independent licensed contractors and does not perform construction work. Ranges here are Portland-metro market figures, not a quote — a free in-home inspection is what produces a firm number and, more usefully, a diagnosis.