Crawl Space Repair in Hillsboro, OR

The basin Hillsboro sits in is filled with the Hillsboro Formation: close to 300 metres of fine-grained fluvial sediment washed in by streams draining the Coast Range. The name is not a coincidence, and neither is what it does to crawl spaces. Fine-grained basin fill holds water.

The soil survey bears it out. USDA Natural Resources Conservation Service data clipped to the Hillsboro place boundary rates 61.6% of the mapped area as somewhat poorly, poorly or very poorly drained — the highest of any incorporated city on the westside, and second highest anywhere on this site. Just 2.2% is unrated, so the reading covers effectively the whole city.

Three fifths of Hillsboro is on ground that holds water through the wet season. That is a different starting position from most of the metro, and it changes what a reasonable first quote looks like. Where the honest general advice is to establish the water source before pricing drainage, Hillsboro is one of the few places where drainage is the likely answer often enough that a bid leading with it is starting from the base rate rather than reaching.

It also means that sealing without water management is a more expensive mistake here than elsewhere. A crawl space that takes liquid water and then gets encapsulated has had the water sealed in with it.

The Census American Community Survey five-year estimates for 2019 to 2023 give Hillsboro a median year built of 1997 with a margin of error of one year, and 24.7% of homes built before 1980. That reads as a Silicon Forest new-build town, which is most of the story and not all of it: 4.5% of the stock predates 1950.

Those two populations need different work. The central Hillsboro pre-1950 houses tend toward small crawl spaces with low clearance, no ground cover from the original build, and often no functioning perimeter drain at all — on ground that, per the figure above, is holding water for months. That is the combination that produces the largest bids in this city.

The Orenco, Tanasbourne, Witch Hazel and Bethany stock is the opposite problem: sound construction now hitting twenty to thirty years, where the original perimeter drainage exists but has silted or settled, downspout extensions are undersized, and the original barrier has torn. Cheaper scope, different diagnosis.

Establish which population your house belongs to before reading any quote. In a city with this much new construction it is easy for a contractor to assume the newer pattern and price the wrong job.

One methodological note that happens to favour Hillsboro. This site does not publish a rainfall figure for any city, because precipitation is measured at instruments and instruments do not respect city limits. Hillsboro is the closest case to an exception: the nearest NOAA station with published 1991–2020 normals is 1.1 miles away, closer than for any other city covered here.

The caveat still holds, though. Only three qualifying stations sit within fifteen miles of Hillsboro, and they differ from one another by 8.14 inches of annual normal precipitation. A single number attributed to the city would still be a station's number wearing a city's name, so this site gives you the station and the distance instead and lets you judge.

Hillsboro issues building, plumbing, mechanical and electrical permits through its own permitting centre. The electrical category explicitly covers alteration or extension of branch circuits, which is the description a sump pump circuit falls under — so on a drainage job here, the permit for the pump and the permit for the work come from the same counter.

That is not universal even within this county. Washington County's building service covers unincorporated areas only, and Sherwood routes its electrical permitting to the county while keeping the rest. Given how often the right answer in Hillsboro involves water management, and how often water management involves a pump, it is worth confirming a contractor knows which arrangement applies here.

The flood record is the county's rather than the city's. The FEMA Flood Insurance Study for Washington County records February 1996 as the largest flow ever measured on the Tualatin River, at an 84-year return interval, ahead of December 1933 at 23,300 cubic feet per second and January 1974 at an estimated 22,300. Rock Creek, which runs through the north of the city, is among the detailed study's flooding sources. As everywhere, whether a specific address is inside a mapped zone is a FIRM panel question and not one an estimate should answer.