Seattle Crawlspace Cost Index

The index

Typical range is the band this model puts on the reference project in the Seattle metro. The premium band is a different and larger scope, not a more expensive contractor — the conditions that trigger it are named in the same row. Expand any service for the full included and excluded line items.

Reference project for every row: 1,200 to 1,500 square feet of crawl space floor, damp but without standing water at the time of the quote, a standard exterior or interior hatch with roughly 3 feet of working clearance, on a single-family home on a continuous perimeter foundation, in the Seattle metro (King County and south Snohomish County), priced in 2026 dollars before sales tax.

Derivation of every row: Portland-metro editorial model x 1.05418 (BEA 2024 all-items Regional Price Parities, Seattle-Tacoma-Bellevue 111.133 / Portland-Vancouver-Hillsboro 105.421), rounded to the nearest $25, before Washington retail sales tax. No contractor quotes were collected for the Seattle market.

Scope, assumptions and limitations by service

This is the half of the dataset that a price column cannot carry, and the half that explains why two quotes for the same word can differ by thousands. Read it as a checklist against a written scope of work.

Excluded from every range in this dataset

• Washington retail sales tax, which applies to the full contract price, labor and materials together, at the rate for the job site: 10.55% in Seattle from October 1 to December 31, 2026. Every range here is before tax
• Permit fees, which vary by jurisdiction and are usually billed at cost
• Structural repair of framing found to be rotten once the space is opened up
• Asbestos or lead abatement, which is separate work no range here prices
• Electrical service upgrades where an existing panel cannot carry new equipment
• Landscape or hardscape restoration after exterior excavation

Sales tax on top of these ranges, by city

No range in this dataset includes Washington retail sales tax. The tax is added to the full contract price, labor and materials together, at the combined state and local rate for the place where the work is done. These are the Department of Revenue’s rates for October 1 to December 31, 2026, read on November 10, 2026. Unlike the price ranges, they are measured figures: read from the department’s table without alteration. The department republishes them every quarter, and its address lookup decides the rate for a specific house.

The state rate is 6.5% on every row; the rest is local. “Non-RTA” is the department’s label for the part of a city where the Regional Transit Authority tax does not apply. Two cities here extend into a second county and are listed once for each.

What moves a project inside these ranges

Every row above publishes a band rather than a figure. The width of that band stands for four properties of the specific house. Anyone applying one of these ranges to a real address needs to know which end of the band that address sits at, because for most services the two ends differ by a third or more — quoting the midpoint of a band to a low, wet crawl space is not a conservative estimate, it is the wrong number.

None of the four is a measurement of Seattle-area houses. This site has not surveyed how local crawl spaces split on any of them and makes no claim about it here. They are the properties the model’s bands are meant to span, and the same ones the homeowner-facing cost guide describes in narrative form.

What was originally built

This decides whether a job is a retrofit or a replacement. A crawl space with a bare dirt floor, low clearance and no functioning ground cover puts the whole scope in play and lands at the upper end. One with a degraded thin barrier and failed batt insulation over an otherwise sound space is a defined replacement scope, nearer the middle of the band.

Access and working clearance

A pure labor multiplier, and the one most often missing from a quote a homeowner is comparing. The reference project assumes roughly three feet of clearance and a standard hatch. Below about eighteen inches the same material takes materially longer to place, spoil and debris have to be moved by hand, and some equipment stops fitting. Two identical square footages with different clearance are not the same job and should not be read off the same point in the range.

Moisture severity, and whether it is still active

This drives sequence as much as price. Standing water or active mold adds remediation before the priced work can begin, and it usually means the moisture source has to be fixed first, which is a separate row in this table rather than a surcharge on this one. A range for encapsulation assumes a damp space, not a wet one; a wet space is normally two rows of this index, in order, not the top of one.

Hillside position and drainage complexity

The driver that pushes projects past the top of the typical band and into the premium column. On a lot that intercepts water moving downhill, the fix is exterior interception as well as interior management. The model prices a curtain drain at $2,250–$5,375 on top of the interior work, and roof and surface water rerouting at a further $700–$2,250. Long discharge runs to an approved point compound both. This is the difference between the typical and premium columns on the drainage and waterproofing rows.

Placing a specific property in these bands. The crawl space cost calculator is built from the same base ranges published here, and a build-time check holds it to reproducing the row above whenever it is asked about the reference project this table prices. Its own six inputs are not the four drivers listed above, though: it asks about service, floor area, moisture, access, insulation condition and timeline, so it will return figures outside a row's typical band by design as those inputs move away from the reference project. It returns a narrowed range, not a quote: only a contractor who has been under the house can produce one of those.

What the data basis labels mean

Every value this site publishes carries one of four classifications. They are not interchangeable, and the difference between the first and the third is the difference between a measurement and a judgement. Check the label before you reuse a number.

MEASURED Measured

A value reported directly by the authority that holds it, or read out of a legitimate published dataset without alteration. A code requirement quoted from the adopted code, a sales tax rate read off the state’s rate table, a rainfall total from the National Weather Service.

In this dataset: No row of the cost index is measured, and no published price on this site is. Measured values do appear around the prices: the Washington sales tax rates this site quotes are read from the Department of Revenue’s rate table, the two regional price parities and the two wage figures behind the adjustment are read from the Bureau of Economic Analysis and the Bureau of Labor Statistics, and code requirements are quoted from the adopted code. The climate and housing dataset states the basis of each of its own columns.

DERIVED Derived

A value calculated from measured inputs by a stated formula, where both the inputs and the formula are published so the result can be recomputed independently.

In this dataset: No row of the cost index is derived. The adjustment factor is derived: 1.05418 is one published price parity divided by another (111.133 / 105.421), and anyone can recompute it. But the thing it multiplies is an editorial estimate, and a calculation performed on an estimate returns an estimate. The same holds for the cost calculator, which adjusts a modeled base range and so returns a modeled range.

MODELED Modeled

An editorial estimate: a considered judgement about what a defined scope of work costs in a market, published with its assumptions and its derivation. It is not a measurement of that market, and adjusting it by a published index does not make it one.

In this dataset: Every row of the cost index. Each range is this publisher’s Portland-metro editorial model multiplied by 1.05418 and rounded to the nearest $25, before sales tax. This is the honest label for what this dataset is, and it is the reason the ranges are published as bands rather than as point estimates.

OBSERVED_QUOTE_DATA Observed quote data

A range computed from a sample of real quotes issued to real homeowners, published with its sample size, its median, and the dates the quotes were issued. Reserved for future use under a stated threshold of 30 quoted projects per service.

In this dataset: Nothing. This site does not hold a database of Seattle-area contractor quotes and does not present one. The classification is defined here so that the day such data exists it lands in a slot whose meaning was fixed before anyone had an interest in stretching it.

Download

Both files are generated at build time from the same file the website reads, so a download cannot fall out of step with the page. Each carries the dataset title, version, methodology URL, geography and reuse terms inside the file itself, so it still says what it is once it has been separated from this page.

Field dictionary

The same field names are used in both formats. This table is the source the downloads are built from, so a column cannot exist in a file and be missing here.

How to cite this

Use this form, or any form that carries the publisher, the dataset name and the review date:

Seattle Crawlspace Pros. "Seattle Crawlspace Cost Index." Updated November 2026. SeattleCrawlspacePros.com.

Please state the review date alongside any figure you quote, because the ranges are revised — a 2026 figure republished in 2028 with no date attached becomes a claim this site did not make. Linking to this page or to the methodology lets your reader check the basis for themselves.

What not to say. These are not average quotes, not a survey of contractors, not a market study, and not peer reviewed. They are one publisher's modeled estimates for a stated reference project, and none of the jobs described above has been priced from a collected quote. Seattle Crawlspace Pros also offers crawl space inspections, which is a reason to read these figures critically, and worth stating here rather than leaving to be discovered.

Maintenance and corrections

• Last reviewed: November 10, 2026, the day these ranges were derived. This moves only when someone actually re-examines the ranges — never because the site was rebuilt or an unrelated page was edited.
• Next scheduled review: February 1, 2027.
• Update cadence: the ranges are reviewed on the date above, which is when the Portland-metro model they are scaled from is next due for review; a change to that model, or a new year of Regional Price Parities, changes every figure here. The sales tax rates are a separate matter: they are the Department of Revenue’s for October 1 to December 31, 2026 and are printed with that period because the department republishes them every quarter. An out-of-cycle revision happens only when something makes a published figure wrong before the next review, and it is logged below with everything else. If the review date above is more than about a year old, treat the figures as stale and say so wherever you cite them.
• Methodology: How these figures are produced, including the reference project, the step-by-step method, the definitions and the limitations.
• Found an error? If a figure here does not match what you are seeing in the Seattle market, or a scope line is wrong, tell us. Say which service and what you are seeing. Corrections that change a number are recorded in the revision log below with the date they were made.

Recent revisions

If you cited a figure from this dataset, this is where you check whether it has moved since. The most recent changes are below, starting with how the first Seattle table was derived; the full revision history is kept on the methodology page.

1. November 10, 2026

   First Seattle table. Every range, premium band and add-on is this publisher’s Portland-metro editorial model multiplied by 1.05418, the ratio of the Bureau of Economic Analysis all-items Regional Price Parities for 2024 (Seattle-Tacoma-Bellevue 111.133 / Portland-Vancouver-Hillsboro 105.421), rounded to the nearest $25. All figures are before Washington retail sales tax. No contractor quotes were collected for the Seattle market, so every row is a modeled estimate. The index is a cost-of-living measure, not a construction cost index: using the ratio of construction and extraction wages in the same two metropolitan areas instead (1.068, Bureau of Labor Statistics, May 2025) would raise every figure by about 1.3% before rounding, and by no more than $525 on any row.