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The short answer
Crawl space waterproofing in the Seattle metro typically runs $4,025 to $7,175 in 2026. Hillside lots with long discharge runs, or crawl spaces that already flood, run $7,625 to $10,650. Both are before Washington retail sales tax, which applies to the full contract price: 10.55% in Seattle from October 1 to December 31, 2026.
But "waterproofing" is not one job. Before that range means anything, you need to know which of these you are being quoted:
| Scope | What it does | Modeled range |
|---|---|---|
| Vapor control only | Blocks soil moisture evaporating upward. Does nothing about liquid water. | $3,400–$4,675 |
| Sump pump only | Removes water that already collects, where drain lines exist but the pump does not. | $1,600–$3,125 |
| Interior perimeter drainage | Collects water at the footing and routes it out. A common answer for a crawl space that is wet all winter. | $4,025–$7,175 |
| Full waterproofing system | Drainage plus wall treatment, grading correction, and vapor control together. | $4,025–$7,175 |
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 the air ventilated or conditioned, 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. Groundwater has risen into the soil under the house, or is perched on the hardpan beneath it. 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 for a gravity line and there is a permitted place for it to end.
- 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 on its own is the $3,400 to $4,675 line in the table above.
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 drives a drainage quote
- Where the water can be discharged. The largest local variable. A sloped lot where a line can run downhill to a permitted outlet is the cheap case. A flat lot needing a sump, a long run to an approved discharge point, or a connection to the public system pushes toward the top of the range and past it. Inside the City of Seattle, that connection takes a side sewer permit, and the discharge rules are set out in the price factors below.
- Hillside conditions. On a sloped lot, water can reach a crawl space sideways from uphill, which needs an interceptor drain as well as perimeter drainage — the $7,625 to $10,650 cases. Slopes also limit where the water may go: the City of Seattle’s stormwater manual says roof water is not typically dispersed onto the ground in landslide-prone areas or within a steep-slope setback of ten times the slope’s height, which can lengthen the discharge run.
- 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, and what is under it. Among the cities this site covers where USDA’s soil survey rates most of the ground, the highest shares in the somewhat poorly to very poorly drained classes are Auburn (23.4%), Issaquah (19.7%), and Kent (19.2%). The survey does not rate most of Burien, Shoreline and Seattle, so their shares say nothing either way. Below the soil, the City of Seattle’s landslide study describes the glacial till known locally as hardpan as very dense and relatively impervious, with water perching on top of it through the winter. That is part of why water that gets under a house here tends to stay rather than soak away.
Sales tax, crawl space height and access, standing water, debris, permits and rebates are set out with the Washington and City of Seattle rules behind them in what moves the price in Seattle, below.
Why timing changes what you learn (and sometimes what you pay)
Seattle’s rain is heavily seasonal. At Seattle-Tacoma International Airport, the 1991–2020 normals put annual precipitation at 39.34 inches, with October through March accounting for 29.65 inches — 75.4% of the year’s total in six months. The other six months together average 9.69 inches.
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
- Washington sales tax. It applies to the whole contract price, labor and materials together, at the rate for the address: 10.55% in Seattle.
- 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 — $7,625 to $16,125 — because finished space, interior walls and floor replacement come into play. See basement waterproofing.
Ranges here are modeled Seattle-metro figures, not a quote — a free in-home inspection is what produces a firm number and, more usefully, a diagnosis.
What moves the price in Seattle
The local conditions that move a quote, each with the Washington or City of Seattle rule or program behind it. Dollar figures are this site’s modeled adjustments before sales tax, the same ones the calculator applies; the documents are listed under Sources. Where a rule is the City of Seattle’s, it says so: other cities set their own.
Sales tax
Every range on this site is before Washington sales tax. A retail sale in Washington includes the labor and services in repairing or improving an existing building (RCW 82.04.050), and the Department of Revenue has the contractor collect the tax on the whole contract price, state it separately from the price, and charge the rate for the place where the work is done. The combined rate in Seattle is 10.55% from October 1 to December 31, 2026, and across the cities this site covers it runs from 9.9% to 10.7%. The department republishes the rates each quarter, and its address lookup decides the rate for a specific house. Before comparing a bid with anything on this page, check whether its total is before or after tax.
Crawl space height and access
Every range on this site assumes a standard exterior or interior hatch with roughly 3 feet of working clearance. The residential code sets only the minimum way in: an access opening through the floor must be at least 18 by 24 inches, and one through a perimeter wall at least 16 by 24 inches (R408.4, a section Washington adopts without amendment). Everything goes in and out through that opening by hand, pipe, drain rock and trench spoil included, so a space that meets the minimum can still be slow to work in. In this site’s model, low clearance adds about $450 in labor time and clearance under 18 inches about $900.
Standing water, and where it can go
Standing water is what this work is for, so the price question is less whether water is present than where it can be sent. The residential code expects a drained crawl space: where groundwater can rise to within 6 inches of the finished floor at the perimeter, or surface water does not readily drain from the site, the grade under the house has to be as high as the finished grade outside unless an approved drainage system is provided (R408.6).
Inside the City of Seattle, where collected water may go is regulated. The city’s Stormwater Code prohibits sending anything but stormwater to a drainage system, then lists uncontaminated water from crawl space pumps, uncontaminated pumped groundwater and approved footing and foundation drains among the discharges it permits (SMC 22.802.020 and 22.802.030); drainage water may go to a sanitary sewer only with the approval of the Director of Seattle Public Utilities. Connecting a drain to the public system takes a side sewer permit from Seattle Public Utilities, which also says footing drains cannot be daylighted to the right of way. These are City of Seattle rules. Other cities have their own, which this site has not read, so outside Seattle the question goes to that city’s drainage or public works desk. Long discharge runs are one of the conditions this site prices into the premium waterproofing band, $7,625 to $10,650.
What the code requires on the ground
A ground cover goes down over the finished drainage work, because Washington’s residential code requires a ground cover of 6-mil black polyethylene or an approved equal, lapped 6 inches at the joints and run to the foundation wall (WAC 51-51-0408, R408.1). The only exception is a crawl space with a concrete slab floor at least 2 inches thick. Whether a drain and sump bid includes putting the cover back, or replacing it, is worth reading for.
Debris and what has to come out first
The residential code requires the grade under the house to be cleaned of all vegetation and organic material (R408.5, adopted without amendment), and nothing new goes down over what is already there. Wet or rodent-damaged insulation that has to come out adds about $2,500 in this site’s model. Droppings and nesting material are wetted and disinfected, not swept or vacuumed dry, and contaminated insulation is bagged, as the CDC sets out, so it takes longer than clearing ordinary debris. Rot found once the space is opened up adds $375 to $1,350 per repair location, and cannot be priced before it is seen.
Permits
No range on this site includes permit fees, which vary by jurisdiction and are usually billed at cost. Inside the City of Seattle the residential code requires a building permit to alter or repair a house, then exempts minor repairs valued at $6,000 or less in any six-month period that do not touch loadbearing support or reduce ventilation, and listed minor work that includes insulating an existing building and like-for-like replacement of deteriorated members (Seattle Residential Code R105.2). The code section does not say how the city treats a ground cover, a sealed crawl space or a sump basin; that is a question for the Seattle Department of Construction and Inspections. New wiring for the pump is the plainest permit item: an electrical permit is needed whenever wiring is installed, altered or extended, which covers a new circuit or receptacle. Plumbing permits in Seattle and unincorporated King County come from Public Health – Seattle & King County, and connecting a drain to the public system takes a side sewer permit from Seattle Public Utilities.
Outside Seattle, the building department of the city or county the house is in sets the rule. Each amends the permit section of the state code itself, and this site has not read their exemptions, so ask that permit desk before relying on a bid that says no permit is needed.
Rebates
Nothing in a drain and sump scope is an insulation measure, so none of this range earns a utility rebate. Where wet floor insulation comes out during the job, its replacement can. Which program applies depends on what heats the house. Puget Sound Energy pays $2.50 per square foot, up to $5,000, toward floor insulation where PSE electricity or PSE natural gas is the home’s primary heat: a site-built home built 1989 or before, with 4 inches or less of existing insulation, finished to R-30 or a full joist cavity, with the work done by a PSE-approved contractor who takes the rebate off the invoice. Snohomish County PUD pays $1.00 per square foot in electrically heated homes it serves, for floor insulation going from R-11 or less to R-30, through a PUD registered contractor. Seattle City Light lists no standard insulation rebate; its insulation help runs through HomeWise, the city’s free weatherization program for income-qualified households. The state HEAR program pays toward electric equipment, not insulation. PSE states that its rebates can change or end without notice; the rebate guide has the conditions in full. The federal Energy Efficient Home Improvement Credit covered improvements made through December 31, 2025, so work done in 2026 does not qualify for it.
Sources
The rainfall normals and soil drainage shares come from this site's climate and housing dataset, which cites NOAA and USDA; the hardpan description is from the City of Seattle's landslide study and the dispersal limits from its stormwater manual. The price-factor section draws on Washington's sales tax law, R408.1 and R408.4 to R408.6 of the residential code, the City of Seattle's stormwater, side sewer, building, electrical and plumbing permit rules, the CDC's rodent clean-up guidance, the PSE, Snohomish County PUD and Seattle City Light programs, and the IRS page on the expired federal credit.
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NOAA National Centers for Environmental Information, U.S. Climate Normals (1991–2020) — Annual/Seasonal and Monthly (normals-annualseasonal-1991-2020, normals-monthly-1991-2020) Open dataset Checked
Every precipitation figure in the Seattle-metro climate and housing dataset: annual and monthly precipitation normals, the October–March total summed from the monthly normals, the average number of days per year at or above 0.10, 0.50 and 1.00 inches, and the completeness flag and years of record NCEI publishes alongside each value, for the eight stations within 15 miles of a served city with at least 20 years of record (Snoqualmie Falls, Landsburg, Monroe, Tacoma #1, Seattle-Tacoma International Airport, Seattle Sand Point, Renton Municipal Airport and Everett Snohomish County Airport). Pulled through the NCEI data access service on 2026-11-10.
Note: A normal is a 30-year statistic for one instrument at one point, not a value for the surrounding city. NCEI publishes a completeness flag with every value and this site republishes it, because a station with 20 years of record and one with 29 are not equally strong evidence. Seattle Boeing Field has 19 years behind its annual normal and is not published.
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USDA Natural Resources Conservation Service, Soil Survey Geographic Database (SSURGO), via Soil Data Access (muaggatt.drclassdcd — drainage class, dominant condition) Open dataset Checked
The soil drainage columns for the 19 cities in the Seattle-metro climate and housing dataset: the share of each city’s mapped area whose dominant soil drainage class is somewhat poorly drained, poorly drained or very poorly drained, and the share carrying no drainage class at all. Computed on 2026-11-10 by intersecting each Census place boundary with the SSURGO map units of the King County Area, Snohomish County Area, Pierce County Area, City of Seattle, City of Tacoma and Mount Baker-Snoqualmie National Forest survey areas and area-weighting the result; the survey-area versions were read on 2026-11-11.
Note: SSURGO assigns no drainage class to Urban land map units or to water. In Seattle, Shoreline and Burien more than four fifths of the mapped area is unrated Urban land, so their wetter-class shares are near zero because the ground is unrated, not because it drains well, and they are not compared with the other cities. Drainage class also describes natural soil in place — not the fill, the grading or the downspout run at any individual house.
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Seattle Public Utilities (prepared by Shannon & Wilson), Seattle Landslide Study, Volume 1 Checked
That Vashon till, known locally as “hardpan”, is very dense and relatively impervious, so water soaking down through the deposits above it normally perches on top of it; that the contact between recessional outwash and till is normally less than 10 feet deep and the water perched there normally dries up in spring or summer and returns in winter; that the boundary where groundwater perches on the Lawton Clay is commonly termed “The Contact”; and that the study’s database holds 1,326 landslides reported through June 1999, records going back to 1890, about 84 percent with some human influence, landsliding in only about 1 percent of the city, and the highest densities in Southwest Magnolia, Southwest Queen Anne, Madrona, Interlaken and Alki.
Note: The PDF prints no date; 2000 is the year Seattle Public Utilities gives for it. A 2003 update added about 110 landslides; this site quotes the original figures.
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Seattle Department of Construction and Inspections and Seattle Public Utilities, Seattle Stormwater Manual, Volume 3, Project Stormwater Control (2026 edition, Directors’ Rule 03-2026 / DWW-200, effective July 1, 2026; sections 5.3.1.2 and 5.3.3.5) Checked
That a downspout splashblock or rock pad must be at least 5 feet from a structure, with a 10-foot setback recommended from a building with a basement, and serve no more than 700 square feet of roof (5.3.3.5); and that dispersing roof water is not typically permitted in landslide-prone areas or within a steep-slope setback of ten times the slope’s height (5.3.1.2).
Note: City of Seattle rules. Other cities in the area use their own stormwater manuals.
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Washington State Legislature, RCW 82.04.050 — “Sale at retail,” “retail sale” (Subsection (2)(b)) Checked
That a retail sale in Washington includes the charge for labor and services in constructing, repairing, decorating or improving new or existing buildings for consumers, including installing or attaching tangible personal property. This is why sales tax applies to the price of crawl space work on a home, labor included.
Note: The section was amended twice in 2026 and the Legislature’s page prints more than one version of it. Subsection (2)(b) reads the same in each version on the page.
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Washington Department of Revenue, Construction industry guide: Custom construction Explanatory summary, not the governing text Checked
How the department applies the tax to construction for a landowner: the prime contractor collects retail sales tax on the gross contract price without deducting costs, the invoice must state the tax separately (a quoted price is presumed not to include it), and retail construction services are taxed at the combined rate for the location where the construction takes place.
Note: The department’s guidance for contractors, not the statute. It cites RCW 82.08.050 for the separate-statement rule; this site has not read that section itself.
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Washington Department of Revenue, Local sales and use tax rate table (Quarter 4 2026, effective October 1 through December 31, 2026) Checked
The combined state and local retail sales tax rate for each city this site covers, by Department of Revenue location code: from 9.9% in Everett to 10.7% in Lynnwood and Edmonds, and 10.55% in Seattle. The state rate is 6.5% on every row.
Note: These rates apply from October 1 to December 31, 2026; the department republishes the table every quarter. Several cities have more than one location code, with a lower rate where the Regional Transit Authority tax does not apply or a different rate in a second county. The department’s address lookup (dor.wa.gov/TaxRateLookup) decides the rate for a specific house.
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Seattle Department of Construction and Inspections, 2021 Seattle Residential Code, Chapter 4, Foundations (Section R408, pages 4-47 and 4-48) Checked
Two things. First, that Seattle’s R408.1, R408.2 and R408.3 carry the Washington-amendment marker and read the same as WAC 51-51-0408, apart from “Appendix F” where the state rule says “Appendix AF”; the copy shows the model code’s wording struck through, including its menu of alternatives for an unvented crawl space (dehumidification, conditioned supply air, perimeter-wall insulation), which is how the two numbered conditions of R408.3 are read as applying together. Second, the sections Washington does not amend, R408.4 to R408.6: an access opening not smaller than 18 by 24 inches through the floor or 16 by 24 inches through a perimeter wall; the under-floor grade cleared of vegetation and organic material, and forms and construction materials removed; and the under-floor grade as high as the outside finished grade where groundwater can rise to within 6 inches of the finished floor at the perimeter or surface water does not drain readily, unless an approved drainage system is provided.
Note: The PDF marks additions by underline, which is lost when its text is extracted. “No Seattle-only change to R408” is drawn from the match with the state rule, not from a statement by the city. R408.4 to R408.6 are model code text and are summarised here, not reproduced.
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Washington State Legislature, WAC 51-51-0408 — Section R408, Under-floor space (Washington State Residential Code, amended by WSR 23-23-104) Checked
What Washington requires under a house: ventilation at 1 square foot per 300 square feet of under-floor area; 6-mil black polyethylene ground cover with joints lapped 6 inches, extending to the foundation wall, which may be omitted where the crawl space has a concrete slab floor at least 2 inches thick; vent coverings with a least dimension of no more than 1/4 inch (corrosion-resistant wire mesh at 1/8 inch), and operational louvers permitted; ventilation reducible to 1/1,500 where a Class I vapor retarder covers the earth, with a radon vent built to Appendix AF required where ventilation is below 1/300 or operable louvers are installed. Vents may be omitted only where both numbered conditions of R408.3 are met: a continuous Class I vapor retarder lapped and sealed 6 inches, extending 6 inches up and sealed to the stem wall, with an Appendix AF radon system; and continuously operated mechanical exhaust at 1 cfm per 50 square feet. R408.8 is not adopted in Washington.
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City of Seattle, Stormwater Code, Seattle Municipal Code Title 22, Subtitle VIII (July 2026 compilation; SMC 22.802.020 and 22.802.030) Checked
Where pumped crawl space water may go inside Seattle: SMC 22.802.020.B prohibits any discharge to a public or private drainage system that is not entirely stormwater, except as SMC 22.802.030 allows; SMC 22.802.030.B lists as permissible, unless the Director of Seattle Public Utilities finds a water quality problem, uncontaminated pumped groundwater, uncontaminated water from crawl space pumps, approved footing drains and other subsurface drains, and foundation drains; and SMC 22.802.030.C lets the Director approve drainage water to a sanitary sewer only case by case.
Note: The city’s own compilation, which it labels unofficial; the Seattle Municipal Code is the official text. These are City of Seattle rules. Every other city in the area has its own stormwater code, which this site has not read.
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Seattle Public Utilities, Side Sewer Permits Checked
That in Seattle a side sewer permit is required to connect a property to the public sewer or a storm drain and to repair, alter or add to a sanitary or drainage side sewer; that the whole side sewer to the public main is owned and maintained by the property owner; that for foundation drains only the solid pipe from the perforated footing drain to the drainage system counts as side sewer; that footing drains cannot be daylighted to the right of way; that piping inside the building is plumbing, permitted by Public Health; and that work in the right of way also needs a Seattle Department of Transportation permit.
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U.S. Centers for Disease Control and Prevention, How to Clean Up After Rodents (Healthy Pets, Healthy People — Rodent Control) Checked
The rule against sweeping or vacuuming dry droppings, urine and nesting material; the 30-minute ventilation step; the bleach dilution (1.5 cups per gallon, or 1 part in 9) and 5-minute dwell time; the instruction to bag contaminated insulation and stay upwind while removing it; and the personal protective equipment specified for heavy infestations, including a HEPA-filtered half-mask respirator.
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Seattle Department of Construction and Inspections, 2021 Seattle Residential Code, Chapter 1, Administration (Sections R105.1 and R105.2) Checked
When a building permit is needed in the City of Seattle. R105.1: a permit is required to construct, alter or repair a building, and all work must meet the code whether or not a permit is required. R105.2 item 1: no permit for minor repairs or alterations valued at $6,000 or less in any six-month period, provided no loadbearing support is removed, reduced, altered or relocated and ventilation is not reduced. R105.2 item 2: no permit, provided the building envelope is not changed, for listed work that includes insulating existing buildings and in-kind or similar replacement or repair of deteriorated members.
Note: City of Seattle only, and it is the building permit only: electrical, plumbing and side sewer permits are separate. The chapter does not say how the department classifies a ground cover, a sealed crawl space or a sump basin.
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Seattle Department of Construction and Inspections, Electrical Permit Checked
That in Seattle an electrical permit is needed whenever wiring is installed, altered, extended or connected to equipment, which covers a new receptacle or circuit for a sump pump or dehumidifier; that a professional applying needs a Washington electrical contractor’s license and a Seattle business license; and that owners may do their own electrical work on a property they own and occupy.
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Public Health — Seattle & King County, Plumbing and gas piping: applications and permits Checked
That plumbing permits in Seattle and unincorporated King County are issued by Public Health — Seattle & King County, not by the city’s building department; that a permit is required to install, relocate or change a plumbing system; and that a property in another King County city gets its plumbing permit from that city.
Note: The page does not say whether adding or replacing a sump pump needs a plumbing permit. The program’s permit-applicability document, which reportedly does, could not be opened, so this site does not state it.
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Puget Sound Energy, Weatherization rebates Checked
The PSE amounts and conditions this site quotes: floor insulation at $2.50 per square foot up to $5,000, in a site-built home built 1989 or before with 0 to 4 inches of existing insulation, finished to R-30 or a full joist cavity, where existing insulation may not be removed to qualify and the thermal boundary may not be moved; floor air sealing at $0.20 per square foot up to $400; duct sealing and insulation up to $1,000 per home, duct sealing only up to $550; that the customer must use PSE electricity or PSE natural gas as the primary source of space heating and live in a single-family home of four units or fewer or a manufactured home; that the work must be done by a PSE Recommended Energy Professional or Trade Ally, who takes the rebate off the invoice; that self-installed work does not qualify; and that the rebate cannot exceed the price of the work.
Note: PSE states that this is a tariffed service that can change or end without notice, and the page gives no program year. The page lists no rebate for a ground cover, vapor barrier, dehumidifier or drainage. It still says a federal tax credit may be available; the IRS says that credit ended for work after December 31, 2025.
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Snohomish County Public Utility District No. 1, Weatherization Rebates Checked
The Snohomish PUD amounts and conditions this site quotes: insulation at $1 per square foot for customers with electrically heated homes, where floor insulation must go from R-11 or less to R-30; duct sealing in a single-family home at $5 per linear foot up to $450; that the customer must own a single-family or manufactured home, or a townhouse or condominium in a building of up to four attached dwellings; and that the work must be done by a PUD registered contractor, who includes the rebate in the bill.
Note: The page states no cap on the insulation rebate and no end date. It lists no rebate for a ground cover, vapor barrier or air sealing.
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Seattle City Light, Home Energy Solutions Checked
That Seattle City Light’s residential page lists no standard rebate for insulation, air sealing or duct sealing: it advises sealing and insulating floors over crawl spaces, and sends insulation help to the income-qualified HomeWise program.
Note: An absence read from one page on one day. City Light’s offers change; check the page before relying on this.
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City of Seattle, Office of Housing, Weatherization (HomeWise) Checked
That HomeWise provides free weatherization, including insulation and duct and air sealing, to income-qualified households: homeowners or renters inside Seattle city limits, and Seattle City Light customers outside the city whose homes are electrically heated; that eligibility depends on income, heat source and whether the home is rented or owned; and that the program selects and manages the contractor.
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Washington State Department of Commerce, State Home Electrification and Appliance Rebates (HEAR) Program Checked
That the state HEAR program’s eligible items are electric equipment (heat pumps, heat pump water heaters, induction cooking, heat pump dryers, and the panel and wiring upgrades they need), and that insulation, air sealing and vapor barriers are not on the list.
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Internal Revenue Service, Energy Efficient Home Improvement Credit Checked
That the credit can be claimed for improvements made through December 31, 2025, so crawl space work done in 2026 does not qualify for it; that it equalled 30% of qualified expenses, with insulation and air sealing materials or systems meeting IECC standards among the qualifying building envelope components; and that it applied to improvements to an existing main home, not to a landlord who does not live in the home.
Note: The IRS summary page, not the statute or the form instructions. It is cited only for the credit’s end date and scope; it says nothing about deductions, rental property or a home sale, which this site does not cover.
Sources last checked between and ; the date beside each one is when it was last opened. Where a figure comes from a document that is revised on a schedule, the edition or version is named above so you can confirm it against the current one yourself.
Estimate Your Waterproofing Cost
Modeled 2026 estimates for the Seattle metro, before Washington sales tax (10.55% in Seattle), not collected contractor quotes — how these figures are produced. Adjust for your specific conditions. A free in-person inspection gives you an exact quote.
Crawlspace Cost Calculator
Answer 6 quick questions for a modeled 2026 Seattle-area price range, before sales tax. How these figures are produced.
This range is a modeled estimate for a Seattle-metro project of this size and scope, before Washington sales tax. Sales tax is added to the full contract price at the rate for your address (10.55% in Seattle from October 1 to December 31, 2026). It is not a quote: actual costs vary with the conditions found and the contractor. Get a free in-person inspection to confirm.