Basement Waterproofing cost in Seattle, WA
Seattle, WA · updated August 2026
$10,600
Typical local cost
$3,900 – $23,200
Typical range
- per linear foot of drain installed
- $50 – $200
- Permit
- It depends
- Typical timeline
- 2-5 days of work
Installed, local pricing
$0 – $540 in fees
2-5 days of work
Seattle runs +29% against the U.S. average · data confidence Medium · modeled estimate, not a quote
The modeled midpoint for Seattle is $10,600. The local adjustment for this trade is x1.287 — driven mainly by King County labor rates and 20% exposure to local code requirements.
Cost by project size
Generated from the same unit pricing the calculator uses.
| Project size | Estimated range |
|---|---|
| 45 linear foot of drain installed | $2,300 – $9,000 |
| 60 linear foot of drain installed | $3,000 – $12,000 |
| 75 linear foot of drain installed | $3,800 – $15,000 |
| 100 linear foot of drain installed | $5,000 – $20,000 |
| 130 linear foot of drain installed | $6,500 – $26,000 |
Based on Seattle pricing of $50–$200 per linear foot of drain installed.
Where the money goes
- Labor
- $5,800
- 53% of median
- Materials
- $4,800
- 44% of median
- Permit & fees
- $270
- 2% of median
Seattle project costs+29% vs U.S. average
Based on King County labor rates, local material logistics and permit-fee posture for this trade.
What the project looks like start to finish
Typical sequence for this scope. Timing varies with contractor backlog and plan-review queues.
01
Planning & quotes
Scope, material choice, contractor selection
02
Permit application
Filed with City of Seattle building department
03
Materials & staging
Order lead time on non-stock materials
04
Installation
2-5 days of work
05
Inspection
Plumbing inspection where a sump discharge is added
06
Closeout
Final sign-off, warranty and documentation
Seattle labor intelligence
What the trade charges here, and how much of your price it is.
Loaded hourly rate
$97–$125
Structural crews in King County · +34% vs U.S. ($82/hr)
Typical crew
3 × 2 days
On-site time for a typical waterproofing job here.
Labor in the price
$5,800
55% of the median — the rest is material, disposal and permit.
Because labor is 55% of this job, Seattle wage levels move the price far more than material prices do. A quote well under this labor figure usually means a smaller crew, a longer schedule, or unlicensed help.
Basis: Hometriva labor model: national structural crew rates adjusted by the King County labor factor (x1.338). · BLS Occupational Employment and Wage Statistics, Hometriva methodology
Why Seattle differs from the national average
The local delta, broken into dollars by driver.
Trade labor rates+$1,525
King County crews price 34% above the national average, and labor is 55% of this job.
Material and delivery+$575
Materials are nationally traded, so they move less — but delivery into this market runs 15% over baseline.
Code and inspection load+$200
Basement Waterproofing carries 20% exposure to local code requirements, and this jurisdiction's review load indexes at x1.13.
Permit fees+$75
Fees are paid to the jurisdiction, not the contractor, and are budgeted separately from the contract price.
Basis: Decomposition of the modeled Seattle median against the U.S. median for this scope. · City of Seattle building department, Hometriva methodology
Seattle vs Washington vs the U.S.
Change the inputs, see your number
The same local model, run against your job instead of the average one.
Simulated basement waterproofing in Seattle
$10,870
Likely range $4,170 – $23,470
Simulated from the same local model as the numbers above — it changes the inputs, not the pricing method.
What makes the number move
- Interior drain tile versus exterior excavation and membrane
- Linear feet of wall treated and the number of sump pits
- Concrete breakout and replacement inside the slab
- Battery backup or a second pump for redundancy
- Grading, downspout extension and window well work outside
Who issues each permit
Tracked per discipline — the building permit issuer is not always the body that reviews electrical, plumbing, zoning or fire.
| Discipline | Issuing authority |
|---|---|
| building | City of Seattle building departmentModeled estimate |
| electrical | City of Seattle building departmentModeled estimate |
| mechanical | City of Seattle building departmentModeled estimate |
| plumbing | City of Seattle building departmentModeled estimate |
| zoning | City of Seattle building departmentModeled estimate |
| fire | City of Seattle building departmentModeled estimate |
Permit requirement in Seattle
It depends on scope. Like-for-like cosmetic work in Seattle is often exempt, but a permit is required as soon as you change structure, plumbing, electrical or the building envelope.
- Permitting authority
- City of Seattle building departmentModeled estimate
- Permit fee
- Estimated allowance $0–$540Modeled from comparable fee schedules — not an official quoted fee.
Inspections
- Plumbing inspection where a sump discharge is added
Local conditions that change this job
Only the exposures that materially affect basement waterproofing.
Cooling load / heat exposure
Moderate44/100
Humidity
High70/100
Named-storm exposure
Low34/100
SDCI review timelines, seismic detailing and energy-code requirements add meaningful cost and schedule to structural and envelope work.
Nearby market comparison
What Seattle homeowners actually paid
Homeowner-reported invoices for this market. Nothing is published until enough reports clear review, so this section is often empty in newer markets — adding yours takes 20 seconds and no personal details.
Quotes homeowners were given in Seattle
Quotes run ahead of final invoices. Reporting yours shows the local spread and where there is room to negotiate.
How Hometriva estimates Seattle waterproofing costs
Hometriva does not publish invented city prices. The Seattle estimate for basement waterproofing is produced by this chain, and every input is stored separately:
- National baseline$8,200
Typical U.S. cost for basement waterproofing on a single-family home.
- Local labor factorx1.338
Seattle-area trade labor rates, weighted at 55% of this job.
- Material factorx1.153
Material and delivery pricing into King County, weighted at 45%.
- Regulatory factorx1.128
Local code, product-approval and inspection load, applied at 20% for this project type.
- Applied multiplierx1.287
Blended Seattle adjustment specific to basement waterproofing.
- Permit component$0 – $540
Budgeted separately from the contract price because it is paid to the jurisdiction.
Because labor, material and regulatory factors are weighted per project, basement waterproofing in Seattle carries a different local adjustment than other trades in the same market.
Reviewed by
Hometriva Cost Data Desk
Maintains the unit-cost baselines, local adjustment factors and material pricing. Reviewed for basement waterproofing pricing in Seattle, WA.
- • National unit-cost baselines against current trade pricing
- • Local labor and materials factors for the market
- • Material installed-cost ranges and service life
Last reviewed August 2026 · Editorial standards · Report an error
Frequently asked questions
Is a permit needed to waterproof a basement?
Interior drainage is often treated as maintenance, but adding a sump discharge, altering plumbing or excavating against the foundation usually triggers a permit. Ask the local building department before work starts.
Does interior drainage fix the cause?
It manages water that has already reached the wall. When the cause is grading, gutters or a downspout discharging beside the foundation, correcting that outside is cheaper and should come first.
How long does basement waterproofing take?
2-5 days of work. Permit review and inspection scheduling are usually the largest source of variation.
What changes the price the most?
The largest cost drivers are interior drain tile versus exterior excavation and membrane; linear feet of wall treated and the number of sump pits; concrete breakout and replacement inside the slab.
Sources
Sources & verification
- City of Seattle building department
- Seattle permit portal
- Washington State Building Code Council
- BLS Occupational Employment and Wage Statistics
Model vintage August 2026. The links above are the issuing agencies' own pages — we publish them so you can confirm the current rule yourself, not as evidence that each fact on this page was re-checked with them today. Cost figures are modeled estimates based on national baselines adjusted for local labor and material pricing, not quotes. Permit rules change; confirm with the building department before starting work.