9 crawl space repair services, basement and foundation waterproofing, and the inspection that decides between them. Request a free in-home inspection and get a written, line-item, no-obligation quote.
Each category links to the specific service pages with Seattle-area pricing, signs to watch for, and how the work is done step by step.
What a crawl space inspection covers, what a Washington home inspection is required to report and what it is not, and how to check the registration of whoever goes under the house.
View crawl space inspection details →
View Crawl Space Inspection category →Encapsulation, waterproofing, vapor barriers, drainage, sump pumps, insulation, cleaning, mold remediation and structural repair for crawl spaces around Seattle.
Interior perimeter drains, sump pumps, crack injection, wall membranes and dehumidification for basements around Seattle, with the interior vs exterior comparison.
View basement waterproofing details →
View Basement Waterproofing category →Excavation, exterior membranes, drainage boards and footing drains for new construction, major remodels and hillside lots.
View foundation waterproofing details →
View Foundation Waterproofing category →Start from what you are seeing, not from a product. Each row lists the service that most directly fixes the symptom first, then the others that often come with it — the same order the problem guide uses — with the typical 2026 range for the first fix.
| What you are seeing | Most direct fix | Often also needed | Typical range, first fix |
|---|---|---|---|
| Standing Water | Crawl Space Drainage | Waterproofing, Sump Pump | $4,025 to $7,175 |
| High Humidity | Vapor Barrier Installation | Encapsulation, Waterproofing | $3,400 to $4,675 |
| Visible Mold | Mold Remediation | Encapsulation, Vapor Barrier | $1,600 to $4,025 |
| Musty or Earthy Odor | Mold Remediation | Encapsulation | $1,600 to $4,025 |
| Cold Floors | Insulation Replacement | Encapsulation | $2,500 to $5,825 |
| Sagging or Bouncy Floors | Insulation Replacement | Structural Repair, Drainage, Waterproofing | $2,500 to $5,825 |
| Rodent Evidence | Insulation Replacement | Cleaning, Encapsulation | $2,500 to $5,825 |
| Pest Activity | Insulation Replacement | Encapsulation | $2,500 to $5,825 |
| Water or seepage in a basement | Basement Waterproofing | Foundation Waterproofing, Sump Pump | $7,625 to $16,125 |
| Foundation being dug out, or new construction | Foundation Waterproofing | Drainage | $15,825 to $40,050 |
Not sure which row you are in? That is what a crawl space inspection settles, and it is worth reading what one does and does not establish before you book one.
Modelled 2026 ranges for the Seattle metro, last reviewed November 10, 2026, before Washington sales tax. They are estimates, not collected quotes, and each prices a stated reference project; the methodology sets out how they are produced and what they leave out, and the cost guide takes them apart with the adjustments for size, water and access.
| Solution | What it is for | Typical range | Premium scope |
|---|---|---|---|
| Crawl Space Encapsulation Encapsulation cost breakdown → | Seals the crawl space from outside air and ground moisture, then conditions it | $10,650 to $13,000 | $15,675 to $21,500 |
| Crawl Space Waterproofing Waterproofing cost breakdown → | Drain, sump and ground cover for water getting into a crawl space | $4,025 to $7,175 | $7,625 to $10,650 |
| Vapor Barrier Installation Vapor Barrier cost breakdown → | A ground cover over bare soil: moisture control, not water management | $3,400 to $4,675 | $4,925 to $6,725 |
| Crawl Space Drainage | An interior perimeter drain and sump that collect water and remove it | $4,025 to $7,175 | $7,625 to $14,325 |
| Sump Pump Installation Sump Pump cost breakdown → | Pump, basin and discharge line where water already collects | $1,600 to $3,125 | $2,250 to $4,025 |
| Insulation Replacement | Failed, wet or rodent-damaged floor insulation out, new insulation in | $2,500 to $5,825 | $4,025 to $8,075 |
| Mold Remediation | Containment, removal and treatment of mold on framing | $1,600 to $4,025 | $5,825 to $10,650 |
| Crawl Space Structural Repair | Rotted or failing joists, beams, posts and sills | No modelled range | Set by what the inspection finds |
| Crawl Space Cleaning | Debris, old insulation and rodent contamination removed and the space sanitized | No modelled range | Set by what the inspection finds |
| Basement Waterproofing | Interior drain, sump and wall membrane for a wet basement | $7,625 to $16,125 | $17,925 to $26,875 |
| Foundation Waterproofing | Excavation, exterior membrane, drainage board and footing drain | $15,825 to $40,050 | Beyond the typical range on difficult sites |
| Crawl Space Inspection | Deciding which of the above a house actually needs | In-home inspection is free | A certified home inspection is a separate, paid service |
Structural repair and cleaning carry no range on purpose: how many locations need work, how much has to come out, and whether the load path changes cannot be known without someone under the house, and this site publishes no number it cannot defend. The structural repair page and the cleaning page explain what they can say instead.
Most wasted money in this trade is the right product bought for the wrong problem. These are the five choices homeowners most often face, with the modelled range for each side.
A barrier covers the soil in a crawl space that stays vented; encapsulation seals the vents and the access, runs the liner up the walls and adds a conditioning method. Choose the barrier when the soil is damp but the air is not the problem. Choose encapsulation when humidity, smell or cold floors persist with the soil covered, and not before any liquid water is dealt with.
Vapor barrier vs encapsulation, in full →A pump only removes water that reaches it. If drain lines already bring water to a basin and the pump has failed, the pump is the fix. If water spreads across the soil, it needs a perimeter drain to collect it; crawl space waterproofing is the same drain-and-sump core with a ground cover and crack repair in one scope, at the same modelled range.
Standing water in a crawl space →Decided by what is under the house and where the water is. A crawl space you would have to crawl through is crawl space waterproofing. A below-grade room with a concrete floor is basement waterproofing, usually done from the inside. Exterior foundation waterproofing keeps water off the wall from the outside, and on an existing house it usually makes sense only when the foundation is being dug out anyway.
Interior vs exterior, compared →Cold floors over a vented crawl space are usually an insulation problem, and floor insulation is the part that may qualify for a utility rebate, depending on who heats the house. Encapsulation moves the thermal boundary to the walls of a sealed space instead. If the old insulation failed because the crawl space is wet, fix the moisture first or the new insulation fails the same way.
Cold floors and the crawl space →Remediation removes growth that is already there; it does nothing about why it grew. Without a moisture fix alongside it, it is a repeating expense. The order is diagnosis, then the moisture fix, then remediation of what is left.
Mold in a crawl space →Here's the short version. If your house has a dirt-floor or gravel space under it that you'd have to crawl through, you're in crawl space repair territory. If you have a finished or semi-finished below-grade level with a concrete slab, leaks and seepage point to basement waterproofing. And if you're building, doing a major remodel, or excavating around the foundation anyway, that's the one time exterior foundation waterproofing makes financial sense; nobody digs up a finished yard just to apply a membrane.
One opinion worth stating plainly: don't buy a bigger scope than your symptoms justify. A musty smell with a dry floor doesn't need a sump pump, and a single winter puddle doesn't need a $10,650 to $13,000 encapsulation. A line-item quote exists so you can see which line solves which problem, and you can check the contractor's L&I registration before you sign anything.
Not sure where your house lands? Plenty of homeowners only discover their actual category once someone has been under the house, and a free in-home inspection settles it faster than guessing.
Request a free in-home crawl space inspection and a no-obligation quote for homes in the Seattle metro.
L&I's registration requirement and contractor register, cited in the FAQ, and the sales tax basis for the note on the cost table. The ranges themselves are modelled; see the cost methodology.
Washington State Department of Labor & Industries, Register as a Contractor
Washington State Department of Labor & Industries, Verify a Contractor, Tradesperson or Business
Washington State Legislature, RCW 82.04.050 — “Sale at retail,” “retail sale” (Subsection (2)(b))
Washington Department of Revenue, Construction industry guide: Custom construction Explanatory summary, not the governing text
Washington Department of Revenue, Local sales and use tax rate table (Quarter 4 2026, effective October 1 through December 31, 2026)
Sources last checked between and .
