Home / Services / Basement remodeling / Waterproofing
Bellevue & the Eastside · Basement waterproofing contractor
Interior French drains, sump pumps and vapor barriers that keep groundwater out, installed by the same team that will finish the space, for one fixed price.
In-house crews · Licensed, bonded & insured in WA · Permits handled for you
Waterproofing at a glance
Typical cost
$10k – $25k
System
French drain + sump pump
When
Before any framing
First step
Moisture check
Licensed
Bonded & insured in WA
In-house
Crews for the core trades
3D design
See it before we build it
Permits
Filed and managed by us
The short answer
Basement waterproofing on the Eastside, with an interior French drain and sump pump, usually costs $10,000 to $25,000. A damp basement can usually be finished once the water is under control. We find where the water comes from, install the drain and pump, add a vapor barrier where needed, and only then start framing.
Reviewed by John, project lead · Prices from our 2026 Seattle-metro basement cost guide · Updated October 2026
More basement services
Once the basement is dry, turn it into a family room, bathroom, suite or theater.
Framing, insulation, drywall, flooring and lighting that turn bare concrete into living space.
$30k – $55k
4–6 week build
Basement finishing →
A full or three-quarter bath added below grade, with the drain and pumping worked out first.
$55k – $95k
With full finish
Basement bathrooms →
A bedroom, bathroom and egress window, or a fully separate basement ADU with its own entrance.
$75k – $140k
Permit required
Basement ADUs →
Sound-insulated walls, tiered seating, projector or big-screen wiring and dimmable lighting.
$35k – $70k
Wired for your system
Home theaters →
Code-compliant escape windows with excavation, window well and ladder, required for any basement bedroom.
$8k – $18k
Per window
Egress windows →
Compare every basement project we build, side by side, with costs.
$30k – $140k
Moisture check first
All basement services →
Basement waterproofing on the Eastside
A moisture check, a trench cut along the inside of the foundation, perforated drain pipe in gravel, a dimple membrane on the walls, a sealed sump basin with a pump and discharge line, and a patched slab. Where needed we add exterior drainage and vapor barriers.
Eastside basements sit in wet soil for months each year, and water is the most common reason a finished basement fails. A working drain and pump comes before any drywall.
When the designer and the builder are the same company, the drawings are priced as they're drawn. You never pay for a design you can't afford to build, and change orders drop because the crew helped plan the job.
✓
Moisture check before design
✓
3D render of your new basement
✓
Egress windows for every bedroom
✓
Permits filed and inspections handled
✓
In-house crews, one project lead
Code and permits
Basic finish · 4–6 wk build
Full or 3/4 basement bath
In-law or guest suite
Home theater and media room
Wet bar and game room
Home gym or office
Egress windows for bedrooms
French drain and sump pump
How it works
01
First visit
We visit, measure, check ceiling height and look for signs of water before anything else.
02
Design
We lay out rooms around beams, ducts and the stairs, show it to you in 3D and lock in a fixed price.
03
Permit
We file the permit and, if needed, install the drain and sump pump before framing starts.
04
Build
Framing, rough-in, inspections, insulation, drywall, flooring and trim. A basic finish takes about 4 to 6 weeks.
05
Final
We walk the final inspection, checking egress windows, smoke detectors and lighting, then go through the punch list with you.
Typical projects
Guest suite
A guest bedroom with a code-compliant egress window, a closet and a new bathroom down the hall.
$75k – $140k
Permit required
Rec room
An open rec room with a wet bar, open shelving and space for a pool table, plus a powder room.
$55k – $95k
Finish + bath
Basic finish
Bare concrete finished with rubber flooring, a mirror wall, insulated walls and a storage room for seasonal gear.
$30k – $55k
4–6 weeks
Reviews
Real Google reviews from homeowners we've built for across Bellevue and the Eastside.
FAQ
Straight answers on cost, permits, egress and moisture. Ask us anything else at the free consult.
How much does basement waterproofing cost?
An interior French drain and sump pump usually costs $10,000 to $25,000 on the Eastside. The length of wall, slab thickness and how much water you're dealing with move the number most.
Do I need waterproofing before finishing my basement?
If we find signs of water, yes. Finishing over a wet wall traps moisture behind the drywall. We check every basement first and only recommend a drain and pump when it needs one.
Do I need a permit to finish my basement?
In nearly all cases, yes. Egress windows, new electrical circuits and plumbing all need permits in Bellevue and the rest of the Eastside. We file them and handle the inspections.
Does a basement bedroom need an egress window?
Yes. A basement room can't legally be used or sold as a bedroom without a code-compliant egress window. Each one costs $8,000–$18,000, including excavation and the window well.
How tall does my basement ceiling need to be?
Habitable rooms need about 7 feet of ceiling height, with limited exceptions for beams and ductwork. We measure it at the first visit.
Can you finish a damp basement?
Usually, yes, once the moisture is fixed. If groundwater is the problem, we install an interior French drain and sump pump first, which typically costs $10,000–$25,000.
Is finishing a basement worth it?
Per Remodeling magazine's Cost vs. Value data, Seattle-area basement conversions typically return 65–75% at resale. With Eastside homes at $1.2 to $2.5 million, finished square footage adds real value.
Start with a dry basement
Tell us about your basement. We'll visit, check moisture and ceiling height, talk through layout and budget, then send you a fixed price.
Renovision Design & Build LLC
1400 112th Ave NE, Bellevue, WA 98004
(425) 276-6501 · Mon–Fri 8–5
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