Giant Builders Seattle
Giant Builders
Beautiful finished basement remodel by Giant Builders Seattle with modern living space, recessed lighting, and luxury flooring
5.0 Rating · 1,000+ Happy Clients · 15+ Years

Seattle's Trusted Basement Finishing & Remodeling Experts

Unlock hundreds of square feet of living space hiding beneath your home. Home theaters, guest bedrooms, wet bars, home offices — all built to code with expert waterproofing and a 5-year warranty.

Licensed (GIANTBS78RZ) · Bonded · Insured · 5-Year Warranty

Get a Free Basement Estimate (425) 757-7872
Google ReviewsYelp ReviewsBBB AccreditedHouzz ReviewsAngi Reviews
1,000+
Happy Clients
200+
Basements Finished
15+
Years in Business
Licensed & Insured

What We Do

Complete Basement Finishing Services

From concept to completion, we handle every aspect of your basement project — so you get the living space you've always wanted without the stress.

Home Theaters & Entertainment Rooms

Soundproofed walls, built-in surround sound wiring, dimmable lighting, tiered seating platforms, and custom media cabinetry. We design basement theaters that rival commercial cinemas — right in your home.

Guest Bedrooms & In-Law Suites

Code-compliant egress windows, full closets, private bathrooms, and separate HVAC zones. We build basement bedrooms and in-law suites that feel like a natural extension of your home — not an afterthought.

Wet Bars & Kitchenettes

Custom cabinetry, countertops, under-counter refrigerators, sinks, and beverage stations. From entertaining guests to a morning coffee nook, we build basement bars and kitchenettes designed for how you live.

Home Offices & Studios

Dedicated electrical circuits, built-in desks, soundproofing, data wiring, and task lighting. We create quiet, productive basement workspaces with proper ventilation and natural light from egress windows.

Rec Rooms & Home Gyms

Rubber flooring, reinforced subfloors for heavy equipment, mirrors, ventilation upgrades, and built-in storage. We build basement gyms and recreation areas designed for daily use.

Waterproofing & Moisture Control

Interior drainage systems, sump pumps, vapor barriers, dehumidification, and proper insulation. Every basement project starts with moisture management — because a dry basement is the foundation of a lasting renovation.

Book a Free Design Consultation

Our Work

Basement Finishing Projects

Browse real basement finishes completed by our Seattle team. Every project started with a free consultation.

Modern finished basement living room with recessed lighting and luxury vinyl plank flooring in Seattle
Basement home theater with tiered seating and built-in surround sound
Finished basement guest bedroom with egress window and custom closet
Basement wet bar with custom cabinetry and stone countertops
Basement home office with built-in shelving and task lighting
Open-concept finished basement with recreation area and kitchenette
View All Basement Ideas See Before & After

How It Works

Our Basement Finishing Process

A clear, structured process refined over 15+ years — so you always know what's next.

01

Free Consultation

We visit your home, inspect the basement conditions, take measurements, discuss your goals and budget, and provide honest advice — not a sales pitch.

02

Design & 3D Renderings

Our in-house designer creates detailed plans with photorealistic 3D renderings so you see your finished basement before we build it.

03

Permits & Materials

We handle all Seattle building permits — including egress window permits — and help you select every material, fixture, and finish.

04

Build & Finish

Your dedicated project manager oversees waterproofing, framing, electrical, plumbing, drywall, flooring, and finishing. Daily progress updates keep you in the loop.

05

Final Walkthrough & Warranty

We walk through every detail together. The job isn't done until you're completely satisfied. Then your 5-year workmanship warranty begins.

$35K–$100K+
Typical Seattle Basement Finishing Range
70%
Average ROI on a Basement Finish
6–12 Wk
Typical Construction Timeline

Why Seattle Homeowners Choose Giant Builders

We handle every detail so you enjoy the results — not the stress.

Transparent Fixed Pricing

Your written quote is your final price. Detailed line-item estimates with no hidden fees or surprise change orders.

Expert Waterproofing

Comprehensive moisture management on every project. Drainage, vapor barriers, insulation, and sump pumps that keep your basement dry for decades.

Dedicated Project Manager

One point of contact from design to completion. Daily progress updates so you're always in the loop.

5-Year Warranty

Our industry-leading workmanship warranty protects your investment long after the last wall is finished.

The Giant Builders Difference

Included With Every Basement Finish

Dedicated project manager
Professional in-house designer
3D basement renderings
5-year workmanship warranty
Licensed & insured crew
Transparent pricing — no hidden fees
Daily progress updates
Full permit handling
Post-project cleanup & inspection
Material selection assistance
Moisture assessment & waterproofing
Egress window coordination

What Our Clients Say

Hear from Seattle homeowners who transformed their basement with us.

Google Verified

“Our basement was a dark, damp storage pit. Giant Builders waterproofed the space, added egress windows, and turned it into a guest bedroom, full bathroom, and home theater. It added over 800 square feet of living space. Our home value jumped significantly — best investment we've made.”

Michael & Karen W.
Full Basement Finishing, Ballard
Google Verified

“I wanted a dedicated home office with soundproofing and proper lighting. Giant Builders designed the perfect layout with built-in shelving, a separate HVAC zone, and even wired it for ethernet. I can take video calls down there without any noise from upstairs. Incredible work.”

Tom R.
Basement Home Office, Capitol Hill
Houzz Verified

“We needed an in-law suite for my mother. Giant Builders handled the egress windows, kitchenette, full bathroom, and separate entrance. They managed the permits and inspections seamlessly. My mom loves her new space and we love having her close. The crew was professional and clean every day.”

Amanda & Chris L.
Basement In-Law Suite, Bellevue
Read More Reviews

Basement Finishing FAQ

Common questions about basement finishing and remodeling in Seattle.

How much does basement finishing cost in Seattle?
Basement finishing in the Seattle area typically ranges from $35,000 for a basic single-room finish to $100,000+ for a full basement build-out with a bathroom, kitchenette, and bedroom. Projects with complex waterproofing, egress windows, or full in-law suites tend to fall in the $60,000–$120,000 range. Seattle projects run about 15% higher than the national average due to local labor rates and permit requirements. We provide a detailed, line-item estimate during the design phase so there are no surprises.
How long does it take to finish a basement?
Most basement finishing projects take 6 to 12 weeks of construction, depending on scope. A single-room conversion may take 4 to 6 weeks, while a full basement build-out with a bathroom, bedroom, and kitchenette can take 10 to 14 weeks. The design and permitting phase adds 3 to 6 weeks before construction begins. We give you a detailed timeline during your consultation.
Do I need permits to finish my basement in Seattle?
Yes. Finishing a basement in Seattle requires permits from the Seattle Department of Construction & Inspections (SDCI) for any work involving framing, electrical, plumbing, or egress modifications. Adding a bedroom requires a code-compliant egress window. We handle all permit applications, plan reviews, and inspections for you — it's included in our service.
Does my basement need egress windows?
If you're adding a bedroom or sleeping area to your basement, Seattle building code requires at least one egress window per bedroom. Egress windows must meet specific size requirements (minimum 5.7 square feet of opening) and the window sill cannot be more than 44 inches above the floor. We handle the full egress window installation, including excavation, well construction, and waterproofing.
How do you handle basement moisture and waterproofing?
We start every basement project with a thorough moisture assessment. Our waterproofing approach includes interior drainage systems, sump pump installation (if needed), vapor barriers on walls and floors, rigid foam insulation, and dehumidification planning. Proper moisture management is the most critical step — it prevents mold, rot, and musty odors that can ruin a basement finish.
Can I add a bathroom to my basement?
Yes. Adding a basement bathroom is one of the most popular upgrades. If your home has a sewer line at or below basement level, we can tie in directly. If not, we install an upflush or sewage ejector pump system. We handle all the plumbing, waterproofing, tile work, and fixture installation.
Can I build an in-law suite or rental unit in my basement?
Yes. Many Seattle homeowners finish their basement as an in-law suite, guest apartment, or rental unit. We design spaces with separate entrances, kitchenettes, full bathrooms, and code-compliant egress. Seattle's ADU regulations allow flexibility for how you use the space. We handle all permitting and ensure the layout meets local requirements.
Can I stay in my home during basement finishing?
Yes. Most homeowners remain in their home during basement construction. We contain dust and noise as much as possible with barriers and a clear work schedule. Your dedicated project manager will coordinate access and minimize disruption to your daily routine.
What areas do you serve?
We serve Seattle and the greater Puget Sound area, including Bellevue, Kirkland, Redmond, Renton, Bothell, Woodinville, Issaquah, Sammamish, Mercer Island, Shoreline, Lynnwood, Edmonds, and surrounding communities.

Basement Finishing Serving Seattle & the Greater Puget Sound

Seattle·Bellevue·Kirkland·Redmond·Renton·Kent·Tacoma·Federal Way·Bothell·Woodinville·Issaquah·Sammamish·Mercer Island·Burien·Shoreline·Lynnwood·Edmonds·Auburn·Tukwila·SeaTac

Ready to Finish Your Basement?

Start with a free consultation. Tell us about your project and we'll reach out within 24 hours.

Free estimate · No obligation · Response within 24 hours

Prefer to talk? Call us directly:

(425) 757-7872