Garage conversion, Greater Seattle Area
7 Tips for Converting a Garage Into a Bedroom and Bathroom
Converting a garage into a bedroom and bathroom starts at $110,000+ with us for a typical 2 car garage, or $75,000+ without the bath. In the Seattle area it needs a building permit, a ceiling of at least 7 feet, an escape window, insulation to the energy code and fixed heat. A family room or office starts at $60,000+.
The seven tips below follow the order we plan one in. To have your own garage measured and priced in writing, Book a Consultation.
Tip 1: Can your garage legally become a bedroom?
Yes, if it meets the code minimums for a sleeping room. The 2021 Seattle Residential Code, Chapter 3 sets them. A typical 2 car garage, about 400 to 480 square feet, clears the 70 square foot minimum many times over. The ceiling height over a raised floor and the escape window are what need measuring.
| Rule | Section | What it requires |
|---|---|---|
| Ceiling height | R305.1 | At least 7 feet in habitable rooms; 6 feet 8 inches in bathrooms |
| Room size | R304.1, R304.2 | At least 70 square feet, and at least 7 feet in any horizontal direction |
| Natural light | R303.1 | Glass area of at least 8 percent of the floor area |
| Escape opening | R310.1, R310.2 | One operable opening per bedroom: 5.7 square feet clear (5 at grade floor), 24 inches high, 20 inches wide, bottom no more than 44 inches above the floor |
| Smoke alarm | R314.3 | One in each sleeping room |
| Garage beside the bedroom | R302.5.1 | No opening from a garage directly into a sleeping room |
Source: 2021 Seattle Residential Code, Chapter 3, read October 2026. Other cities adopt their own editions; we check yours before design.
Tip 2: Do you need a permit to convert a garage in Seattle?
Yes. Section R105.1 of the 2021 Seattle Residential Code requires a building permit "prior to erecting, constructing, enlarging, altering, repairing, moving, improving, removing, changing the occupancy of, or demolishing such building or structure". A garage that becomes a bedroom changes from storage to living space, and the electrical and plumbing work need their own permits.
Permits come from the city the house is in: the Seattle Department of Construction and Inspections in Seattle and Development Services in Bellevue. Some cities also check that you keep enough parking. A bedroom built without a permit can surface later, often when the house is sold. For what else needs a permit, read Do you need a permit to remodel in Seattle?
Tip 3: How do you fix a sloped garage floor for a bedroom?
Build a new floor over the slab. Garage slabs are poured with a slope toward the door and usually sit below the floor of the house. We level the floor, put a moisture barrier and insulation over the concrete, and bring it up to meet the house where the two rooms connect.
Check the height first. A raised floor eats into the ceiling, and the room still needs 7 feet under R305.1. A cracked slab, or a floor that has to rise a long way to meet the house, adds work before framing starts. Raising the slab or adding a subfloor is outside our starting prices and priced in writing when a project needs it.
Tip 4: What insulation and heat does a garage conversion need?
Full energy code insulation and fixed heat. Under Section R502.2 of the Washington State Energy Code (WAC 51-11R-50200, effective March 15, 2024), a garage that becomes heated space must meet the whole code. The R-values, the floor and the wall where the big door was are covered step by step in How to Insulate a Garage: A Step-by-Step Guide.
Skip the space heater. Section R303.10 of the 2021 Seattle Residential Code requires heat that can hold 68°F in habitable rooms and bathrooms, and says "The installation of one or more portable space heaters shall not be used to achieve compliance with this section." Our conversions use a heat pump or electric heat, and a bedroom gets its own heat zone.
Tip 5: What replaces the garage door on a converted garage?
A framed wall, usually with a window or an entry door in it. The big door comes out, the opening is framed and insulated, and the outside is sided and trimmed to match the house. On a bedroom, this new wall can hold the escape window from Tip 1: R310.1 requires that opening to lead to a yard, court or public way, and the old door usually faces the driveway.
Place the windows for the light rule too. For a 400 to 480 square foot garage, 8 percent glass under R303.1 means about 32 to 38 square feet of window. Seattle's edition struck the openable window rule from R303.1. R303.4 requires exhaust fans and whole house ventilation instead. We plan the fans with the heat.
Tip 6: How do you add a bathroom to a garage conversion?
Cut the slab for the drains. Water and drain lines are cut into the concrete and tied into the house plumbing, with a pump where the drain cannot fall to the sewer. How far the garage sits from those lines, and how deep the sewer runs, sets much of the plumbing cost. The bath fan vents outside.
Moving the water heater or laundry out of the garage is a separate line on the price. Have the electrical panel checked at the first visit too, because a panel upgrade is priced on its own line when the new loads need one. Our Redmond basement bathroom shows the bathroom side of the work: rough plumbing, tile and a double vanity in about 12 weeks in 2024. It cost about $100,000.
Tip 7: Should you plan the garage conversion as a future ADU?
Decide before the drawings. A bedroom and bath is part of the house. A legal accessory dwelling unit (ADU) also needs its own kitchen, its own entrance and fire and sound separation from the house. Plumbing and a separate thermostat are much easier to plan in than to add later. Under the 2021 Seattle Residential Code (interpretation of R303.10), an ADU gets heating controls separate from the main house.
In Seattle, a unit in an attached garage is an attached ADU, and a converted detached garage is a DADU. Seattle does not apply its parking standards to ADUs. A garage conversion ADU starts at $150,000+ and takes 3 to 5 months on site after design and permits. The difference between the two types is in ADU vs DADU in Seattle, WA: What Is the Difference?
How much does it cost to convert a garage into a bedroom and bathroom?
A garage to bedroom with a full bath starts at $110,000+ with us, and a bedroom without a bath at $75,000+. These are the starting prices on Garage Conversion Across the Greater Seattle Area, for a typical 2 car garage:
| Room | Basic | Mid-Range | Luxury | Time on site |
|---|---|---|---|---|
| Family room or office | $60,000+ | $80,000+ | $110,000+ | 6 to 9 weeks |
| Bedroom | $75,000+ | $100,000+ | $135,000+ | 8 to 11 weeks |
| Bedroom with full bath | $110,000+ | $140,000+ | $180,000+ | 10 to 14 weeks |
Source: Volcano Builders garage conversion prices, October 2026. Time on site comes after design and permits. Design, engineering, survey and permit fees, panel upgrades and moving the water heater or laundry are priced separately.
What did a similar bedroom cost on our own jobs?
Our Finished Basement Remodel in Seattle, WA, completed in July 2024, cost about $120,000. It added clothes and storage closets and one oak-look plank floor through the level. The bedroom side, behind glass-paned French doors, is now a main bedroom suite. A garage bedroom needs the same finish work: closets, one continuous floor and trim.
Every conversion carries a 2-year workmanship warranty, which can be extended to 5 years. For remodeling in the city, see Home Remodeling Contractors in Seattle, WA.
Should you convert a garage yourself or hire a contractor?
Hire licensed trades for the parts inspectors check: the wiring, the plumbing, the escape window and the energy code work. The building, electrical and plumbing permits each come with their own inspections.
We visit, measure the garage and check the ceiling height, the slab and where water, sewer and power can reach. Then we draw the room, price it line by line and file the permits. One project manager runs the work through the framing, insulation and final inspections.
Frequently Asked Questions
Does a garage conversion add value to a house?
It adds finished living space, which appraisers count when it is permitted and matches the rest of the house.
Can I keep part of the garage for parking or storage?
Yes, with a wall between them. Section R302.5.1 of the 2021 Seattle Residential Code does not allow an opening from a garage directly into a sleeping room. The door rules for the rest of the wall are in our garage insulation guide.
Is a detached garage harder to convert?
It usually needs more site work. A detached garage may need a new electrical feed and a water line run across the yard.
Should we convert the garage or build an addition?
Convert when the garage is sound, tall enough and you can give up the parking, because the foundation, walls and roof are already there. Build out or up when you need to keep the garage or want a larger room.
