From Garage to Accessory Dwelling Unit

ADUs (Accessory Dwelling Units) are becoming more popular than ever for multiple reasons. Over the last few years, some municipalities have made it easier for homeowners to install ADUs.

For example, Seattle’s Mayor, Jenny Durkan, signed legislation in 2019 to remove regulatory barriers and make it easier for property owners to create ADUs in Seattle’s single-family zones. Seattle has ten pre-approved plans that they claim the permitting department only needs 30 days to approve to issue a permit.
Our latest ADU project was on the outskirts of Issaquah in unincorporated King County, which had its own permitting challenges. The homeowner was interested in building an ADU in their massive, detached garage to have a place for his parents to stay while visiting their grandchildren. There was talk early on about having a ramp, but they opted for simple stairs at the front door that a ramp could easily replace in the future if the need arose. Then, later down the road, when the grandparents need more attention, they would move in permanently.

The initial step was designing the space and submitting drawings and engineering to obtain a permit as soon as possible. The client decided to wait to choose the finishes until the permit was approved. Because of this choice, they were under a time crunch that caused them to rely on the items in stock at the box stores to finish off the spaces.

Through the permitting process, we dovetailed our work with the septic contractor that the client hired before Shirey Home Pro came on board to add a secondary drain field for the ADU.

Then, a challenge arose from the Fire Marshal’s office: They said that fire sprinklers were required. There was no feasible way to push enough water up the hill to meet the gallons-per-minute requirement for the sprinkler system. The best option was to install a 425-gallon tank and pump in the garage. However, the tank needed to be placed in a heated, insulated space and the ADU water lines. Then, we were required to add a sprinkler head in the tank and pump storage cabinet.
When you build an ADU or a room inside a garage, you need a foundation around all sides. Even though you are not supporting a roof, you support the floor and walls. Concrete slabs are typically 4’ thick, but the earth below may be less than ideal, so inspectors won’t risk letting you build on the slabs. Therefore, we cut and removed the concrete necessary to form and pour footings and stem walls. Along with cutting the slab, we also cut the existing stem walls to vent the crawlspace.

The nice thing about working inside the garage was that we didn’t have to worry about the weather. The framing and mechanical rough-ins went as scheduled. We found ourselves waiting for the engineered fire sprinkler plan final approval.
Once we returned, we commenced the work on the insulation and drywall. We placed 5/8 drywall up and through the roof trusses to separate the ADU from the garage. We installed new high efficient windows in the existing and new window openings.

We were in the home stretch. All we had left were the finishes. We installed a brown and gray engineered floor in the main spaces, Marmoleum in the bathroom, 5-dark panel doors, and a white base and case in every room. The clients went with simple shaker cabinets in the kitchen paired with floating shelves made by the client. Once the cabinets were in place, we templated and installed the countertop and sink.

The clients made an early selection for the bath vanity combo, so Shirey Home Pro ordered and stored it safely until the space was ready. We installed the client-selected tile on the kitchen backsplash and shower walls. The last finish to be installed was the glass for the shower.

All in all, the project was a success! The result, the ADU looked was functional and beautiful.
If you would like to schedule a visit to your home to discuss adding an ADU to your property, don’t hesitate to get in touch with us.

View this project start to finish
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