Getting a permit feels like the finish line, but it is really the starting gun. Once SDCI issues the permit, the project moves into the field, and the city keeps watch through a series of inspections. Knowing the DADU construction stages helps you follow progress and understand why no one can skip certain steps.

This guide walks through what happens after approval, in the order the Seattle Residential Code and SDCI describe. It focuses on the official steps rather than time estimates, since every site is different.

Before Any Work Begins

A few things must be in place before the first shovel hits the ground. According to Section R106 of the Seattle Residential Code, work requiring a permit cannot start until the permit holder posts an inspection record in a visible spot on the site. That record stays in place until final approval.

The permit also has a clock. Under the same code, authority to do the work expires eighteen months from the date of issuance. An approved renewal extends it for another eighteen months, so steady progress protects the permit.

The approved plans matter too. The code says they must stay at the site for inspectors during the work. Also, the permit holder or an agent must request each inspection. SDCI’s construction inspections page explains how to schedule them online or by phone.

Site Setup and Erosion Control

The first field stage protects the ground and nearby properties. Under the same section, the first ground disturbance inspection happens before any land disturbing work. It follows the installation of erosion control measures and any required fencing for buffers.

SDCI notes that this visit verifies the erosion control method and checks site plan conditions. It may also include a preconstruction meeting. Tree protection, if required, belongs in this stage as well. For more on temporary runoff control, see our guide to DADU site drainage.

Foundation Among the First DADU Construction Stages

Next comes the foundation. The code calls for a foundation inspection once crews dig the trenches, set the forms and have the foundation materials on site. Where crews use ready mix concrete, those materials do not need to be on the job yet.

For slabs and raised floors, another check follows. The concrete slab or under floor inspection takes place once in slab or under floor equipment, conduit and piping are in place. It happens before the pour or before floor sheathing goes down. Our post on DADU foundation types explains the common options.

Framing and Rough Systems

With the base set, the cottage takes shape. Crews frame walls, floors and the roof. Meanwhile, electricians, plumbers and mechanical installers run their rough work through the frame.

The frame inspection comes after the roof, framing, fireblocking and bracing are in place. By then, pipes, chimneys and vents should be complete, and the rough electrical, plumbing and heating work must have its own approvals. SDCI’s inspection page lists sub floor and structural checks as possible steps too.

At each visit, the inspector either approves that portion of the work or tells the permit holder what fails to comply. In that case, the crew corrects the issue and requests another look before moving on.

Related Permits Run Alongside

The building permit is not the only one in play. According to SDCI, mechanical, electrical, plumbing, side sewer and water services require separate permits and separate inspections. Each trade follows its own process while the main work continues.

For example, Public Health Seattle and King County inspects plumbing and gas piping in Seattle. City Light and SPU also have roles in power and water service. Coordinating these visits keeps the main schedule moving. Otherwise, one missing trade approval can hold up the next building inspection.

Insulation and Wall Coverings in DADU Construction Stages

Once rough systems pass, the walls get insulation. The code’s insulation inspection takes place after insulation and vapor barriers are in place, but before any gypsum board or plaster goes on. This is the last look inside the walls.

Some cottages also need a gypsum board or lath inspection for shear walls. It happens after the boards go up but before anyone tapes and finishes the joints. After that, interior finishes, cabinets and fixtures follow.

The Rule About Covering Work

One principle runs through every stage. The code says work must stay accessible and exposed for inspection until the building official approves it. In addition, it states that no work may go beyond each inspection point without written approval.

Skipping ahead can be costly, and the code explains why. If someone covers work too early, the crew may have to remove material so an inspector can see it. That is why the sequence matters so much.

Return visits carry a cost as well. Under the code, the building official may assess a reinspection fee when work calls for another visit. Our guide to DADU building inspections goes deeper on each visit.

Final DADU Construction Stages and Occupancy

The last stages bring everything together. The code includes a final site inspection once crews finish grading, permanent erosion control and stormwater work. SDCI’s final inspection follows after construction is complete and all related permits have their own finals.

Only then can people move in. The code states that no one may occupy a new building until the building official approves it for occupancy after final inspection. Overall, the DADU construction stages follow a clear order, and each approval opens the door to the next step.