Prove What a Seattle Garage Can Become Before Pricing the Conversion

Garage and basement projects are often called simpler because the roof and walls already exist. That skips the main question. A storage building may not be dry, warm, sound or ready for year-round living.

Reconcile records with the physical building

Collect assessor details, permits, old plans and owner records. Check whether the building’s location, size and use match those records. Note later changes, filled openings, added utilities and work with no clear approval.

A missing document does not always stop the project. The design team must still identify any work that needs more review or legal approval.

Commission a conversion-focused inspection

A walk-through should record what can be seen and what needs more review. It should not make a casual promise that the conversion is easy. Photograph and record:

• cracks, settlement and slab level.
• moisture, drainage and contact with surrounding soil.
• wall and roof framing condition.
• ceiling height and obstructions.
• door and window openings.
• proximity to the main home and property edges.
• current power, water, waste and heating.
• safe work access around the occupied property.

If finishes hide an important area, state when it will be opened and who will review it.

Decide whether the slab belongs in the future dwelling

The current floor may lack insulation, moisture control or the right height. It may also block a practical sewer route. Lowering or rebuilding it can affect the foundation and doors. Cutting it for pipes creates repair and structural questions.

Ask the designer and builder to show the planned finished floor, moisture strategy and below-slab service work. A line reading “use existing slab” needs supporting review.

Evaluate the shell for residential performance

Garage walls and roofs may not meet home standards. Check the frame, outer panels, joints, rot and pest damage. Make sure new insulation will not trap moisture. A large garage-door opening needs a planned wall and foundation detail.

In Seattle’s wet climate, exterior grade, roof runoff and flashing deserve early attention. A conversion should not hide water entry behind a newly finished interior.

Plan light, escape and independent access

Draw the rooms and furniture, not just walls. Check ceiling height, daylight, airflow, emergency escape and the entry. New doors or windows may need structural work and may affect privacy or movement through the yard.

For a basement, check stairs, headroom and below-ground moisture. For a detached garage, show the path from the street or alley. Make sure people can reach the unit safely at night and in wet weather.

Define fire, sound and household privacy

Fire rules depend on how the buildings connect. Mark walls, floors and openings that need protection. Add safe details around pipes, wires and alarms. Plan sound control around bedrooms, living rooms, plumbing and equipment.

If work touches the main home, put the work order and temporary protection in the contract. State which rooms will be closed. Explain how the team will control dust, weather and security.

Test service routes without assuming proximity equals ease

Nearby utilities can help. But capacity, elevation and access still matter. Record the electrical source, anticipated loads, water route, sewer connection and ventilation or heating approach. Show where trenches or slab cuts occur and who repairs them.

The Seattle utilities guide turns those assumptions into bid items. A short pipe run is not a saving when it requires major work inside the occupied dwelling.

Compare conversion, rebuilding and another ADU type

Prepare three conceptual totals where evidence is uncertain:

1. Retain most of the shell and correct the listed defects.
2. Keep only selected portions or rebuild on the location.
3. use an attached or new detached unit elsewhere.

Include the value of lost parking or storage and the effect on outdoor space. The lowest initial building number may not be the best household result.

Require drawings of current and planned conditions

The plans and price should show what stays, what goes and what is new. Include floor and roof details, structural changes and moisture control. Add fire details, insulation, windows, doors and building systems.

When review continues after pricing, mark the affected work as an allowance or defined extra budget for surprises. Do not bury every unknown under a broad change-order clause.

Build a conversion budget from retained value

Company ads may quote a floor area without saying which upgrades are included. Use separate budget lines for records, design, permits and demolition. Add structural and moisture repairs, shell upgrades, systems, kitchen, bath, finishes and outside repairs.

The Seattle cost guide provides a whole-project structure. Remove only the elements the inspection supports as genuinely reusable.

Ask for evidence from similar conversions

Check the builder through Washington L&I. Then ask for similar garage or basement projects. Ask what the team inspected, what hidden damage it found and how the contract handled it. New DADU work alone does not prove conversion skill.

Use the builder comparison to check entity identity, permit duty and the written risk allocation.

Preserve the basis for the choice

Save photos, reports, sketches, permit messages and the list of what stays or goes. If demolition reveals something new, compare it with that record. Get the right design answer before work continues.

These records also help a future owner understand what remains behind the finishes.