Home Additions & ADUs — Snohomish County
Home Additions & ADUsin Lynnwood.
Lynnwood's big rambler lots and a light rail station in the middle of them make the ADU math simple. The garage is usually the first candidate.
( Lynnwood )
Home Additions & ADUs for Lynnwood homes
Lynnwood was built out in the 1960s through the 1980s on generous lots, and a lot of those houses carry a two-car garage that nobody parks in. Converting it is the cheapest ADU square footage in the city: the slab, the walls and the roof exist, so the work is insulation, a raised and insulated floor, a kitchen, a bath, fire separation and an exterior door and windows that make it read as a home rather than a garage with a bed in it. Detached units are the next step on the larger parcels, especially within walking distance of the Lynnwood City Center station, where the rental return is strongest.
Permits run through City of Lynnwood Development & Business Services, which has adopted the state's ADU rules and is quicker than Seattle. The site questions we settle first are the same ones that decide the budget everywhere: where the sewer runs, whether the electrical service can carry a second kitchen, and how a crew reaches the back yard.
Permits for Lynnwood projects run through City of Lynnwood Development & Business Services, and we handle the filing and inspections as part of the job. For the full picture on how we approach this work, see our home additions & adus page — and for everything we build locally, our Lynnwood contractor page.
Typical Lynnwood investment
Broad ranges for orientation — your written estimate is free and itemized.
| Tier | Range | What it covers |
|---|---|---|
| Garage conversion | $40k–$150k | Living space at the low end; full ADU with kitchen, bath and entrance at the high end. |
| Ground-level addition | $250–$450/sq ft | Foundation, framing, envelope, systems and finishes, tied into the existing house. |
| Second story / detached ADU | $350–$550/sq ft | Structural work below, or a standalone unit with its own foundation and utilities. |
Lynnwood questions
- Can I convert my Lynnwood garage into an ADU?
- Usually yes, and it is the most cost-effective ADU on most Lynnwood lots. The conversion needs a permit, an insulated and raised floor over the slab, fire separation from the house if attached, a kitchen and bath, and windows and a door sized for a dwelling. Losing the covered parking is the trade-off.
- What does an ADU cost in Lynnwood?
- Garage conversions in Lynnwood typically run $60,000 to $150,000 in 2026 depending on whether it becomes a full unit with its own kitchen and bath. Detached units run $250,000 to $400,000. Both include design, permits and utility work in our estimates.
- Does being near the light rail station change the ADU rules?
- The ADU rules themselves follow state law citywide, but Lynnwood's zoning near the City Center station is more generous in some respects, and demand for rental units there is the highest in the city. We check your parcel's zone and what it allows at the free estimate.
- How long does an ADU take in Lynnwood?
- Permit review is typically weeks to a couple of months, faster than Seattle. Construction is eight to twelve weeks for a garage conversion and four to six months for a detached unit once the permit is issued.
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