Can I build a DADU under Washington HB 1337 in Seattle?
Answered by AskBaily Editorial · Updated
Short answer
Yes. HB 1337 (2023, effective 2024) preempted most of Seattle's DADU and AADU restrictions on single-family lots — you can now add a DADU (detached accessory dwelling unit) on most SF parcels without the previous lot-size, coverage, or off-street-parking constraints. Typical Seattle DADU costs: $180K-$400K; permit timeline under HB 1337 streamlining: 4-10 months.
In detail
Yes. HB 1337 (2023, effective 2024) preempted most of Seattle's DADU and AADU restrictions on single-family lots — you can now add a DADU (detached accessory dwelling unit) on most SF parcels without the previous lot-size, coverage, or off-street-parking constraints. Typical Seattle DADU costs: $180K-$400K; permit timeline under HB 1337 streamlining: 4-10 months.
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