Are two-story DADUs allowed in Seattle?

Yes — up to 18 ft (with a roof gable bonus to ~24 ft) on most NR2/NR3 lots. Height is the usual constraint, not story count.

What can the compare tool tell me?

Side-by-side comparison of two cities (or two scenarios) across the metrics that drive ADU economics: permit timeline, all-in cost band, median rent, gross yield, cap rate, tax reassessment impact, sewer/water connection fee, and HOA prevalence. Output is a structured table with sources cited for every number — useful for a homeowner deciding between two properties or two cities to invest in.

Can I compare different ADU sizes in the same city?

Yes — toggle to "size compare" mode and the tool runs a 500 sq ft, 750 sq ft, and 1,000 sq ft scenario in your chosen city. Outputs per-sq-ft cost (which favors larger), total dollar cost (which favors smaller), and net yield (which usually peaks around 750 sq ft for one-bedroom configurations in the Puget Sound).

Refreshed quarterly from our closed-contract database, county assessor levy schedules, and rental data from CoStar/Zillow ZORI/RentCafe. The last-updated stamp at the bottom of every compare table shows the exact refresh date. For pricing-critical decisions, always re-verify with a free 20-minute call — markets move.

Can I export the comparison?

Yes — PDF and CSV. The PDF includes a single-page summary, the full data table, and sources. It is suitable for a lender conversation or a partner discussion without further editing. The CSV is useful if you want to drop the numbers into your own Google Sheet or pro-forma.

Does it account for school district?

Optional layer — if you toggle "school weight," we annotate each city with the dominant school district and rough enrollment trend. We do not score districts (subjective), but we link to OSPI report cards so you can pull the metrics that matter to your household.

Can I compare more than two cities?

The web tool defaults to 2-up for readability on mobile. For 3-city or 4-city comparisons, generate a PDF for each pair and overlay — or just ask us and we will send a custom 4-up sheet by email within a business day. Sometimes a human-touch comparison is faster than a wider tool.

DATA_INDEX / COMPARISONS

ADU comparisons by city

One row per city × comparison. Pick yours.

Detached ADU vs. Garage Conversion

A new DADU buys you maximum size, rent, and resale value. A garage conversion buys you speed and a lower out-of-pocket. Which wins depends on your lot and your timeline.

DADU vs. Basement Conversion

Building down is cheaper but more constrained. Building out gives you rentable, financeable square footage with its own address.

Detached ADU vs. Attached ADU

Same code chapter, different economics. AADUs are cheaper but share walls. DADUs cost more but rent and resell as standalone units.

ADU vs. Home Addition

An addition grows your house. An ADU creates a second, rentable, financeable, salable dwelling. Different tools for different goals.

Prefab ADU vs. Stick-Built ADU

Prefab promises speed; stick-built delivers fit. In the Puget Sound, lot conditions and permit review usually erase the prefab time savings.

One-Story DADU vs. Two-Story DADU

One-story is simpler and ages with you. Two-story doubles your sqft on the same footprint — critical on small Seattle lots.

FAQ

Compare cities — frequently asked

What can the compare tool tell me?
Side-by-side comparison of two cities (or two scenarios) across the metrics that drive ADU economics: permit timeline, all-in cost band, median rent, gross yield, cap rate, tax reassessment impact, sewer/water connection fee, and HOA prevalence. Output is a structured table with sources cited for every number — useful for a homeowner deciding between two properties or two cities to invest in.
Can I compare different ADU sizes in the same city?
Yes — toggle to "size compare" mode and the tool runs a 500 sq ft, 750 sq ft, and 1,000 sq ft scenario in your chosen city. Outputs per-sq-ft cost (which favors larger), total dollar cost (which favors smaller), and net yield (which usually peaks around 750 sq ft for one-bedroom configurations in the Puget Sound).
Is the data live?
Refreshed quarterly from our closed-contract database, county assessor levy schedules, and rental data from CoStar/Zillow ZORI/RentCafe. The last-updated stamp at the bottom of every compare table shows the exact refresh date. For pricing-critical decisions, always re-verify with a free 20-minute call — markets move.
Can I export the comparison?
Yes — PDF and CSV. The PDF includes a single-page summary, the full data table, and sources. It is suitable for a lender conversation or a partner discussion without further editing. The CSV is useful if you want to drop the numbers into your own Google Sheet or pro-forma.
Does it account for school district?
Optional layer — if you toggle "school weight," we annotate each city with the dominant school district and rough enrollment trend. We do not score districts (subjective), but we link to OSPI report cards so you can pull the metrics that matter to your household.
Can I compare more than two cities?
The web tool defaults to 2-up for readability on mobile. For 3-city or 4-city comparisons, generate a PDF for each pair and overlay — or just ask us and we will send a custom 4-up sheet by email within a business day. Sometimes a human-touch comparison is faster than a wider tool.