Insights
from the field.
Washington HB 1337, in plain English
What the 2023 statewide ADU law actually requires of cities — and what it means if you own a single-family lot in the Puget Sound.
Read article →How our Seattle ADU costs compare to AARP's national data
AARP's ADU research is the most-cited benchmark in the country. Here is how Puget Sound numbers stack up.
Read article →Seattle's ADU code, decoded
SDCI Tip 116 plus SMC 23.44.041 in one read — height, setbacks, FAR, and the rules most homeowners get wrong.
Read article →Seattle ADU rental comps in 2025
Census ACS, Zillow Research, and our own lease ledger — what a 700 sq ft DADU actually rents for in Seattle today.
Read article →Financing an ADU: 203(k), HomeStyle, HELOC, cash-out
Four mortgage products and the lot conditions that make each one the right answer.
Read article →IRC Appendix AQ — when 'tiny' is the right answer for an ADU
ICC's tiny-home appendix sets the rules for sub-400 sq ft units. Here's where it actually fits in Seattle and the Eastside.
Read article →When Seattle dropped ADU owner-occupancy — and why it changed the math
The 2019 reform that quietly transformed Seattle into one of the most ADU-friendly cities in the United States.
Read article →What an ADU does to your property tax in King County
King County Assessor data, applied to a real Seattle parcel — the assessed-value bump and the tax math.
Read article →Bellevue ADU rules — what changed under HB 1337
Bellevue updated LUC 20.20.120 to comply with state law. Here is what's actually different on the ground.
Read article →Multigenerational ADUs in the Pacific Northwest
Pew + Generations United data, plus what we have learned designing for three generations under one address.
Read article →Kirkland ADU rules — the most predictable Eastside permit path
Kirkland Zoning Code Chapter 115 plus the City's pre-application process produce the shortest median permit timeline on the Eastside.
Read article →Passive House for a Puget Sound ADU — does it pencil?
PHIUS-certified envelope, solar-ready roof, NEEA incentives. A real cost-benefit analysis from our last two PH projects.
Read article →What an ADU really costs in Seattle in 2025
Honest, line-by-line numbers from our last twelve completed DADUs — design, permitting, hard costs, and the line items most contractors hide.
Read article →Seattle's Pre-Approved DADU plans — when they make sense
A free SDCI program that cuts permit time in half. Here's when to use it and when to walk away.
Read article →Septic or sewer? What it means for your ADU
Public Health — Seattle & King County governs on-site sewage. Here's what changes when you add a second unit on septic.
Read article →DADU or AADU? How to choose for your lot
Detached cottage or carved-out unit inside the home — the right answer depends on your lot, your goals, and your willingness to share a wall.
Read article →Long-term vs. short-term rental ADU in Seattle
Seattle FAS short-term rental rules, the math vs. long-term tenancy, and what we see actually working.
Read article →The 2021 Washington Energy Code, applied to ADUs
WA Energy Code 2021 is one of the most aggressive in the United States. Here's what it actually requires of a new DADU.
Read article →Designing an aging-in-place ADU
AARP Livable Communities + ADA standards, applied to a real Seattle DADU built for an owner's parents.
Read article →Detailing an ADU for Pacific Northwest rain
Building Science Corp + ASHRAE 160, applied to the wall, roof, and window details that fail in our climate.
Read article →Building an ADU for aging parents
AARP Public Policy Institute documents the caregiving wave. Here is what an ADU costs vs. assisted living, and what to design in.
Read article →Real ADU permit timelines across the Puget Sound
Our actual submission-to-issuance data for Seattle, Bellevue, Kirkland, Redmond, and Tacoma — what to expect and where projects stall.
Read article →Materials that age well in the Pacific Northwest
Our material palette after a decade of building in Seattle weather: what we still spec, what we stopped specifying, and why.
Read article →