Washington State Representative Brian Blake is sponsoring House Bill 1123, a micro housing bill. “We’re just trying to create some flexibility so folks who may want to build smaller structures that are more energy efficient are able to,” Blake said.

The bill would prevent counties and cities with fewer than 125,000 people from setting minimum dimensions for single-family home — unless needed for fire and safety.

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House Bill 1123, State of Washington

Update 11/04/2015: the bill is “retained in present status” (=not yet passed) and the house is in recess: https://legiscan.com/WA/bill/HB1123/2015 

Update 02/26/2016: This bill has been placed in the “X file” — it is no longer eligible for consideration and has been removed from calendars and the status sheet: http://apps.leg.wa.gov/billinfo/summary.aspx?bill=1123