MBAKS joined Governor Ferguson as he signed HB 1096 into law.

Big news for housing in Washington: Governor Bob Ferguson has signed HB 1096 into law, legalizing residential lot splitting across the state. After three years of advocacy, this landmark reform creates a straightforward, administrative process for homeowners and homebuilders to divide a single lot into two—unlocking small-scale infill, expanding homeownership, and creating new paths to affordability.

For decades, Washington law required homeowners and builders to navigate complex, costly subdivision processes that could take years—even when the existing lot already met zoning and infrastructure standards. HB 1096 finally fixes that, allowing qualifying lots to be split without major red tape, and enabling cities to review building permits alongside lot split applications.

Lot splitting won’t just create more homes—it will also allow aging homeowners to age in place, help families build wealth through multigenerational housing, increase opportunities for supplemental income, and offer first-time buyers access to starter homes in high-opportunity neighborhoods. It complements recent reforms like HB 1110 (middle housing) and supports the Growth Management Act’s goals by enabling gentle infill where it’s needed most.

HB 1096 ensures accountability by requiring clear, objective standards, displacement mitigation, and infrastructure availability before approval. Cities must implement the new policy by 2027 (or within two years for non-GMA jurisdictions), and guidance is expected from the state Department of Commerce later this year.

This is a major step toward restoring affordability and giving everyday Washingtonians more options to stay, build, and invest in their communities—one lot at a time.

View MBAKS Lot Splitting Brief for more information: Creating More Housing Through Lot Splitting.

By Mike Pattison, Snohomish County Manager

In December 2016, the Washington state Supreme Court struck a blow to vesting rights when it ruled that newly adopted stormwater regulations do not vest. The Court let stand a window for certain projects to remain vested. The new stormwater regulations will apply to all applications submitted after July 1, 2015 and projects approved prior to July 1, 2015 which have not started construction by June 30, 2020.

The case, Snohomish County, et al. v. Pollution Control Hearings Board, will severely impact applications that have been submitted to a jurisdiction but are not yet approved. The opinion eliminates vesting for environmental regulations mandated by the state, including stormwater.

An editorial by MBA President Mike Walsh was recently published in The Herald discussing the case and explaining why vesting is so important to the homebuilding industry.

While there is no ability for local government to overcome the decision with local legislation, King and Snohomish counties are currently petitioning the Court to reconsider and clarify some of the opinion.

Further, there is a proposal before the Washington State Legislature, Senate Bill 5212, that would restore vesting rights.

For more information, contact Snohomish County Manager Mike Pattison, 425.460.8203.

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