WashingtonHB 11832025-2026 Regular SessionHouse

Concerning building code and development regulation reform.

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Bill Overview

Analyzed Economic Effects

7 provisions identified: 6 benefits, 1 costs, 0 mixed.

Fewer barriers to converting buildings into homes

Beginning July 27, 2025, Washington cities and code cities must ease housing additions in qualifying commercial- or mixed-use-zoned buildings. Buildings must have an occupancy certificate issued at least three years before the permit application. Where zoning allows multifamily housing, cities must allow up to 50% more units than zoning normally permits. Those units must fit entirely within the existing building’s outer structure and meet health and safety standards. Cities cannot require new off-street parking for added units, though they may require existing parking to remain. They cannot add special discretionary residential permits, except for emergency or transitional housing, or impose stricter-than-usual residential design rules. Extra exterior-design demands are limited to health, safety, and historic-preservation grounds, including protections for landmarks and historic districts. Cities cannot block units in covered building areas, except protected ground-floor commercial space along major pedestrian corridors. Adding units alone cannot trigger current energy-code upgrades for unchanged areas, transportation concurrency studies, or environmental studies. Permit denials based on existing rule violations require written findings of significant, measurable, and demonstrable public harm. Cities must update ordinances within six months after their next comprehensive plan update; conflicting local rules then become invalid.

More roof space for home solar

Beginning July 27, 2025, Washington cities and counties planning under the Growth Management Act must allow extra roof height for solar. Buildings may exceed local roof-height limits by at least 48 inches for roof-mounted systems using direct sunlight. Covered systems include solar electricity, heating, cooling, hot water, and industrial uses. State building codes still apply, and the rule does not require setback reductions beyond 36 inches. Local rules must be updated by the earlier of six months after the next comprehensive plan update or implementation progress report.

More room for energy-saving home insulation

Beginning July 27, 2025, Washington cities and counties planning under the Growth Management Act must allow more insulation space. The rules cover existing buildings retrofitted for housing and new or retrofitted passive-house projects. Existing buildings must have an occupancy certificate issued at least three years before the permit application. Passive-house projects must meet certification criteria from Phius or the International Passive House Institute. Wall insulation may extend up to 8 inches into required setbacks, and roofs may exceed height limits by 8 inches for insulation. Floor area is measured from the inside face of exterior walls, including drywall. Passive-house setbacks are measured from the foundation’s outside face; retrofit allowances also cover buildings already outside setback rules. The allowances cannot require less than 36 inches between homes, and state building codes still apply. Local rules must be updated by the earlier of six months after the next comprehensive plan update or implementation progress report.

Fewer design demands for qualifying housing

Beginning July 27, 2025, Washington cities and counties planning under the Growth Management Act cannot require two specific building-design features. They cannot require stepped or recessed exterior walls, or upper floors set farther back, for covered projects. These include affordable housing, passive-house construction and retrofits, housing conversions, modular construction, and mass timber construction. Other permit and building-code requirements remain. Local rules must be updated by the earlier of six months after the next comprehensive plan update or implementation progress report.

Fewer required parking spaces for housing

Beginning July 27, 2025, Washington cities and counties planning under the Growth Management Act generally cannot require off-street parking for listed projects. These include affordable housing, passive-house construction and retrofits, modular construction, and mass timber construction. A safety exception requires Commerce to certify findings from an empirical study by a credentialed transportation or land-use expert. The study must show that removing required parking makes conditions significantly less safe; Commerce provides study guidance. Counties may also require parking where county roads do not meet standards adopted by cities in that county. Separate transit-related limits cover housing built after July 1, 2019, in Growth Management Act jurisdictions. Qualifying transit is within one-quarter mile and runs at least four times hourly for at least 12 hours daily. Nearby senior and disability housing has no resident parking minimum, but staff and visitor parking may be required. Where on-street parking is infeasible, one or more spaces per bedroom may be required; occupancy restrictions may also be required. For nearby market-rate multifamily housing, parking minimums cannot exceed one space per bedroom or 0.75 space per unit. Higher minimums require findings of inadequate on-street capacity or physical barriers. Local adoption of the listed-project exemption is due by the earlier of six months after the next comprehensive plan update or implementation progress report.

Smaller affordable homes meet local size rules

Beginning July 27, 2025, Washington cities and counties cannot require covered affordable homes to exceed specified sizes. For low-income and very-low-income households, the thresholds are 400 square feet for studios and 550 for one-bedroom homes. They are 750 square feet for two-bedroom homes and 1,000 for three-bedroom homes. These limits cap local size demands, not the size builders may choose to provide. If the project’s average unit is smaller, localities must allow affordable units comparable in size to its market-rate units. Low-income housing built under affordable housing incentive programs is exempt, and co-living housing follows separate state rules. Local rules must be updated by the earlier of six months after the next comprehensive plan update or implementation progress report.

Older affordable housing parking caps removed

Beginning July 27, 2025, the law removes an older statewide parking cap for very-low-income and extremely-low-income housing. It covered homes within one-quarter mile of transit running at least twice hourly for at least 12 hours daily. The former cap was one parking space per bedroom or 0.75 space per unit, subject to exceptions. Local governments are no longer bound by that cap, but the repeal does not override the separate exemption for qualifying affordable projects.

Sponsors & Cosponsors

Sponsor

Davina Duerr
Democratic • House

Cosponsors

April Berg
Democratic • House
Beth Doglio
Democratic • House
Cindy Ryu
Democratic • House
Jamila Taylor
Democratic • House
Joe Fitzgibbon
Democratic • House
Julia Reed
Democratic • House
Lauren Davis
Democratic • House
Lisa Parshley
Democratic • House
Liz Berry
Democratic • House
Mari Leavitt
Democratic • House

Roll Call Votes

All Roll Calls

Yes: 84 • No: 60

Senate vote • 4/14/2025

3rd Reading & Final Passage

Yes: 28 • No: 21

House vote • 3/11/2025