New Mercer Island Development Rules Now In Effect

MERCER ISLAND, WA - Now in effect: new city development standards that will cut down the size of houses built on the island. In September, the City Council passed new regulations that, among other rules, will create maximum house size limits for each residential zone.

The new regulations went into effect Nov. 1, and were produced after a year-long study by the Planning Commission and City Council. The new regulations apply only to new homes and remodels, and do not affect apartment developments.

Here are the new regulations, according to the Planning Commission:

NEW LIMITS ON HOUSE SIZE AND BULK

• Reducing allowed gross floor area from 45% to 40% of the lot
• Implementing a maximum house size for each residential zone
• Height limited to 30’ on downhill side (reduced from 35’)
• Side setback increased to 17% of lot width for lots wider than 90 ft, with additional increases for homes with a “tall wall”

• A minimum of 30% of large trees must be retained when a lot undergoes major construction
• Priority for retention of large, healthy trees
• Exceptional trees are provided additional protection, including requirements to re-design
• Tree removal on any lot will require a permit (exceptions for trees that are hazardous, very small or noxious/invasive)

• Up to 9% of the net lot area may be used for hardscape surfaces (decks, patios, etc.)

• Construction hours reduced to 7am-7pm on weekdays and 9am-6pm on Saturdays
• Require construction management plans and a construction schedule for larger projects and permit renewals
• Limit permit renewal and extensions to a total of 3 years

• Eliminate impervious surface and fence height deviations
• Toughen standards on all other variances and deviations

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