Encourages the development of affordable housing.

Finds that there is a large, unmet need for affordable housing in the cities and counties of Washington that is increasing every year.

Finds that many single-family residential neighborhoods were developed at an earlier time at densities less than the maximum allowable under current zoning regulations.

Finds that the growth management act requires increased densities in single-family areas, and that the rising costs of public facilities to accommodate growth coupled with insufficient revenues available for such facilities make infill housing within existing developed areas an economic necessity. The legislature concludes that allowing reasonable development of underutilized parcels of land within urban growth areas has significant potential to provide much-needed affordable ownership housing while also providing resources to existing property owners and their communities.

Declares that it is the purpose of this act to: (1) Increase the supply of affordable housing without government subsidies or the provision of additional public facilities;

(2) Encourage moderately priced for-sale housing in single-family neighborhoods and increase housing opportunities for people in a variety of life cycle stages; and

(3) Provide homeowners with an additional option for the portion of their property that is not required for the use of the existing residential unit.