Pierce County, WA Environmental Rules: Defensible Space (2026)

R exempts Wildfire Defensible Space Activities from Title 18E's regular critical area permitting when they take place within 30 feet of existing dwellings, outbuildings, barns and commercial-use buildings, even where that 30-foot zone falls inside a critical area or its buffer. 070 Appendix F if shrubs are present beneath the tree; interruption of continuous shrub vegetation through selective thinning under the Appendix F guidelines; and replacement of evergreen species with less flammable native species, also per Appendix F. Appendix F's Brush Thinning Guidelines set spacing by slope: on 0-20% slopes, shrubs should be thinned to twice the height of the brush (a 3-foot shrub thinned to 6 feet apart), on 21-40% slopes to four times the height, and on slopes over 41% to six times the height.

Its Ladder Fuel Separation Guidelines call for vertical separation between shrubs and tree limbs equal to three times the shrub height, for example limbing a tree up to 18 feet above 6-foot shrubs. Appendix F also lists fire-resistant native trees, shrubs and ferns for replacement planting, such as Acer macrophylum, Arctostaphylos uva-ursi and Polystichum munitum. 020.