Chapter 18.115
FUEL MODIFICATION AREAS AND DEVELOPMENT STANDARDS FOR WILDFIRE LANDS
Sections:
18.115.020 Fuel modification areas.
18.115.030 Other wildfire protection standards.
18.115.010 Purpose.
The purpose of this chapter is to provide supplementary development regulations to reduce or minimize the potential impacts of wildfire on properties, the occupants of properties, and the occupants of adjacent properties. These standards function to balance the need to preserve natural habitat, to provide for aesthetic and functional landscaping, and to facilitate access to manmade structures by firefighters in the event of a wildfire. [Ord. 1192 § 1 (Exh. A), 2022.]
18.115.020 Fuel modification areas.
A. Applicability. A “fuel modification area” is defined as an area, either natural or manmade, where material capable of allowing a fire to spread unchecked has been treated, cleared or modified to slow the rate and intensity of an advancing wildfire and to create an area for fire suppression operations. Establishment of a fuel modification area does not involve stripping the ground of all native vegetation. A fuel modification area shall be required for the following construction:
1. All new buildings located on a vacant lot, that increase lot coverage by 200 square feet or greater, shall have a general fuel modification area covering the full extent of the property.
2. Decks, additions to existing buildings, and detached accessory structures which increase lot coverage by 200 square feet or greater, shall have a general fuel modification area extending 30 feet from the furthest extent of the addition, deck, or accessory structure, or to the property line, whichever is less.
B. General Fuel Modification Area Standards. To reduce fire spread both from and to structures on the property, and to adjoining properties, the establishment and maintenance of a fuel modification area requires the following:
1. All standing dead and dying vegetation shall be removed from the property.
2. Newly planted vegetation within 30 feet of any building, addition, or deck shall not include species listed on the city’s prohibited flammable plant list. This setback distance shall be increased by 10 feet for each 10 percent increase in the average slope of the property over 10 percent.
3. Within five feet of a building, addition or deck, existing vegetation listed on the city’s prohibited flammable plant list shall be removed, with the exceptions of significant trees as defined in RMC 18.20.020.
4. Within five feet of a building, addition, or deck, combustible manmade and natural materials are prohibited, including but not limited to bark mulch, stored wood, and accumulation of dry leaves and needles, except when permitted as follows:
a. Combustible materials may be permitted within five feet of a structure when the fire code official has determined the portion of the structure adjoining the combustible material is constructed with ignition-resistant building materials sufficient to reduce the spread of fire from the combustible materials.
5. Existing trees which are identified on the city’s prohibited flammable plant list shall be maintained to provide a clearance from new structures and additions, as follows:
a. Ten feet horizontal clearance from a chimney outlet. At no time shall tree crowns or limbs extend into the vertical plane of a chimney outlet.
b. Ten feet above the roof of a new building or addition.
c. Ten feet from the furthest extension of a new building or addition or deck.
d. In circumstances where pruning a tree to meet the clearance requirements of this subsection would compromise the health and survival of existing trees, the city may modify those requirements, but at a minimum the trees shall be pruned to maintain a ground clearance consistent with subsection (B)(8) of this section.
6. Canopy spacing of the outermost limbs of trees on the city’s prohibited flammable plant list shall be separated by at least 10 feet at mature size.
a. Groups of trees in immediate proximity to each other may be considered as one tree canopy when approved by the fire code official.
b. Canopy spacing requirements do not apply to significant trees, as defined in RMC 18.20.020, or trees that are not listed on the city’s prohibited flammable plant list.
7. Fire-resistant trees, those not listed on the city’s prohibited flammable plant list, shall be maintained to provide clearance from structures as follows:
a. Ten feet horizontal clearance from a chimney outlet. At no time shall tree crowns or limbs extend into the vertical plane of a chimney outlet.
b. Tree limbs shall be pruned to ensure they do not touch any part of a structure including but not limited to roofs, eaves, and decks.
8. Existing trees which are identified on the city’s prohibited flammable plant list shall be pruned to provide a ground clearance of a minimum eight feet above the ground, or one-third of the tree height, whichever is less.
9. Existing shrubs which are identified on the city’s prohibited flammable plant list shall be maintained to provide a clearance from new structures and other flammable vegetation as follows:
a. Five feet clearance from the furthest extension of a new building, addition, or deck.
b. Separation from other listed flammable shrubs within the general fuel modification area shall be a minimum of two times the shrub’s height at maturity.
10. Newly planted shrubs which are identified on the city’s prohibited flammable plant list shall be:
a. A minimum of 30 feet from the furthest extension of any building, addition or deck.
b. Separated from other listed flammable shrubs by a minimum of two times the shrub’s height at maturity.
c. Located outside of the drip line of a tree which is listed on the city’s prohibited flammable plant list.
11. The vertical clearance between the top of understory vegetation within the drip line of a tree and the lowest tree limbs shall be at least three times the height of vegetation where either the tree or vegetation is listed on the city’s prohibited flammable plant list.
12. Where necessary for erosion control, slope stability, riparian and wetland preservation and enhancement, performing functions considered beneficial in water resource protection, or aesthetic purposes, existing vegetation may be allowed to be retained consistent with an approved fire prevention and control plan, or upon written approval of the fire code official.
C. Modifications. The general fuel modification area standards may be reduced or waived when approved by the fire code official, provided it is demonstrated that the fire risk has been reasonably reduced such as in cases where ignition-resistant materials and construction methods, or vegetation type and separation, function to enhance the structure’s protection from exterior wildfire exposure. [Ord. 1192 § 1 (Exh. A), 2022.]
18.115.030 Other wildfire protection standards.
A. Roofing. Where 50 percent or more of a structure’s roof area is replaced within a five-year period, the roof covering shall be constructed or reroofed with materials in accordance with IR 2 under the International Wildland Urban Interface Code, as adopted by the city of Roslyn.
B. Fencing. Where fencing is attached to a building or deck, the fencing shall be made of noncombustible materials within five feet of the connection to the structure in compliance with the requirements in RMC 18.50.070(K).
C. Lawn Maintenance. All lawns shall be maintained at a height not to exceed six inches.
D. Compost Piles. Compost piles shall not be located adjacent to any building, addition, or deck. [Ord. 1192 § 1 (Exh. A), 2022.]