Defensible space and fire mitigation in Sun Valley, NV

Sun Valley fills a narrow valley north of Reno at about 4,720 feet. About half of its homes are manufactured homes (American Community Survey), set on lots with hills of sagebrush on either side.

At a glance

• About 84% of buildings indirectly exposed, about 16% directly
• Risk to homes higher than 97.7% of US communities
• About half of homes are manufactured homes
• Reservoir Fire (1999, 6,163 acres) centred about 3.7 miles away

What is the ember problem in Sun Valley?

Indirect exposure, in the Forest Service's terms, means a building can be ignited by embers or by another building burning close by. Embers travel ahead of a fire and collect where wind drops them: against a wall, in the angle of steps, under a deck, in a pile of dry leaves.

The answer is a clean 5-foot zone. The Living With Fire guide lists what to remove from it: woodpiles, wood mulch, junipers, sage, dead leaves, pine needles and weeds.

What vegetation work helps a manufactured home?

The same work that helps any home, with attention to the base. Weeds and shrubs growing against skirting, vines on a porch and leaves blown under steps are all in the 5-foot zone. We cut, pull and haul the vegetation. Skirting, vents and decks themselves are the owner's or the park's to maintain.

• Shrubs and weeds removed along the base of the home
• Tree limbs pruned back from the roof and from any flue
• Dead trees and dead limbs removed
• Debris chipped and hauled off the lot

Old trees on small lots

About a third of Sun Valley's homes were in place before 1980, and the median dates from 1990. A shade tree planted beside a home 40 years ago can now cover the whole roof. Pruning it for clearance and taking out its dead wood is fire work and storm work at once. For how we approach that, see tree trimming in Sun Valley. Where a tree is dead, removal in a tight space is covered in removing a tree in a tight backyard.

The hills on both sides

About 16% of buildings are rated directly exposed, and those are the lots along the valley's edges where sagebrush meets the yard. There the work extends outward: brush thinned into clumps, grass cut and dead material removed out to 100 feet or the property line.

Fire perimeters mapped by the National Interagency Fire Center within about 10 miles include Reservoir in 1999 (6,163 acres, centred about 3.7 miles away), Poeville Road in 2020 (2,973 acres, about 5.6 miles) and Prater in 2017 (2,700 acres, about 6.9 miles).

Climate in one line

The Reno WFO weather station, about 2.2 miles from the centre of Sun Valley, averages 8.09 inches of precipitation a year (NOAA 1991-2020 normals). Unwatered plants are dry for most of the warm season.