Lake County FEMA Metal Roof Project:
Defensible Space Specifications
Goal: Remove Understory Hazardous Fuels within the 30 foot Defensible Space of Treated Structures.
Defensible Space is the area within 30 feet of all eligible structures on which a fire-resistant metal (or authorized
alternative) roof has been installed with FEMA Hazard Mitigation Assistance grant funding. If an outbuilding (or
propane tank) is within 30 feet of a primary structure, the defensible space extends to the area within 30 feet of
that outbuilding (or propane tank).
Understory Hazardous Fuels to Remove
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Dead standing trees (snags) less than 5" diameter at breast height (dbh) of 4 feet.
Live and dead balsam fir less than 5" dbh.
Limbs of mature conifer trees over 5” dbh that are within 6 feet of the ground or overhanging buildings.
Limbs of young conifer trees up to 1/2 of the tree's height.
Dead standing grass.
Understory Species to Leave
 Deciduous brush species (hazel, alder, maple, etc.) are not considered hazardous fuels, but may be cut and
mulched for operability purposes.
 If at all possible, leave all white spruce, white pine, red pine, tamarack, and cedar, particularly in areas
where these species are scarce. Similarly, avoid damaging these species. In some cases, dense young
groups of these species may need to be thinned to reduce fuel hazard and prevent mortality.
Hazardous Fuel Disposal
Removed understory hazardous fuels must be disposed of in one of two ways:
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Chipping and mulching on site. If at all possible, the chips and mulch should be placed outside of the
defensible space. Chips should be evenly distributed on the ground and not exceed 4" in height.
Piling and legally burning. Removed hazardous debris piles should be placed well outside of the defensible
space, and not beneath the canopies of residual trees. Piles should be burned in the winter when there is
more than 3 inches of snow or with a burning permit.
Minimize the amount of material placed beneath residual pine, spruce, tamarack, and cedar trees.
Selective Canopy Thinning
In some cases, densely spaced mature trees of white spruce, white pine, red pine, jack pine, tamarack, and cedar
may need to be thinned to reduce fuel hazard and prevent mortality. Ideally, mature conifer crowns should be
separated by 10-15 feet.
Areas to Avoid Treating
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Treat only upland areas. Treatment is not allowed in wetland areas.
Use only hand treatment (not heavy equipment) within 50 ft of a water body.1
Limit treatment to light thinning within 10 ft of a water body to maintain visual screening. 1
Other areas to avoid may include, but are not limited to, stream channels, rock outcrops, naturally wet
areas, and other sensitive areas.
To comply with Lake County Land Use Ordinance and Minnesota Shoreland Rules.