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A Guide to Designing Zoning & Building Standards for Local Officials
Protecting Life and Property From Wildfire:
An Introduction to Designing Zoning & Building Standards For Local Officials
This Information was Developed by the Great Lakes Forest Fire CompactIntroduction
Firewise Landscaping Guidelines
Vehicular Access Guidelines
Guidelines For Signing
Guidelines for Emergency Water Supplies
Structural Design and Construction Guidelines
Guidelines for Controlling Open Burning
Understanding the Risks
In the Great Lakes region, there has been a large increase in the number of primary and second homes in rural areas. The number of rural homes has increased by over 50% during the 1980's. In some areas, over 1/2 of the homes are second, or vacation homes. This has placed a tremendous burden on local units of government, especially fire service agencies. With more people living in rural areas, their activities lead to more wildfires. For example, debris burning accounts for over 1/3 of the fire starts in Michigan. These fires, by their very nature, occur in close proximity to homes and other structures.
Understanding the Hazards
The natural vegetation of much of the Great Lakes region developed in response to fire. Fire is an integral part of the natural order. The vegetation in the region burns readily, especially during the early spring when most wildfires occur. Rural residences built surrounded by combustible vegetation become potential fuel for a wildfire.
The combination of rural residences and highly combustible vegetation has created a wildfire problem as potentially devastating as any in the nation. As a result, the damage caused by wildfires has steadily increases over the past two decades. Where once wildfires burned only natural resources, now homes and property are involved, and people's lives are endangered. Recent fires in the Great Lakes region have brought this lesson home with a vengeance. The Stephan Bridge Road Fire near Grayling, Michigan destroyed 76 homes in a little over four hours. Ontario's Kenora 14 fire threatened over 200 cottages, and burned 10 of them before it was extinguished. The Huntersville Fire in Minnesota burned several cabins and a store, and cost more than $1 million to suppress.
These fires have shown, among other things, that there is often little that fire fighters can do to protect property once a wildfire has begun. What makes the difference are the measures that have been put into place before the fire; fire safety measures can reduce the exposure of life, property, and resources to an "acceptable level of risk" and provide "defensible space" that can help protect residents and enable firefighting equipment and personnel to operate during a wildfire.
What Can be Done?
This guidebook has been provided to give you, the local official, a tool to help you put measures in place to reduce potential loss of life and property. These measures include enacting and enforcing fire safe building standards, construction of adequate road and water systems in rural developments, and land-use planning and zoning to guide development. It offers basic information and recommended fire safety standards so that land-use policies and zoning criteria can be developed to help reduce the possibilities of wildfire disaster. It should also be noted that different models for addressing wildfire hazards through zoning and building codes exist in other regions. Summit County, Colorado is one example where the building permit process has been used very effectively to address wildfire hazards.
Use of NFPA Standards
This document makes numerous references to various standards set by the National Fire Protection Association (NFPA). NFPA policy allows public authorities with lawmaking or rulemaking powers to use their standards in local ordinances. For further information contact: Secretary, Standards Council; National Fire Protection Association; P.O. Box 9101; 1 Batterymarch Park; Quincy, MA 02269-9101.
Recommendations For Protecting Property From Wildfire
These recommendations have been agreed upon for use within rural areas of the Great Lakes region of Michigan, Wisconsin, Minnesota, and Ontario.
Typically, a wildland/urban interface problem (or what we will call a fire-prone property problem) exists anywhere structures encroach into the wildlands. In such situations, an uncontrolled wildfire can spread from wildland vegetation to encroaching structures, or can spread from a structure to surrounding vegetation.
One of the most critical concepts in dealing with the wildland/urban interface problem is the concept of defensible space. Defensible space is an area around a structure in which vegetative fuels have been modified and/or reduced to show the spread of a wildfire. It provides the fire service with an opportunity to intervene in the fire prone property problem.
There are three benefits of defensible space:
Fire-wise landscapes provide defensible space, protect structures from approaching wildfire, and reduce the potential for a structure fire spreading to the wildland. Defensible space should initially be provided by the developer, and later, maintained by the homeowner. Coniferous trees, such as pines and spruce, create special hazards that should be addressed when providing defensible space around a structure(s).
Within 30 Feet (10 m) of All Structures:
This fuel break is the primary defensible space zone. Within this zone, steps should be taken to change the type of combustible vegetation present, reduce the amount of burnable vegetation, and/or eliminate highly hazardous coniferous vegetation.
Maintain an area free of combustible materials within 3 feet (1 m) of structures. This strip is the first section of your defensible space, and reduces the threat of a surface fire coming in direct contact with a structure. Within this area, use noncombustible landscaping materials, such as gravel, marble chips, concrete, or mineral soil.
Trees in this 30 ft (9 m) area should be pruned to a height of 6 to 10 feet (1 - 3 m). Space trees so that the edges of crowns are 10 to 16 feet (3 to 5 m) apart.
Keep this fuel break free of anything that could burn. Remove small trees, household debris, brush, and ground fuels, such as leaves, or pine needles. A green lawn or rock garden makes a good fuel break, but grass must be kept watered and cut, and dead grass must be removed. Stone, brick, or masonry walls also make good fuel breaks when they are free of vegetation. They can be located either inside or outside of the fuel break area.
Beyond the 30 Foot (10 m) Fuel Break Area:
Thin trees to provide 10 feet (3 m) of open space between the crowns of adjacent trees. Prune branches away from power lines. Also prune lower branches to 10 feet (3 m) above the ground. Remove small shrubs, scrub growth, ground litter, and dead trees.
Fire Resistant Plants:
Many common plants naturally resist fire, and are characterized by low oil content, leaves that stay moist, and low ground litter production. While all plants will burn if the conditions are severe enough, the following plants are adapted to the Great Lakes region, and have fire resistant characteristics:
Additional Slope Requirements:
Where slopes are sufficiently steep to increase the hazard, additional defensible space will be required on the down-slope side. For slopes over 15%, provide an additional 30 feet (10 m) of vegetative clearance.
Store items that could easily catch fire at least 30 ft. (9 m) from any structure, including wooden fences and outbuildings. They should be outside of the fire break. These items include firewood, heating oil and propane tanks, brush and slash, gasoline, and paint and solvents. Protect fuel and LPG tanks by clearing vegetation from around them for a distance of 10 feet (3 m). All fuel piping should be underground.
Get rid of brush and/or slash by chipping. Gasoline, paint, and solvents can be very dangerous. Store them in cool, well-aired area away from other combustible materials. Clean up spills and safely dispose of soiled rags.
All barns, storage buildings, pump houses, and similar structures that are within the 30 foot (9 m) fuel break should be separated by at least 10 feet (3 m) to reduce exposure.
All roads and streets should provide for safe simultaneous access for emergency equipment and civilian evacuation, giving unobstructed traffic circulation during an emergency. Where fuel breaks and greenbelts are required, the road system should provide access. All vehicular access and gates servicing such access should meet the specifications provided in this document. All roads should be designed and constructed according to standards published by the American Association of State Highway and Transportation Officials (Canadian Association of Transportation Officials in Ontario), but should also meet the minimum requirements set forth in this document.
Private Roads, Streets, and Driveways should meet NFPA 1141, Fire Protection for Planned Building Groups.
Specific Design Requirements:
All developments should have multiple access routes. Access routes should be designed to accommodate planned traffic flows and use looped road networks.
Road Easements and Rights-of-Way:
Easements and rights-of-way should be wide enough to accommodate the roadway, shoulder, vegetation modifications and other local requirements on or along roads or streets. Where necessary for compliance with this standard, easements should be obtained from adjacent property owners.
Roadways:All roads and streets should be graded and surfaced, and of sufficient design to support the weight of a 20-ton (18 tonne) vehicles. Roadways should be a minimum of 24 ft (7 m) wide, and should provide for simultaneous access for emergency vehicles and the evacuation of residents.
Grades should not be greater than 10%. Roadways should be designed to prevent pooling of water on the road surface.
All curves should have a minimum radius of 100' (30 m), measured at the center line.
There should be an improved gravel shoulder, with a minimum width of 4 ft. (1.2 m) on each side of the traveled surface.
Where parking will be allowed along the roadway, at least 9 ft (3 m) of improved width should be provided.
Dead-end roads should not exceed 600 ft (183 m) in length in areas of extreme hazard classification. They should not exceed 1000 ft (305 m) in other areas. All dead-end roads should have a turnaround at the closed end of at least 100 ft (30 m) in diameter. In areas of low wildfire hazard severity, hammerhead-T turnarounds may be used to provide 3-point turnaround capability.
All driveways should provide a minimum unobstructed width of 12 ft (4 m) and a minimum unobstructed height of 14 ft (4.2 m) every 400 ft (122 m) along the driveway's length. Driveways over 200 ft (61 m) long should provide a turnaround within 50 ft (15 m) of the building or structure.
All gates should provide a clear opening at least 2 ft (.6 m) wider than the roadway, and should be located at least 30 ft (9 m) from the public right-of-way. Gates should open inward, allowing a vehicle to stop without obstructing the public road.
All roads, streets and buildings should be designated by names or numbers on signs clearly visible and legible from the roadway to facilitate the locating of a fire and to avoid delays in response.
All public and private roads and streets should be identified by a name or number in a consistent system that provides for sequenced, or patterned, numbering and unique naming within each jurisdiction.
Street and road signs should be located at intersections. Signs should be readable from all directions of traffic flow for a distance of a least 100 ft (30 m), and should be mounted 6 to 8 ft (2 m) above the road surface. Signs should be in a horizontal orientation. Letters, numbers, and symbols should be at least 4 in. (10 cm) high, with a 1/2 in (12 mm) stroke, reflectorized, and of a contrasting color to the background.
Signs should be installed prior to final acceptance of road improvements.
All buildings should have a unique address and street number. Letters, numbers, and symbols used to indicate addresses should meet the same standards as street signs, except they need not be reflectorized.
Some provision should be made to provide water for fire suppression in rural areas. This section is provided to help evaluate emergency water supplies, and how they are designed, constructed, and maintained. It is especially intended to assist in evaluating emergency water supplies for rural developments of more than one housing unit.
Water should be available to provide a minimum fire flow of 250 gpm (946 1/min) for two hours.
Static water supplies should be designed and constructed to conform to NFPA 1231 Standard on Water Supplies for Suburban and Rural Fire Fighting.
Fire Agency Notification:
The appropriate authorities should be notified in writing before any water system is constructed or altered, and before site development or construction of any building takes place so that fire protection needs can be evaluated, and sufficient water supplies established.
Signing Water Supplies:
Each hydrant or access to water should be identified with a fire-resistant reflectorized sign with the words "Draft Water" or "Pressure Water." Signs should have letters at least 4 in (8 cm) high with a 1/2 inch (1 cm) stroke, reflectorized, and of contrasting color, and should be located near the water access.
All buildings in rural areas should be designed and constructed to comply with one of the model building codes with this standard.
Structures and developments in or adjacent to wildland fire hazard areas should be located, designed, and constructed to minimize the possibility of ignition from a wildfire and to minimize the spread of a structural fire to the wildland.
Roof coverings should meet at least NFPA class C standards. Subdivision covenants, conditions, and restrictions should not require the use of roof covering materials that do not meet NFPA Class C requirements.
All vents in roofs, gables, and eaves should be screened with corrosion-resistant, noncombustible wire mesh with openings no larger than 1/4 inch (6 mm) in size.
Overhangs and Stilt Construction:
Eaves, cantilever balconies, and other overhangs should be enclosed with 1/2 in. (13 mm) nominal sheathing, or the equivalent. Decks and other structures with stilt construction should have their undersides completely enclosed with 1/2 in (13 mm) nominal sheathing, or a equivalent material.
All windows and glazed openings within 30 ft (9 m) of concentrations of vegetative fuels should be provided with closable, solid, exterior shutters, especially in areas of highly hazardous fuels, such as pine or spruce.
Exterior walls should be constructed of at least 1/2 inch (13 mm) sheathing or an equivalent material. Exterior sheathing should extend from the roof line to ground level.
Chimneys and Flues:
All chimneys and flues should be provided with an approved spark arrestor made of 12-gauge welded or woven wire mesh with holes no larger than 1/2 inch (13 mm). A 10 foot (3 m) clearance should be maintained between all chimney or flue outlets and any obstruction or vegetation.
Manufactured homes should meet all applicable construction and safety standards, and should be provided with full skirting constructed of 1/2 in (1 cm) nominal sheathing or an equivalent material. All porches and sundecks should be constructed of fire-retardant materials, and should have their undersides enclosed with 1/2 in (13 mm) nominal sheathing or the equivalent.
Debris burning is one of the highest risk activities that occur in rural areas. Over 1/4 to 1/3 of all wildfires in the Great Lakes Region are started by this activity. Because of its very nature, debris burning typically takes place in close proximity to rural structures, placing them at great risk. Local units should strongly consider taking steps to address this risk.
Reducing the Risk of Debris Burning Fires:
There are many steps local units of government can take to reduce the risk of wildfire that debris burning poses. Many jurisdictions have eliminated the outside burning of debris entirely. There are alternative methods of disposing of these materials that do not involve the risk of wildfire:
Yard wastes such as leaves and needles can be plowed into garden areas to enrich the soil
Yard wastes can be composted
Brush can be chipped and used as a ground cover outside of the 30'(9 m) fuel break area.
Small to moderate amounts of leaves can be chopped with a lawn mower and allowed to decompose right on the lawn.
Another approach is to limit debris burning to certain types of materials during periods of low fire risk. For example, debris burning could be limited to brush and large woody material only, during those periods when the ground is snow-covered.
These guidelines provided courtesy of the Great Lakes Forest Fire Compact
Copyright © 2001-2013 State of Michigan