Fire-Safe Landscaping Can Save Buildings And Properties From Flames

According to the California Department of Forestry and Fire Protection (CDF), Sacramento, Calif., fire-safe landscaping means strategically placing fire-resistant, drought-tolerant plants around the perimeter of a building and property. These plants can help resist the spread of fire to a building.

DEFENSIBLE SPACES. The California Fire Safe Council, Sacramento, Calif., said a primary consideration in fire-safe landscaping is to create a defensible space around a building, which means clearing all dry grass, brush and dead leaves from at least 30 feet from a building and at least 150 feet if the building is located on a hill or windswept area (see the image below right). Aspects of a defensible space include keeping trees furthest from the building, shrubs closer - yet still away from the building - and bedding plants and lawns closest to the building.

The Ministry Of Forests, Victoria, British Columbia, Canada, considers two zones in planning fire-safe landscaping - Zone One: moist and trim and Zone Two: high and clean. Zone One, or the area within 30 feet of a structure, should have limited trees and brush. The organization recommends low-growing, fire resistant plants, turf, ground covers, perennials and watered annuals in this area. Any individual shrubs and trees in Zone One should be at least 10 feet from a building. Zone Two, or the area up to 100 feet away from a structure, should have the trees and brush thinned out, according to the Ministry Of Forests. Therefore, pruning and removing overgrowth every three to five years is necessary.

The Ministry Of Forests also said following these guidelines interrupts a fire path and reduces the following fire fuels:

• Ground Fuels - all combustible materials between the ground and the ladder fuels, such as twigs, leaves, dry or cured grasses, shrubs, etc.;
• Ladder Fuels - fuels that provide vertical continuity between the ground and the tree canopy that will allow a fire to move up into the tops of trees, where a fire is harder to control; and
• Crown Fuels - the standing and supported forest fuels not in contact with the ground, such as branches, leaning deadfall, leaves, needles and cones.

PLANT SPACING. Because fire needs fuel to burn, the Fire Safe Council recommends that contractors avoid a continuous sequence of vegetation that can carry flames from the landscape to a building. The council said grouping plants of similar height and water requirements both slows the spread of fire and makes watering more efficient.

Contractors should space trees at least 10 feet apart and keep branches trimmed at least 10 feet from a roof, according to the Fire Safe Council. For trees taller than 18 feet, lower branches should be pruned within 6 feet of the ground.

PLANT MATERIAL. Installing fire-resistant, drought-tolerant plants that have a high-moisture content will reduce the threat of fire spreading quickly, said the Fire Safe Council. Because these plants require less water, the council noted the energy-saving benefit for using them in drought-stricken areas.

The Ministry Of Forests suggested selecting fire retardant plants with:

• Little or no seasonal accumulation of dead vegetation;
• Open, loose branching habits;
• Non-resinous woody material (for example, avoid conifers);
• Low volume of total vegetation;
• High moisture content in leaves;
• Drought tolerance; and
• Slow growth, requiring less frequent pruning.

WATERING. Proper watering is an important consideration because healthy plants burn less quickly. The Fire Safe Council said contractors should consider using drip irrigation for watering plants because it targets water directly to plant roots. Sprinklers can be used for turf areas to keep them fire resistant and healthy.

MAINTENANCE. Removal of dead branches, leaves and pine needles from a client’s yard - even from under plants - is the first step to reducing fire fuel around a building. The Fire Safe Council also recommended that contractors prune and thin shrubs, trees and other plants to minimize fuel.