Wildfire Ready: Critical Prep to Protect Your Business

This zone is your second line of defense – extend protection to 30 feet in 3 focus areas: Vegetation Management, Propane Tanks, & Detached Structures to slow fire spread and reduce flame intensity near your building.  

1. Measure Your Zone 

• • Use a tape measure to mark the 5-30 foot perimeter around your building. Once marked, follow the steps below to manage vegetation, large items, and detached structures to eliminate connective fuels. Connective fuels are materials that provide a continuous pathway for a fire to spread to your home. 

2. Vegetation Management (Trees, Shrubs, Landscape) 

Tree Spacing 

• • 6-foot Vertical Clearance: Regularly maintain at least 6 feet of clearance between the ground and the lowest branches, or 1/3 of the tree’s total height if the tree is shorter than 18 feet. 

• • • Example: If a tree is 15 feet tall, 1/3 of its height is 5 feet, so prune lower branches to create at least 5 feet of clearance. 

• • 10-foot Horizontal Clearance: Maintain at least 5 feet of clearance between the building and any part of the tree, keep individual tree canopies 10 feet apart where there are multiple canopies, and ensure a minimum of 10 feet from buildings with chimneys or stovepipes.  

• • You may have clustered trees if the combined canopy width is trimmed to 10 feet or less. Treat the cluster as a single canopy when measuring.  

• • • Example: A group of three thin trees may be kept as a cluster if trimmed so their combined canopy spread is 10 feet or less. 

• • Create separation within continuous rows or large tree clusters exceeding 10 feet by trimming canopies or removing select trees to maintain the proper spacing. 

• • Safety tip: If branches or trees are near power lines, contact your utility provider to remove them. Never attempt this yourself. 

Shrub Spacing 

• • Plant Selection: Choose low-growing, native, fire-resistant plants, and space them based on their mature size. When ignited by wildfire, shorter plant heights help reduce flame length (which these flames bend in high winds), and adequate spacing slows fire spread.  

• • Foliage Diameter: Identify each shrub or cluster (treated as one shrub) you want to measure and space. Treat a group of shrubs growing close together as one cluster. Keep each shrub or cluster trimmed to 10 feet wide or less. 

• • Horizontal Spacing: is determined by shrub height. The standard spacing is 10 feet apart.   

• • • If you prefer, you can calculate a smaller horizontal spacing based on shrub height. Measure the height of the tallest plant, then multiply that height by 2 to determine the minimum spacing neighboring shrubs should be placed.  

• • • • Example: If the tallest shrub is 3 feet tall, multiply 3 × 2 = 6 feet. In this case, shrubs should be at least 6 feet apart.  

• • • • Tip: Shorter shrubs need less spacing, so keep shrubs trimmed lower to maintain smaller spacing. 

• • • If the shrubs are too close, trim or relocate them to create proper spacing. Create gaps within continuous hedges or privacy screens by removing plants as needed to maintain adequate distance between the remaining shrubs. 

• • Avoid Ladder Fuels: Relocate shrubs from beneath tree canopies to prevent fire from spreading upwards into the tree crown.

Landscape Maintenance 

• • Grass Height: Keep grass cut to less than 4 inches (or under 18 inches on slopes for erosion control).  

• • Remove Dead Vegetation: Routinely clear all dead or dying grass, weeds, plants, shrubs, trees, logs, stumps, branches, leaves, and pine needles.  

• • Firewood Storage: If your commercial building uses solid fuel appliances or equipment, store firewood and wood piles at least 30 feet from the building. 

3. Liquid Propane Gas (LPG) & Fuel Tanks 

• • Option 1: The tank is at least 30 feet from the building, if not, consult with your supplier to relocate the tank. 

• • Option 2: If Option 1 is not possible, place the tank at least 10 feet from the building and follow these guidelines: 

• • • From 0-10 feet around the tank: Remove all vegetation, groundcover, and combustible items (e.g., fences) and replace with low-maintenance noncombustible hardscape (e.g., gravel, pavers, river rock, DG, or concrete) or bare soil.  

• • • From 10-20 feet around the tank: Keep grass cut to less than 4 inches, remove plants, shrubs, small trees, and dead vegetation (e.g., limbs, logs, and stumps). Healthy, mature trees may remain but should be pruned to allow for a 6-foot vertical clearance above the tank. 

4. Detached Structures (10-30 Feet from the Building) 

Placement & Quantity 

• • Place detached accessory structures, such as garbage enclosures, freestanding pergolas, sheds, and storage units, at least 10 feet from the main building, including any attached features like accessibility ramps or patios, and from each other.  

• • • Exception: Fully noncombustible metal pergolas do not require spacing.  

• • Limit to three total structures within this zone. 

Roof Covering 

• • Freestanding Pergolas: Remove combustible roof slats (e.g., wood or vinyl) to ensure no more than 15% coverage of the total surface area.  

• • • Tip: For 2x boards (e.g., 2×4, 2×6 turned on the 2x edge), allow approximately 1-foot spacing between boards.  

• • Solid Roofs: Use Class A fire-rated roofing materials (e.g., metal, concrete/clay tile, slate, or asphalt shingles).  

• • Avoid combustible solid coverings such as wood, plastic corrugated panels, and fabric shades. Instead, consider using a retractable shade screen housed in a noncombustible material. 

Noncombustible Base Material & Zones 

• • Each structure must have its own 0–5 Foot Noncombustible Zone that does not overlap with others. 

• • Apply 6 vertical inches of noncombustible material at the base of each combustible structure and its posts. 

• • • Example – Elevated Storage Shed: Enclose the underside with noncombustible material (e.g., 1/8-inch metal mesh, stone, concrete blocks, or brick).  

Open Structures (e.g., Garages, Storage Sheds, or Loading Docks) 

• • Do not store combustible items inside (e.g., wooden pallets, cardboard, or plastic containers). Relocate these materials to enclosed areas inside the facility. 

• • If interior walls have exposed combustible materials (e.g., wood), the structure should be fully enclosed to reduce ignition risk. 

• • Loading dock example: An open dock with stacked wooden pallets outside would be high risk. Moving those pallets just inside the doors provides protection without disrupting operations. 

Around the Structure  

• • Ensure attached structures have the 0–5 Foot Noncombustible Zone, measured from the outermost posts.   

• • • Note: A fully noncombustible patio surface (e.g., concrete slab, pavers) with no cover, or with a fully noncombustible louvered patio cover (e.g., metal), does not require this zone.   

Top of Walking Surfaces  

• • Clear all vegetative debris, wood planter boxes, and climbing vines.   

• • Limit to no more than 10 small, noncombustible potted plants (e.g., clay, ceramic). Each should be less than 36 inches tall (including the pot) and easy to move indoors during Red Flag Warnings or extended absences. Large planters with trees should not be used.  

• • Use noncombustible-framed seating (e.g., cast iron, aluminum, metal). Remove combustible furniture such as wood, composite wicker, or plastic.   

• • Keep the area within 5 feet of the building clear of combustible accessories such as merchandise, signage, boxes, and deliveries. 

• • Relocate movable items like umbrellas, doormats, and outdoor heaters indoors or at least 30 feet away during Red Flag Warnings or extended absences when facilities may be closed.  

Attached Overhead Structures (e.g., covered patios, commercial pergolas, and awnings)  

• • For attached combustible pergolas, remove roof slats (e.g., wood or vinyl) to ensure no more than 15% coverage of the total surface area. 

• • • Tip: For 2x, boards (e.g., 2×4, 2×6 turned on the 2x side), allow approximately 1-foot spacing between boards.   

• • • Note: For freestanding pergolas see “5-30 Foot Defensible Space Zone”. 

• • For attached solid-covered patios, use a solid Class A fire-rated roof covering such as asphalt shingles, concrete/clay tile, slate, or metal; avoid wood roofs, plastic corrugated panels, and fabric shades. 

• • Apply at least 6 vertical inches of noncombustible wall covering (e.g., metal flashing, fiber-cement, masonry veneer, or stucco) at the base of any combustible exterior cladding/siding and structure posts.  

• • Keep attached structures free of combustible items (e.g., hanging vegetation, curtains/drapes, combustible furniture, shade screens, and stored items). Shade screens that fully retract into noncombustible housing may be used.  

• • Avoid storing combustible items inside attached open structures (e.g., storage, carports, and garages), if interior walls have exposed combustible material (e.g., wood), enclose the structure.  

Underneath Elevated Ramps, Decks, or Stairs 

• • Remove all stored items from beneath ramps, decks, or stairs.  

• • Clear all vegetation and combustible groundcover, including grass, weeds, plants, exposed weed cloth, artificial turf, and wood or rubber mulch within the 0–5 Foot Noncombustible Zone beneath and around the ramp, deck, and stairs. Replace with noncombustible hardscape such as bare soil, gravel, pavers, river rock, decomposed granite (DG), or concrete. 

• • Apply at least 6 vertical inches of noncombustible material at the base of combustible posts, supporting walls, and stairs using metal flashing, fiber-cement, masonry veneer, or stucco. 

• • Decks 4 Feet or Less above ground level: Enclose the underside to prevent ember and debris accumulation using 1/8-inch or finer corrosion-resistant metal mesh from the outer edge of the walking surface to the ground. 

• • • Note: Install the metal mesh on the outside of any existing lattice.