Most buildings that burn in a wildfire are lit by embers. Wind can carry them a mile or more ahead of the flames, and they can keep landing for hours after the fire front has moved on. An ember needs something small and dry to land on: leaves in a gutter, bark mulch against a wall, a cushion on a balcony. Hardening a building means taking those away and closing the gaps embers use to get inside.

Apartment and commercial buildings have more of these gaps than a house. They have more walls, more vents and more balconies, and more people storing things on them. Most of the work is maintenance, and much of it is cheap.

Start with the first five feet

CAL FIRE calls the ground within five feet of a building Zone 0, and it matters most. Anything that burns there puts flame directly against your walls and eaves.

• Replace bark and wood mulch with gravel, pavers or bare soil.
• Remove shrubs growing against the building, and keep tree limbs at least ten feet from the roof.
• Replace the last five feet of any wood fence or gate that meets the building with metal.
• Move firewood, pallets, lumber and spare materials away from the walls.

Beyond that, many California fire hazard areas require up to 100 feet of defensible space. Keep grass short, space out plants and clear dead vegetation.

Close the openings

Embers get inside through vents, gaps and broken glass.

• Vents: cover attic, crawlspace and foundation vents with metal mesh of 1/8 inch or finer, or replace them with ember-resistant vents. Plastic and fiberglass screens melt.
• Roofs and gutters: aim for a Class A roof when you reroof. Clean gutters and roof valleys before fire season and after storms, and consider metal gutter guards.
• Eaves: open eaves trap heat and embers. Enclosing them with noncombustible material helps.
• Windows: heat breaks single-pane glass and lets embers in. Dual-pane windows with at least one tempered pane hold up far better.
• Siding: keep at least six inches of noncombustible surface between the ground and the bottom of any wood siding.

Balconies, carports and trash enclosures

This is where apartments and commercial buildings differ most from houses.

Balconies collect things that burn: cushions, rugs, boxes, brooms, dry plants. The California Fire Code generally bars charcoal grills and other open-flame cooking on combustible balconies and within ten feet of combustible construction, with limited exceptions such as sprinklered buildings. Put the rule in your lease and enforce it. When a Red Flag Warning is issued, ask tenants to bring cushions and loose items inside.

Large dumpsters belong away from walls, eaves and openings. The fire code generally sets five feet as the minimum. Wood trash enclosures next to a building are worth replacing with block or metal. Carports and covered parking are often open wood framing, so keep the space around them clear and don’t let them turn into storage.

Walk the property and write it down

Walk the property each spring and again before the fall winds. Look for torn vent screens, full gutters and anything stacked against a wall. Photograph what you find and what you fix, and keep the receipts. Before fire season, send tenants a short notice covering balcony storage, evacuation routes and how you will reach them.

What it means for your insurance

Carriers writing property in wildfire areas look closely at these details, and documented mitigation can help keep a building insurable. California’s Safer from Wildfires regulations also require insurers to recognize certain mitigation steps in their pricing. Before you start a project, ask us how your carrier treats it, so the work you pay for counts.

Hardening helps, but it can’t fix a market where coverage keeps getting harder to find. Our wildfire page explains the changes to the California Standard Fire Policy we are pushing for.