Windows and doors: closing the gaps heat and embers find

Why windows fail

Glass is the weakest part of a window. Radiant heat from a burning shrub, fence or neighboring house can crack ordinary glass, and once it falls out, embers and flames have a clear path inside. Windows near anything that can burn are at the greatest risk.

Glass: tempered and dual-pane

Tempered glass is far more resistant to heat than regular annealed glass, and even one tempered pane helps. Dual-pane windows perform better than single-pane, and dual-pane windows with tempered glass perform best. The higher level of the IBHS Wildfire Prepared Home program calls for dual-pane windows with tempered glass in both panes.

Frames

Vinyl frames can soften and pull apart under radiant heat, opening gaps around the glass. If you have vinyl windows, look for ones with a metal reinforcement bar inside the frame. Metal and wood frames hold their shape better. California's wildfire building code for new construction allows any frame material, so the glass is where to spend first.

Screens and shutters

Metal window screens help block embers and reduce radiant heat reaching the glass. Fiberglass and vinyl screens can melt. Noncombustible shutters add another layer of protection, especially on sides of the house within about 30 feet of a neighbor's home.

Exterior doors

Doors fail at the gaps, not the slab. Embers blow in under the door and around the frame.

• Install weatherstripping around the frame and a sweep at the bottom of every exterior door.
• Solid core wood, fiberglass or metal doors resist fire better than hollow core or doors with large glass panels. Any glass in a door should be tempered.
• Keep doormats and furniture away from the threshold.

Garage doors

The garage is often the weak point of a house: big gaps around the door, and a room full of gas cans, paint and cardboard behind it.

• Seal the sides and top of the garage door with weatherstripping, and add a bottom seal.
• Store flammable liquids in approved containers, away from the door.
• Know how to open the door manually if the power goes out during an evacuation.

Windows and doors checklist

1. Check each window for single-pane or untempered glass.
2. Move plants, furniture and firewood away from windows.
3. Replace fiberglass or vinyl screens with metal screens.
4. Weatherstrip exterior doors and add door sweeps.
5. Seal gaps around the garage door.
6. When replacing windows, choose dual-pane with tempered glass.

This guide is general information, not professional advice. Building codes and defensible space rules vary by state, county and fire district. Your local fire department or a qualified contractor can tell you what applies to your home. No home is fireproof. Read our full disclaimer.