Are dual pane windows required in California?

Only for new homes and rebuilds in the fire zones the wildfire code covers, and then one pane must also be tempered. There's no rule making existing homes replace windows. The insurance discount accepts any multipane window.

Do I need tempered glass?

For new construction, yes, at least one pane. For an existing home it's the best-supported glass upgrade when you replace windows. IBHS's top-level Plus standard asks for two tempered panes.

Are dual pane windows fire safe?

They're better than single pane, but not enough alone. In LA, many homes had dual-pane windows but few had tempered glass, and plants, fences and hot tubs next to windows broke even good ones.

Are vinyl windows OK in a fire zone?

The code doesn't regulate frame material. Older vinyl double-hung windows without a reinforced meeting rail can fail before the glass breaks, according to the Headwaters study. Most new vinyl windows are reinforced; look for AAMA/WDMA/CSA 101/I.S.2/A440 certification.

Do window screens help in a wildfire?

Yes. A metal screen on the opening part of the window blocks embers if it's left open and reduces radiant heat on the glass.

Does the insurance discount require tempered glass?

No. California's Safer from Wildfires rules accept multipane windows, including dual pane, or functional shutters that cover the whole window.

Windows and doors

Fire-resistant windows. Tempered glass is the upgrade.

Many LA homes already have dual-pane windows, but few have tempered glass, and that's the part that held up in the 2025 fires. Here's what California code requires, what insurers credit, and what to fix around the window itself.

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Updated November 10, 2026

3 to 4x

more heat resistance from tempered glass than ordinary annealed glass, according to the 2024 Headwaters study.

34%

of window frames IBHS surveyed in the Palisades and Eaton fire areas were vinyl. 38 percent were metal.

51% vs 36%

of surveyed homes had double-pane windows in the Palisades vs Eaton. IBHS ties the gap to the Palisades sitting inside a Very High zone where the wildfire code applied.

The short answer

Glass breaks first. Tempered glass holds.

The Headwaters study calls glass "the most vulnerable component of a window." When a window breaks, embers and flames get inside. IBHS saw it side by side in the LA fires: "Only the annealed glass failed; the tempered glazing remained in place."

So when windows are due for replacement, go multipane with tempered glass. Before that, the cheap fixes are around the window: keep plants, fences, hot tubs and furniture away from it, and add metal screens.

What's required

New homes need tempered. Existing homes don't.

For new homes and rebuilds in fire zones, California's 2025 wildfire code (504.8) gives four options for windows, glass doors and skylights: multilayered glass with at least one pane of tempered glass, glass block, a 20-minute fire-protection rating, or a product that passes the State Fire Marshal's window test. The code has no rule on frame material and no screen rule, except that operable skylights need metal mesh with openings of 1/8 inch or less.

No state rule makes an existing home replace its windows. The State Fire Marshal has proposed further window changes, but they aren't final, so we'll update this page if they take effect.

What the code, IBHS and insurers ask for on windows
Who	What they ask for
California wildfire code (new homes)	Multipane with at least one tempered pane, glass block, or a 20-minute rated window
Insurance discount (Safer from Wildfires)	Multipane windows (including dual pane) or functional shutters that cover the whole window. No tempered-glass requirement.
IBHS Wildfire Prepared Home (Base)	No window requirement
IBHS Wildfire Prepared Home Plus	Multipane with at least two tempered panes, a 20-minute rating, or glass block

Sources: 2025 California WUI Code 504.8; 10 CCR 2644.9; IBHS Wildfire Prepared Home 2025 standard.

What the research shows

Dual pane helps. It isn't enough on its own.

Single pane is the biggest risk: A study of California structure losses from 2013 to 2018 found single-pane windows carried a consistently and significantly higher risk than multipane.
Tempered beats annealed: IBHS found side-by-side windows in the LA fires where only the ordinary annealed glass failed. Fire Safe Marin says tempered glass is about four times more resistant to breaking.
Vinyl frames can fail first: The Headwaters study says the glass unit in a vinyl double-hung window without a reinforced meeting rail can fail at less heat than it takes to break the glass. Most new vinyl windows have reinforced rails. Fire Safe Marin suggests looking for AAMA/WDMA/CSA 101/I.S.2/A440 certification.
What's next to the window matters: IBHS documented windows that "failed despite being double-paned with tempered glass" next to a burning hot tub and deck. LA County Fire says to keep woody plants away from the house, especially in front of windows.

Before you replace

Cheaper fixes around the window.

Metal screens: The Headwaters study says a 1/16-inch metal screen on the opening part of a window blocks embers if the window is left open and cuts the radiant heat reaching the glass. Fire Safe Marin reports bronze, PVC-coated fiberglass and aluminum screens all improved how glass held up.
Clear what's in front: Move firewood, furniture, plants and hot tubs away from windows. IBHS's standard keeps hot tubs at least 10 feet from walls.
Shutters: Fire Safe Marin says shutters work against radiant heat and flame, but someone has to close them before leaving. They also count toward the insurance discount if they cover the whole window.
Doors and the garage: Weather-strip any gap wider than 1/8 inch around exterior doors and the garage door so embers can't slip through.

Costs

What window and door upgrades cost.

Installed costs for window and door upgrades
Item	Typical installed cost
Dual-pane tempered metal-clad window, 2x3 ft	About $755 each, plus $400 to $500 for trim and flashing. Two windows on a short wall: $2,200 to $2,500.
Metal storm window	About $333 each
Protective shutters	About $47 per sq ft. Four windows plus one 8x10 door with roll-down shutters: about $8,900.
Metal sliding door with tempered glass	About $2,680
Metal or fiberglass entry door	About $1,250 / $1,520
Metal or fiberglass garage door	About $2,360 / $3,900
Weather stripping	About $530 for a door perimeter; about $280 for a garage door jamb, head and threshold

Source: Headwaters Economics and Quarles (2024), Northern California prices; shutter example from California contractor quotes in the same study. A 2025 Headwaters and IBHS study for Altadena put code-compliant windows at about $3,000 more than standard windows for 10 windows.

How RF1 helps

We check every window and what's beside it.

During the assessment Mark notes window glass and frames, what sits in front of each window, and gaps around doors and the garage. You get a plan that puts the cheap fixes first, with windows timed for when they're due. RF1 coordinates the clearing, screens and weather stripping, and helps you scope window replacement with a qualified installer.

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Questions

Window questions we hear most.

Are dual pane windows required in California?: Only for new homes and rebuilds in the fire zones the wildfire code covers, and then one pane must also be tempered. There's no rule making existing homes replace windows. The insurance discount accepts any multipane window.
Do I need tempered glass?: For new construction, yes, at least one pane. For an existing home it's the best-supported glass upgrade when you replace windows. IBHS's top-level Plus standard asks for two tempered panes.
Are dual pane windows fire safe?: They're better than single pane, but not enough alone. In LA, many homes had dual-pane windows but few had tempered glass, and plants, fences and hot tubs next to windows broke even good ones.
Are vinyl windows OK in a fire zone?: The code doesn't regulate frame material. Older vinyl double-hung windows without a reinforced meeting rail can fail before the glass breaks, according to the Headwaters study. Most new vinyl windows are reinforced; look for AAMA/WDMA/CSA 101/I.S.2/A440 certification.
Do window screens help in a wildfire?: Yes. A metal screen on the opening part of the window blocks embers if it's left open and reduces radiant heat on the glass.
Does the insurance discount require tempered glass?: No. California's Safer from Wildfires rules accept multipane windows, including dual pane, or functional shutters that cover the whole window.

Keep going

Home hardening in Los AngelesThe full order of work, costs and who inspects Fire-resistant sidingStucco, Hardie, vinyl and LP, plus the 6-inch base fix Fire-resistant fences and decksThe fence-to-house connection, decking and under-deck rules Home hardening rankedEvery measure by what it does and costs

Sources

Facts checked November 10, 2026. Costs are rounded from the 2024 Headwaters Economics study for CAL FIRE (Northern California prices; Southern California tends to land within 10 percent). They're a benchmark, not RF1 quotes.

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