United States / Build / Fire-resistant windows
Fire-resistant windows
Program and model
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The answer
Fire-resistant windows in the wildfire codes are about the glass. Where Oregon R327 is adopted, R327.3.6 allows tempered glass, multilayered glazed panels, glass block or 20-minute rated glazing, so dual-pane energy-code windows qualify. California CWUIC wants multilayered panels with at least one tempered pane, glass block, a 20-minute rating, or a product tested to SFM 12-7A-2 (OSFM category 8120). IBHS Wildfire Prepared Enhanced specifies dual-pane with both panes tempered, 20-minute glass or glass block. Dual-pane is not the same as tempered.
- Model code 2018 IWUIC Class 1–2 multilayered glazing
- Model code 2021 IWUIC Class 1–2 multilayered glazing
- Model code IWUIC Class 1–2 multilayered glazing
- Voluntary program IBHS Plus two-tempered-pane glazing
For national windows, the national windows requirement is 2018 IWUIC Class 1–2 multilayered glazing. On national windows, it is shown as model code. Read the national windows rule, then compare 26 matched national windows products.
Review 18 national windows place answers before choosing among national windows records. The national windows links keep the rule, products, and place differences together.
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The rule
Model code “shall be tempered glass, multilayered glazed panels, glass block or have a fire protection rating”
Products matching the model-code floor
Pella 250 Series double-hung window with dual-pane glass Matches 2018 IWUIC Class 1–2 multilayered glazing; 2021 IWUIC Class 1–2 multilayered glazing; IWUIC Class 1–2 multilayered glazing 
Pella 250 Series picture window with dual-pane glass Matches 2018 IWUIC Class 1–2 multilayered glazing; 2021 IWUIC Class 1–2 multilayered glazing; IWUIC Class 1–2 multilayered glazing 
Pella Impervia casement window with dual-pane glass Matches 2018 IWUIC Class 1–2 multilayered glazing; 2021 IWUIC Class 1–2 multilayered glazing; IWUIC Class 1–2 multilayered glazing 
Pella Impervia double-hung window with dual-pane glass Matches 2018 IWUIC Class 1–2 multilayered glazing; 2021 IWUIC Class 1–2 multilayered glazing; IWUIC Class 1–2 multilayered glazing 
Pella Impervia fixed-frame window with dual-pane glass Matches 2018 IWUIC Class 1–2 multilayered glazing; 2021 IWUIC Class 1–2 multilayered glazing; IWUIC Class 1–2 multilayered glazing 
Pella Lifestyle Series double-hung window with dual-pane glass Matches 2018 IWUIC Class 1–2 multilayered glazing; 2021 IWUIC Class 1–2 multilayered glazing; IWUIC Class 1–2 multilayered glazing Additional products matching the voluntary program
No sourced windows product in this directory yet matches the voluntary program.
Questions
What is a 30-minute fire rated window?
A duration rating from the fire-window tests used for rated walls. The wildfire books on this site name 20-minute rated glazing as one path beside tempered and multilayered glass; the question they ask is about the glass, not the minutes.
Do wildfire codes require tempered glass?
California CWUIC requires at least one tempered pane unless another named path is used. Oregon R327 does not: multilayered glazing is enough where it is adopted. IBHS Enhanced asks for both panes tempered.
Do dual-pane energy-code windows satisfy Oregon R327?
Where R327 is adopted, yes as multilayered glazed panels. R327.3.6 allows tempered glass, multilayered glazed panels, glass block, or 20-minute rated glazing. Dual-pane energy-code windows are multilayered. Deschutes County names double-pane windows as a commonly used fire-hardening material. Confirm with the building official. That is not California practice.
Do they satisfy California Chapter 7A or CWUIC?
No. The live California book is CWUIC. Exterior glazing needs multilayered panels with at least one tempered pane, glass block, a 20-minute rating, or a product tested to SFM 12-7A-2 (OSFM category 8120). Dual-pane annealed energy-code glass is not that path.
Is dual-pane the same as tempered?
No. Dual-pane means two or more layers of glass. Tempered means heat-treated glass that resists breaking. You can have dual-pane annealed, dual-pane with one tempered pane, or dual-pane with both panes tempered. Oregon, California, and IBHS Enhanced are not the same combination.
Do I need an OSFM listed window in Oregon?
No. OSFM listing is voluntary for most WUI products. Where R327 is adopted, multilayered or tempered glass is a prescriptive path. Deschutes County will accept OSFM handbook products when those products are shown on the drawings. That is local practice.
Does IBHS Essential require tempered windows?
IBHS Enhanced (Plus) specifies dual-pane glass with tempered panes in both, or 20-minute glass, or glass block. Essential is the ember package (roof, vents, Zone 0). A carrier can still add a window line. Ask the carrier.