In California dwellings, an emergency escape and rescue window must provide a net clear opening of at least 5.7 sq ft (0.530 m²), with a minimum clear opening height of 24 in (610 mm) and width of 20 in (508 mm). At grade-floor sleeping rooms, the minimum net clear opening is 5.0 sq ft (0.465 m²). The bottom of the clear opening may be no more than 44 in (1118 mm) above the floor. All dimensions must result from normal operation of the window. See § R319.2.1–R319.2.3. For non-residential contexts governed by the California Building Code, the same minima appear at § 1031.3.1–1031.3.3.
Where this applies
- At least one operable emergency escape and rescue opening is required in every sleeping room, the room to which a sleeping loft is open, and in basements and habitable attics; openings must lead directly to a public way, or to a yard or court that opens to a public way (§ R319.1).
- A door may serve as the required opening if it is side-hinged or sliding (§ R319.3).
Dimensional and operational notes
- The “net clear opening” height and width are measured through the open sash and must be achievable by normal operation—auxiliary removal of sashes or special actions do not count (§ R319.2.2).
- Opening control devices and security bars are permitted if they can be released from inside without keys, tools, or special knowledge, and otherwise comply with state requirements (§ R319.1.1).
Below grade, under decks/porches
- If the window’s clear opening is below adjacent grade, the area well must provide at least 9 sq ft of horizontal area with a minimum 36 in projection and 36 in width, allow the window to fully open, and include a fixed ladder/steps where depth exceeds 44 in (§ R319.4.1–R319.4.2).
- Windows under decks, porches, or cantilevers must be fully openable and have a clear path not less than 36 in high and 36 in wide to a yard or court (§ R319.2.4).
Existing buildings and replacement windows
- When replacing windows where an EERO is required, replacement units are exempt from meeting new-size minima if they are the manufacturer’s largest standard size that fits the existing frame/opening; control devices are allowed if they do not reduce the net clear opening after release (§ 702.5 and § 702.5.1, California Existing Building Code).
- For changes of occupancy that newly require an EERO, an existing operable window may comply with a reduced minimum of 4.0 sq ft net clear opening, with at least 22 in height and 20 in width (§ 1011.5.6, California Existing Building Code).