I digress on egress, escape, emergency exit and rescue.

From the chapter 4 section 402 of the 1964 UBC, definitions-

DWELLING: is any building or any portion thereof, which is not an “Apartment House,” “Lodging House” or a “Hotel” as defined in this Code, which contains one or two “Dwelling Units” or “Guest Rooms,” used, intended, or designed to be built, used, rented, leased, let, or hired out to be occupied, or which are occupied for living purposes.

DWELLING UNIT: is one or more habitable rooms which are occupied or which are intended or designed to be occupied by one family with facilities for living, sleeping, cooking and

eating.

So now the the code section pertaining to windows.

1964 UBC
Sec. 1405

(a) Windows. All living rooms, kitchens, and other rooms used for living, dining, or sleeping purposes shall be provided with windows with an area not less than twelve square feet (12 sq. ft.) nor one-eighth of the floor area of such rooms.

The window area in bathrooms, water-closet compartments, and other similar rooms shall be not less than three square Feet (3 sq. ft.), unless a mechanical ventilation system capable of producing a change of air every five minutes and connected directly to the outside is provided.

When such required windows are installed, not less than one half the required area shall be openable.

Required windows shall open on a court, yard, or street either directly or through a porch with a minimum clear height of not less than seven feet (7'). Such porch shall be it least 50 percent open on at least one side.

(b) Room Sizes and Ceiling Heights. Every room regulated by Subsection (a) shall have a ceiling height of not less than seven feet six inches (7' 6") in at least 50 per cent of its required area with no portion less than five feet (5') in height. Rooms used for living, dining, or sleeping purposes shall have an area of not less than eighty square feet (80 sq. ft.). Kitchens shall have a superficial floor area of not less than fifty square feet (50 sq. ft.). Superficial floor area is herein defined as clear floor space, exclusive of fixed or built-in cabinets or appliances.

Now we have to jump to Chapter 33- Stairs, Exits and Occupant Loads, section 3320 Exits: Groups H and I Occupancy.

1964 UBC

Sec. 3320. Every sleeping room below the fourth floor in Groups H and I Occupancies shall have at least one openable window to permit emergency exit or rescue. Such window shall have a sill height of not more than forty-eight inches (48") above the floor and shall provide not less than five square feet (5 sq. ft.) of openable area with no dimension less than twenty-four inches (24").

So it states that the emergency exit and rescue will be 5 sq feet, and a minimum of 24” high or wide. So with a minimum height or width of 24 inches the minimum height or width of the perpendicular side would be 30 inches. The sill height will be 48 inches.


This is why we see so many windows with 48 inch sill heights.

1976 UBC Chapter 14

Exit Facilities

Sec. 1404. Stairs and exits shall be provided as specified in Chapter 33.

Every sleeping room below the fourth story shall have at least one operable window or exterior door approved for emergency egress or rescue. The units shall be operable from the inside to provide a full clear opening without the use of separate tools.

All egress or rescue windows from sleeping rooms shall have a minimum net clear opening of 5.7 square feet. The minimum net clear opening height dimension shall be 24 inches. The minimum net clear opening width dimension shall be 20 inches. Where windows arc provided as a means of egress or rescue they shall have a finished sill height not more than 44 inches above the floor.

2000 IRC (First edition of the IRC)

SECTION R310 – EMERGENCY ESCAPE AND RESCUE OPENINGS

R310.1 Emergency escape and rescue required.

Basements with habitable space and every sleeping room shall have at least one openable emergency escape and rescue window or exterior door opening for emergency escape and rescue. Where openings are provided as a means of escape and rescue they shall have a sill height of not more than 44 inches (1118′ mm) above the floor. Where a door opening having a threshold below the adjacent ground elevation serves as an emergency escape and rescue opening and is provided with a bulkhead enclosure, the bulkhead enclosure shall comply with Section R310.3. The net clear opening dimensions required by this section shall be obtained by the normal operation of the window or door opening from the inside of Escape and rescue window openings with a finished sill height below the adjacent ground elevation shall be provided with a window well in accordance with Section R310.2.

R310.1.1 Minimum opening area.

All emergency escape and rescue openings shall have a minimum net clear opening of 5.7 square feet (0.530 m2).

Exception: Grade floor openings shall have a minimum net clear opening of 5 square feet (0.465 m2).

R310.1.2 Minimum opening height.

The minimum net clear opening height shall be 24 inches (610 mm).

R310.1.3 Minimum opening width.

The minimum net clear opening width shall be 20 inches (508 mm).

R310.1.4 Operational constraints.

Emergency escape and rescue openings shall be operational from the inside of the room without the use of keys or tools.

Now I want to explore some terminology that comes up time to time and why we have some discussion on terms. Quite often I hear the terms “Escape” versus “Egress”, well the modern codes define these windows as “Emergency Escape and Rescue”.  But the older codes definitely use other terms. Here are the three terms used from the codes referred in this articles, Emergency Exit, Emergency Egress and Emergency Escape.

1964- Emergency exit or rescue

1976- Emergency egress or rescue

Modern-  Emergency escape and rescue

So we can see through the code language that these terms have been used synonymously. We will find that the terms “Escape and Egress” get intermingled even within the code.

“Quiet people have the loudest minds”
Stephen Hawking

If you find any errors or have additional information that would expand on any code, building standards or manufacturer requirements please let me know.

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