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When Do You Need More Than One Door? – Spaces That Require More Than One Means of Egress

Sean O'Hara — Mon, 12 Dec 2011 23:46:36 +0000

The 2006 International Building Code spells out the conditions where you are required to have two or more exits or as I prefer to see it, where you can have only one exit from a space. Generally the requirements are straight forward but there are a few complex conditions that I've called out.

The first test is occupant load. For occupancy types A, B, E, F, M, and U you can have up to 49 occupants with one exit. For day care centers in type E you're limited to 10 with one exit. For H-1, H-2 and H-3 you can have 3 occupants with one exit and for H-4, H-5, I-1, I-4, I-4 and R you can have 10 occupants. S occupancy allows 29 occupants with one exit. I-2 has a long list of requirements, let me know if you need to go through them.

The next test is common path of egress travel, basically how far you have to go to get to the exit door. For H-1, H-2 and H-3 you are limited to 25 feet with one exit. For other occupancies you're limited to 75 feet with one exit. There are several exceptions. If you have a group B, F or S and a sprinkled building you can go 100 feet on one exit. If you have a group B, S or F and no more than 30 occupants you can also have 100 feet to get to the one exit. Group I-3 is allowed 100 feet. In a sprinkled R-2 building you can go up to 125 feet. Assembly spaces have a number of additional requirements, again just let me know if you need them.

Finally there are a number of cases that always require two or more exits. Boiler, incenerator and furnace rooms over 500 sf or over 400,000 Btu in fuel fired equipment require two exits. Refrigerator machinery rooms over 1,000 sf require two doors. Refrigerated rooms over 1,000 sf and maintaining a temperature below 68 degrees require two exits.

Please note that there is a different set of requirements for buildings with only one exit than this list for spaces with only one exit. I'll cover that in a future post.

Originally posted 2009-03-30 00:01:33.

Egress Windows and Emergency Escape

Sean O'Hara — Wed, 24 Aug 2011 02:42:58 +0000

The International Residential Code spells out a number of code requirements for egress windows and emergency escape in houses and other residential buildings.

First, you're required to have at least one egress window or door in a basement and in every bedroom. If you have one in a bedroom in the basement then you don't have to have an additional one elsewhere in the basement.

The bottom of the window (sill height) can't be more than 44" above the floor. The opening must be at least 5.7 sf unless its on the ground floor where it only has to be 5 sf. The minimum opening also needs to be at least 24" tall and at least 20" wide. You also have to be able to open the window from inside without any special keys or hardware.

If you have bars or covers over the window or window well it is allowable, but it has to be operable from the inside without a key.

If your egress window is below grade you need a window well with a footprint of at least 9 sf and measuring 36" minimum in both directions. If it is more than 44" deep you need a permanent ladder with rungs at least 12" wide, no more than 18" of height between rungs and projecting 3" to 6" off the wall.

If the window is under a deck or a porch, you have to be able to open the window fully and have at least a 36" path out from under the deck.

If you happen to be designing a multifamily dwelling there are some exceptions involving sprinklers and corridors along with fire ratings but where you use egress windows the constraints are basically the same.

Of course the question that usually comes up is "why does the opening need to be so big, I'll get out of a tiny window if there is a fire." The explanation that I've heard is that it has more to do with the size of an opening needed for someone to assist you in escape. The firemen need a bit of maneuvering room to haul you out.

To help you in your design, most manufacturers list which of their windows meet the egress requirements. There can be a bit of variation depending on frame sizes and hardware differences from one manufacturer to another. I've posted more information on common sizes for each operation here.

Originally posted 2008-10-07 10:32:13.

Windows Close to the Floor

Egress Windows Swinging In – Acceptable in Building Code

Sean O'Hara — Sat, 11 Jul 2009 06:49:52 +0000

The International Building and Residential Codes do not specify that egress windows have to swing out. The codes only specify the opening size and location required for the window. In fact, with the European tilt and turn window, they only open in.

I received this question from a reader of the blog, if you have any, please email them to me.

Common Egress Window Sizes and Operation

Sean O'Hara — Sat, 08 Nov 2008 07:01:41 +0000

I recently posted an article on the rules behind egress windows. I realize that knowing the rules doesn't necessarily mean that you know the most common window sizes for each different window operation. So here are the basics and some links to the Anderson Window catalog as a guide:

Casement windows are minimally 2'-4" wide by 3'-4" high. For many casement windows you'll need to order egress hardware which allows the window to not only swing open, but also swing away. Also remember that the sill can't be more than 44" above the floor so you may end up with a taller window for a head height over 6'-8". Anderson's Casement Sizes

Single or double hung windows are minimally 3'-0" wide by 4'-8" high or 2'-8" wide and 5'-6" high. I've seen a 2'-6" wide by 5'-0" high egress window but not all manufacturers make this window size. Anderson's Double Hung Sizes

Slider windows are minimally 4'-0" by 4'-0". Again, watch the maximum sill height. Anderson's Glider Sizes

I've included the links to the Anderson catalogs because they are very clear which of their windows allow for egress. Many manufacturers will call this out in their size charts. I'd suggest checking the specific sizes with the manufacturer that you intend to use and always specify which windows are intended for egress.