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Measurement of Emergency Escape and Rescue Opening EERO in a Single Family Dwelling (SFR)

jar546

jar546

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According to the 2021 IRC Section R310.2.3, the bottom of the clear opening of the emergency escape and rescue opening should not be greater than 44 inches from the floor. Should this height be measured from the bottom of the window without the frame, or with the frame?
 
Right, the operative word is “opening”. It could be a window, or also a solid door, a hatch cover, etc., so the focus not on glass or other frame materials. Focus on the void space available when the opening is opened.

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Mr. Inspector said:
How do you measure this opening?

View attachment 13614
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I would measure it to the lowest point at which the opening provides a minimum of 20" of net clear opening width and min 24" opening height. That point need to be at or below 44".

From the 1997 UBC Handbook, section 310.4:
"The dimensions prescribed in the code... are based on extensive testing by the San Diego Building and Fire Departments to determine proper relationships of height and width of window opening to adequately serve for both rescue and escape. The minimum of 20 inches for the width was based on two criteria: the width necessary to place a ladder within a window opening and, secondly, the width necessary to admit a firefighter with full rescue equipment.​
The minimum 24-inch height dimensions was based on the minimum necessary to admit a firefighter with full rescue equipment."​

From this I conclude that a 20x24" rectangle must be achievable no matter the shape of the opening in order for successful firefighter passage. This gets us about 3 SF area. The remaining 2.7 SF of area needed to achieve the 5.7 SF required for EEROs can come from the leftover space of the octagon beyond that core 20x24 dimension.
That 5.7 SF number drops down to 5.0 SF at the ground level. I assume that is because firefighters would not be using a ladder, so the ladder rail extensions don't get in the way of rescue.


1718140467188.png
 
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Yikes said:
I would measure it to the lowest point at which the opening provides a minimum of 20" of net clear opening width and min 24" opening height. That point need to be at or below 44".

From the 1997 UBC Handbook, section 310.4:
"The dimensions prescribed in the code... are based on extensive testing by the San Diego Building and Fire Departments to determine proper relationships of height and width of window opening to adequately serve for both rescue and escape. The minimum of 20 inches for the width was based on two criteria: the width necessary to place a ladder within a window opening and, secondly, the width necessary to admit a firefighter with full rescue equipment.​
The minimum 24-inch height dimensions was based on the minimum necessary to admit a firefighter with full rescue equipment."​

From this I conclude that a 20x24" rectangle must be achievable no matter the shape of the opening in order for successful firefighter passage. This gets us about 3 SF area. The remaining 2.7 SF of area needed to achieve the 5.7 SF required for EEROs can come from the leftover space of the octagon beyond that core 20x24 dimension.
That 5.7 SF number drops down to 5.0 SF at the ground level. I assume that is because firefighters would not be using a ladder, so the ladder rail extensions don't get in the way of rescue.


View attachment 13616
Click to expand...

This sounds good but if i did not know this I would not know that the code means a minimum of 20 x 24 " rectangle or even a square opening. I think a round or oblong could comply to the code without the minimum 20 x 24 rectangle opening. Should be in the code.
 
Mr. Inspector said:
This sounds good but if i did not know this I would not know that the code means a minimum of 20 x 24 " rectangle or even a square opening. I think a round or oblong could comply to the code without the minimum 20 x 24 rectangle opening. Should be in the code.
Click to expand...
It is already there:


R310.2.2 Minimum Dimensions​


The minimum net clear opening height dimension shall be 24 inches (610 mm). The minimum net clear opening width dimension shall be 20 inches (508 mm). The net clear opening dimensions shall be the result of normal operation of the opening.

If it is not 20" wide it doesn't count as part of the area of the opening.....
 
I don't understand why the size of the opening is so important if the firemen can't open the window anyway from the outside and they just smash the glass and the framing anyway.
 
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