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Width of inner court for natural light- Chicago building code

likeit

Hi,

Appreciate any input into the following for a project..

A 170 feet high office building to be adaptively reused into a hotel.. Planning on 'inserting' a court for natural light and ventilation. According to the following section, would this mean that the minimum width would be 30' for an inner court.. Should be apparent but would appreciate any additional interpretations .. Thanks much all!!

All courts and yards required to serve rooms for natural light or natural ventilation purposes shall comply with the requirements ofthis section.

{a) Minimum width. {i) Every such court or yard shall have a minimum width of3 feet {1,005 mm) up to a height of36 feet above grade and thereafter an additional 2 inches (76 mm) for each 1 foot (305 mm) of height or fraction thereofup to a maximum width of 15 feet (7,620 mm). Above required width values shall apply to outer courts and twice these values shall apply for inner courts.  

 
Aug 23, 16 11:04 pm
BulgarBlogger

FYI, if the Chicago code is based off of the ICC, you can easily join the ICC and call for an interpretation of the code...

The way I understand the code as written (and please confirm/check) is as follows for an inner court:

Your building is 170 feet high. Therefore, you have a minimum of 3 feet for the first 36 feet of building height. After 3 feet, you will consider 170' minus 36' = 134' of building height. 15' x 12" = 180 inches ; 180" / 2" = 90 inches or 7'-6" for the courtyard. 3 feet + 7'-6" = 10'-6". You are now left with 134' - 15' = 119 feet of building height, but this left-over height is a non-issue for light and air according to this code section. Since your courtyard is an inner courtyard, you should multiply the 10'-6" value by 2, yielding a total inner court width of 21 feet. Your 30 foot courtyard therefore complies.

Aug 23, 16 11:28 pm  · 
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likeit

Thanks Bulgar, for your input, but I interpreted the 15' as the max. width that an outer court needs to have, and in your calculations it seems as if you understood the 15' as the max. height that needs to be considered in the calc. I gave your response a cursory glance, thats why I may have misunderstood... maybe should call up ICC. 

Anyone else willing to chime in..

Aug 24, 16 5:46 pm  · 
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The Chicago Building Code isn't based off ICC; it's completely proprietary.

Based on my reading of the code quoted above, it seems like your interpretation is correct.

Aug 24, 16 5:54 pm  · 
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likeit

Thanks David, so the calc. would look something like this

170-36= 134 x 4"=536"/12"=45' . The court width then being 45+3=48', but since the max. width that needs to be provided for inner courts is 30' (double of value for outer courts), we need the provide a min,. width of 30'??

Thanks much again!!

Aug 24, 16 6:03 pm  · 
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I looks like you're calculation is right. However, I found this PDF online that clarifies a little the language in the code. It at least provides a diagram. They do state that the maximum width required, "... of an inner or outer court or yard need not exceed 15 feet regardless of the width calculated ..." By that reading, you only need to provide 15 feet.* You could provide more, obviously, but it wouldn't be required. 

 

*Typical disclaimers apply; YMMV; Subject to interpretation by AHJ; Unless Noted Otherwise; yada yada yada. 

Aug 24, 16 6:20 pm  · 
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archanonymous

wait... are you using the court to provide natural light and ventilation requirements? Such as to sleeping accommodations? If not, then this section doesn't apply at all ( If, for example, you had circulation next to the inner court and all sleeping rooms were on the outer facade with no emergency egress into the court.)

 

Otherwise, i think EI has it right.

Aug 24, 16 7:54 pm  · 
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