Practice questions egress window sf

Good morning ,
I have a question which I really did’nt understand from one of the the practice question. In the practice test asks" MIN required egress window in the sleeping room/ area? Answer is 5.7 sf, ok , next questions is asking min. Width and heights of an egress windows, width 24" height is 20". So in this case 480 sg inch which equals to 3.3 sf , so why saying MIN 5.7 sf , is it internachi’s mistake , or it has some explanation? Thank you in advance

Welcome to our forum Huseyin, come again also.
To answer your question, you don’t multiply them together. They are expressing the minimum width of 24" and a minimum height of 20". So for example, if you have an unobstructed height of 20", the window opening width would have to be 3’-5-1/16 to be exact. Same goes for the minimum width. You would need 24" by 2"-10" to meet the 5.7 sq. ft.
Hope that helps.

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First, welcome to our forum, Huseyin. Enjoy it! :smile:

Second, the larger glass size, from the egress opening size, is because each bedroom/rooms needs a certain amount of exterior light to enter the room so we don’t go looney and the glass to open for egress has to cover other glass, when opened, to meet the requirement.

So, no mistake in the question.

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No mistake. The first two are the minimum individual dimensions. The width can be no narrower than 24 inches and the height can be no less than 20 inches. The 5.7 sqft is the minimum overall size. So a qualifying window can be either the minimum height or the minimum width, but not both because that window would not meet the minimum overall opening size.

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This is how the IRC explains it;

R310.2.1 Minimum Opening Area

Emergency escape and rescue openings shall have a net clear opening of not less than 5.7 square feet (0.530 m2). The net clear opening dimensions required by this section shall be obtained by the normal operation of the emergency escape and rescue opening from the inside. The net clear opening height shall be not less than 24 inches (610 mm) and the net clear opening width shall be not less than 20 inches (508 mm).


  1. Grade floor or below grade openings shall have a net clear opening of not less than 5 square feet (0.465 m2).

Thank you very much for explanations, all cleared. Mr. Marcel, I will check the IRC thank you for referencing the code section.