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Vertical Fenestration of Addition and Existing Buildings

admiralArchArch

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Joined
Nov 30, 2018
Messages
46
Location
middle earth
We are doing a small addition (~3,000SF) to very large school (200,000+ SF). The addition is mostly curtainwall so naturally we are exceeding vertical fenestration limits in per C402.4.1 in 2018 IECC. Trying to run A COMcheck and of course the envelope fails by like -30%.

However, if you look at C502.2.1 you can use the total building fenestration area that includes the existing building. Factoring that in we would be waaaay below 30%, however there is no way to document this via COMcheck. If I plug into COMcheck approximated numbers for existing wall, floor, roof, windows it does not help even using code minimums (probably because the UA values skyrocket).

How do we document compliance without a comcheck as that is what our AHJ is going to be looking for?
 
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