Box headers with balloon framing USA

[ramskaar]

Hi all, I am remodeling a 1935 balloon framed house down to the studs.

I'd like to use box headers over some of the windows and doors to reduce thermal bridging and improve insulation. IRC section R602.7.3 is obviously written for new construction.

My question is, does the header depth have to be one of the specified dimensions (9" or 15"), or can it be anything greater than 9" or 15" (I assume less than 9" is a no go)?

Thanks

 

[JohnD]

This is a UK site and our building techniques and terminology are different, as are our dimensions and building regulations.