I'm planning to replace some old windows in a 75x48 opening and prefer the look of siding trim separating the windows instead of choosing a factory mulled option with continuous vinyl. The header and sill will span the entire width. I'm considering installing two 2x4s to split the windows. To add a bit of insulation, I'm thinking about putting the 2x4s flat and adding half an inch of rigid foam between them. My thought was that the header, sill plate, and jack studs would provide most of the necessary support. Any thoughts on this approach?
2 Answers
As long as you have a properly sized, continuous header over your opening, you're free to frame below it however you like. Just make sure you pay attention to your flashing detail. I'd recommend treating them like a single unit when applying flashing, instead of handling each window separately.
Luckily, since my window's in a second story tucked under the eaves, I don't think there's much risk of water getting in. The tops of the windows are right at the soffit height, but I plan to tape and add a drip cap at the top, just to be safe.
I had a similar situation with my new addition. I initially needed time to decide on the windows to use, so I got the engineer to draft up a design for a single opening. I ended up with 5.5" between the windows and thought about using a 2x6 turned sideways. Just make sure you understand what the window needs on its sides for proper installation, especially if you're planning this like I did!
I think you'll mostly just need the inside depth of the window behind the nailing fin. I get wanting to insulate between the wood and the interior, especially with 2x4 framing. From what I've learned, mulls are just as deep as the windows and they're really just screwed together. Just play it by ear and you can tweak it in winter if needed! ?
Could you clarify what you meant about flashing? Are you suggesting not flashing the middle studs? I'm in the same boat and was planning to do 9" flashing tape around each window, overlapping in the middle.