I need to install some windows. It is a old Chicago home with double brick wall construction which did not have wooden framing before. I installed a wood frame wall behind the double brick wall and set the frame opening to be approximately the same width and height of the original brick opening. My thought process was that once I set the window in the opening.. I can just stuff backer rod, caulk and seal between the window and brick.

 

This would be a very thick bead of caulk since the windows I already ordered are 1/2 inch smaller in both dimensions of the R.O.
The other plan was to get metal trim to go around the window and water proof that way.. but it occurred to me that I did not build a frame around the brick RO to wrap with metal.
So I'm lost as to how to proceed with the water proofing(back of brick.. .5" gap. wood framing) I'm leaning toward the just caulk around method after stuffing in backer rod in the crevice. I was wondering if you would be able to help me. Thanks.

 

View of brick opening condition nd gap between brick and wood framing.

Front view of opening. Framing not completed in this photo.

Disregard the top arch opening... The framing is complete for the opening. Need to take better pictures later.

General over view of window openings. Need a closer look. Will take more pictures later.

 

Since caulk is going to be your means of waterproofing and you have such a large gap, you might want to get some pvc trim and build yourself a thin frame to go around the window-brick perimeter.

Center the windows as best as you can in your rough opening with shims... Figure out what lengths you need to trim the outside, then cut pieces to fit. Maybe they would be 3/8" x 1 1/4". Shoot the corners together with a brad nailer to make a frame. Then shove that frame into the gap between the window and brick. Shim it as needed. Add a couple fasteners if needed. But mainly you will be caulking the pvc trim to the window on one side and the pvc trim to the brick on the other.

Menards Lowe's and HD all have pvc trim in 1x4, 1x6, 5/4x4, 5/4x6, etc. Or you can look in the trim dept for some other kind of pvc trim you could cut to size on a table saw, and make it work.

You want to use a sealant that sticks to pvc and vinyl well... OSI Quad Max or Vulkem would be good choices.

 

Will you be installing some sort of flashing with a drip edge over the top of the windows to direct water running down the bricks above away from the windows?