Hello all,
I’m planning on installing windows directly above a concrete sill. The sill projects past the window plane, and will have a bevel to shed water. The perimeter of the window will be caulked with backer rod, but at least along the bottom, I’m not sure how to protect against water that might make it past the caulking. Thus, I’m investigating strategies for sealing the joint between (1) the window and the concrete sill, or (2) the sill plate and the concrete sill.
I’m considering 2 construction scenarios:
1. Mounting the window directly over the sill. There will be wood framing around the sides and top of the windows. The windows will have a nailing flange on four sides. My plan would be to remove the flange on the bottom and mount the window about 1/4″ above the sill. Any suggestions about what to use to attach/adhere the window at the bottom? Construction adhesive, epoxy, metal clips…?
2. Frame out all four sides. Same as above but use a 2×4 sill plate to allow use of the nailing flange along the bottom too. I would then just have to case over the lower flange, similar to what I will do on the other sides as well. How about sealing between the sill plate and the sill?
Many thanks in advance again.
Best,
Andrew…
Replies
Just my two cents worth, but if the sill has enough slope, I'd be perfectly satisfied with a good (i.e. proper type of caulk and proper backer details) caulk joint. There's many a high rise out there that depends on caulk to be waterproof.
That said, from a detail standpoint, why not frame all the way around? What kind of wall are you putting this window in?
It's going to be a window wall of sorts (ie. minimal framing). The lower 2/3 of the wall is existing solid brick. This we are capping with several segments of precast concrete sills, and our window and framing will sit on top of that up to an existing shed roof.
I would order PVC windows 1/4 inch smaller thatn the opening ( Check to ensure level and plumb opening ) then foam the window in place. Wood return or drywall return into the window and after the bead of caulk on the outside your done. Plumb level airtight watertight
Have a good day
Cliffy
Actually, they will be aluminum clad wood windows. I have been advisd to do similar to what you suggest, but with construction adhesive.
Thanks.