Framing/cementing glass block windows?

I'm going to replace by broken/rotted wood framed basement windows with pre-assembled glass block windows. I'm wondering if I need additional framing in the rough opening, and if so how? or if mortar will suffice.

Assuming I only caulk the top of the windows, the RO is 3.5" too wide (1.75" on either side) and 2" too tall.

Is 2" of mortar ok (mostly strength wise)? Should add I some rebar/threaded rod into the opening before mortaring to re-enforce it?

Any other installation advice I should know?

 

1.75 + 1.75 is 3 1/2.

you didn't say what the opening consists of.... masonry on 3 sides and wood on top?

 

err, sorry...yeah 3.5" too wide... reorganized my sentence and added the 3.5" afterwards and wasn't paying attention..

The foundation/opening is a mix of concrete and blue-stone (I think?). It's mostly concrete with some blue-stone visible. So yeah, masonry on 3 sides but a steel header on top.

 

It depends what you use. I would probably use a dry pack floor mud such as this example:

https://www.menards.com/main/floorin...6020106745.htm

Fit the window into the opening... use shims to hold it or anchors if instructed... Mix the dry pack mortar dry enough that it sticks together when you squeeze it with your hand (but not too wet) and pack it in around the window perimeter, tamping it with a 2x4 block and hammer to fill the space around the window. Caulk the perimeter when dry.

note any mfg instructions and follow them if it calls for a caulk gap around the window. If a gap is required you can wrap the window with a sill sealer gasket as needed.

 

Sounds good, thank you for the quick responses!