How do I plaster this window?

[Vermilion]

I am currently covering my garage wall with OSB and drywall, but I've reached a window I don't know how to handle.

I am using 25*50 battens. Behind the battens, I place sill paper partly to protect the wood from moisture and partly to smooth the wall so it becomes completely flat. On the battens, I screw OSB boards and drywall. I leave about a 1cm gap at the top and bottom for ventilation.

But how do I fix this window in a nice way?

 

[Liteavvarje]

Saw OSB neatly and glue it up, possibly smooth with filler, (OSB rough), otherwise use another board then paint, not drywall as it will be hard to get the ends right.

 

[hul]

Otherwise, one suggestion is to use a cement-based board like minerit or similar since it's a garage. The board withstands moisture much better and is more durable. You can also hose down the wall if you want.

You could also use hat channels directly against the wall, making the construction more stable and easier to manage around windows. Hat channels have the additional advantage of not being organic, of course.

Or steel studs work well too, of course.

 

[KalleKe]

I used cement-based board in the window recesses in the basement to avoid moisture problems, and it has worked very well. Should work the same way here as suggested by the previous thread writer

 

[Vermilion]

Saw OSB neatly and glue it up, possibly putty, (OSB rough) otherwise some other board, then paint, not plaster will be difficult to get good at the ends

I'm very new to this area. You're probably thinking of a good idea, but I'm having a hard time understanding what you mean. Are you suggesting I cover the "inside" of the window frame with OSB boards?

I also have access to a good hammer drill, so I could enlarge the opening to make it look more like a regular window? I was just thinking so the boards don't go over the glass blocks and make the opening smaller.