Covering up an exterior window

Hello! I'm about to build a room within a room studio in my garage. There are currently 2 exterior windows in the garage and I'm planning on just walling over them with the new interior room construction. I'm being mindful of the 2-leaf soundproofing concept and am wondering if by doing some insulation in the window frame area and then covering it with 2 drywall layers makes those a 3 leaf system when combined with the new interior wall leaf. ?? Not sure if the insulated glass windows can be sealed off in some better way. Maybe better to just put the drywall right up against the glass rather than leave the gap of the frame? Any thoughts? Thanks in advance.

Depends on how you do it if it becomes a three leaf. But I would remove the windows. The exterior shell is the most important part in the goal of high isolation, if you think you can do other things and met the rating that a contiguous exterior shell will give you, well, many have tried and many have cried :) Why could you not remove the windows and continue the exterior facade over the penetrations? One of the things I can tell you that you will have to deal with, depending on the window construction, is the heat that will build up on the interior side of the wall framing. The window will, over a short time, warp and possibly glass will break.

Hmmm. I had not even thought of the window becoming damaged due to heat. The exterior is stucco so I think I was just trying to avoid having to remove the window and then match the stucco patch to the rest of the garage. Sounds like a big task. There are always so many details in the studio construction deal! Thanks for the tip.

Doesn't have to be stucco, you can close them in and make it look like wood shutters or something of that nature, you know, use your imagination.