For the Greenhouse:
Frame wall openings square and 1/2" larger than fan
blade and shutter sizes.
For a Finished Sunroom:
Frame rough openings 3 1/2" larger than fan
and shutter size. Line opening with 2 x 4, offset enough toward outside
to project past siding. Install fan or shutter. Finish inside by lining
rough opening with 1 x 3.