Hi okh,
in the meantime I've played with sh3d file, and have opened it with 7zip as archive file. I've found many folders, each of them containing one part of the roof.
I have imported all of them in my personal furniture library, that you can find here (the library also contains other furnitures.
https://app.box.com/s/ojifbte1enann8qgjh3jrxqwt85t7qee