I'm working on putting up drywall in a room and have now reached the window.
When I removed the trim around the window, it looked like this:
As seen in the picture, the board is just over 1 cm thick.
Behind the newspaper, you can see the frame.
What should I do with the drywall? Should I lay it in line with the tretex board and then put trim around the window, or do I need to "build out" with a board up to the frame, which is just over 1 cm thick first, and then put drywall on top of the added piece as well?
If the trim is wide enough to cover from the frame to the tretex board, you don't need to fill the entire gap, but you'll probably need to shim the door so that the trim sits straight from frame to board. If the trim is too narrow, you'll have to fill in and place the drywall outside the tretex to reduce the distance.
You want plaster behind the casing. Then you need to apply jamb extension in the small window reveal that is created. 6 mm plaster won't hold without something behind it, so you'll probably need to build up with some board where the tretex ends, especially if you're going to set the casing right there. If you have the opportunity to switch to 13 mm plaster, do it; it's also much easier to joint compound with good results and handle overall.
