What's the best practice for non-90 degree corners on drywall / plasterboard?

Question

I am putting up some drywall in my basement which has been tanked out. I'm using metal C-Stud to keep the plasterboard away from the walls.

Am just about to board round the bay window and wanted some advice on how to manage the angles to make sure I get a nice sharp finish.

External 90 degree corners are fine, as I can just put corner skim beads on. However, how do I do the following (see diagram):

A. Internal 90 degree corners I have seen various methods - mainly in the US using paper tape. Is this standard practice in the UK? I'm using scrim tape for the butt joints. Would I use this for an internal corner too? Have heard it can be a pain to put up in corners.

B. Internal non-90 degree corners I presume whatever I do for A will work for B too? Also, should I bevel / chamfer the edge of the board to get a tight joint at B?

C. External non-90 degree corners What should I do at C. to get a neat edge? Edge beads on the topmost sheet of drywall?

Answer 1

Use scrim tape on both 90 degree and non-90 degree internal corners. I've never had a problem with it in internal corners, though I don't do much plastering.

You can use skim beads on non-90 degree external corners; it might help to squash them out to open further and better fit the profile of the corner.

Don't forget to scrim tape the straight board joints too in order to help prevent cracking in the future.