| What is the best way to tape and mud the joint between a vertical knee
| wall and a 45 degree vaulted ceiling to get the straightest and
| crispest line?
plaster/compound the wall first
snap a BLUE chalk line LIGHTLY along the edge of the wall and ceiling
plaster/compound ceiling to chalk line
The wall runs about 20 feet and the drywall is half
| inch. Due to the underlying wood framing and the 45 degree angle, the
| drywall panels on the vaulted side overhang the vertical side by a
| small amount. Will standard mudding and taping fill the void or should
| the lip be chamferred off first?
no need to chamfer edge
fill void with compound and apply mesh over joint
spread to smooth mesh
apply 2nd coat of compound
re snap BLUE chaulk line
apply 3rd coat compound
I have noticed in other homes that
| this joint tend to be rounded rather than angular.
it was done WRONG
amateurs didn't snap chalk line
| Maybe chair rail moulding is the answer. How do you install chair rail
| between the vertical and 45 degree surfaces?
rip the top with a bevel to match the ceiling angle.
lay flat on wall and lift to ceiling, caulk as needed.