Creating a Trey Ceiling in the Master Bedroom
for an average handy man it could be a challenge, I do not know what your skill levels are. what type of roof design is over the master bedroom now, Gable, Hip??. is there any skylights over the bedroom.
how high do you want the flat part of the tray to be. I keep them around 16"- 24" from the top plate. the first thing you must do is remove all the ceiling covering and insulation from the ceiling. relocate any electrical wiring that could be running across the ceiling. This could be one big pain in the a$$ if all your feeds come across going to the panel.
Build a wall over your bearing bedroom partition that the ceiling beams are resting on. install the studs so they are on the other side of the ceiling joists from the other room. this way when you remove the bedroom ceiling joists they will not be in the way. the wall your building should rest under the existing roof rafters. which will help support the outside wall from thrusting outward over time. I then install blocking between the rafters over the side partition wall,install a top plate plumbed up from that wall and install studs. make sure the studs are in line with the side gable studs or roof rafters if its a hip roof.
now mark the height of your ceiling along the wall you built over the bearing partition.(snap a horizontal caulk line. from end to end. then level to the outside wall and mark along side of the rafters that are resting on the outside plate. install your ceiling along side of these marks. on the sides of the room where the short rafters are going to run and get connected to the flat, make sure you double these end ceiling beams up. find the pitch of the rafter on the outside wall and the length and make your new short rafters the same so they will mount to the double ceiling joist. Make sure the double ceiling joist are running parallel to the side walls. and check for squareness. once the ceiling joists are installed run a few across the top of these connecting the gable studs to the studs you installed on the side partition wall. this will help tie in the side walls . after you remove the strong backs from the old ceiling.then make your ceiling hip rafters to fit in the outside corners. I use a bevel gauge and a ruler. Install blocking and any nailers that are required. the rest you should be able to do. Just make sure you install insulation baffles under the outside roof rafters be fore you insulate. Good Luck.