This page shows how to mount a faux wood ceiling beam that spans between two walls and is less than 10 feet long.
1.)Use paper to make a template of the inside dimensions of the beam. Trace it out.
2.)Cut out the paper.
3.) Use the paper to trace the shape onto wooden blocks at least 1 ½" thick. Do this twice.
4.) Cut out the blocks of wood.
5.) Mount the two blocks of wood to the side walls where you want the beam to be. Use construction adhesive for a more stable installation.
Hint: Pre-drill mounting holes to prevent the blocks of wood from splitting.
6.) Measure the distance from wall to wall.
7.) Cut the beam to length.
8.) Dry-fit the beam in place to ensure fit.
9.) Take the beam back down. Put PL Premium Construction Adhesive or Liquid Nails on the edges of the 2 wooden blocks (two sides and the bottom, NOT the top).
10.)Put the beam back up and press it into the glue on the blocks of wood. Use the same screw you would use for a basic installation to screw through the beam into the block of wood. Do this on both sides of the beam as well as both ends of the beam.