Decide which direction you want the beam to run, and then measure across the ceiling to find the middle. Measure 2 7/8 inches from the center, and make a mark. Go to the opposite end of the ceiling, and repeat the process. Use the chalk line to make a straight line from one mark to the other, across the length of the ceiling where the beam will be added. This line marks where the outside edge of your mounting board will be placed. Measure the distance from one end of the wall to the other, for cutting your material.
Install the 2-by-6-inch material flat against the ceiling. Attach it with 12d nails. It is important that you nail the mounting board securely, so take the time to locate the ceiling joists. If a single length of wood is too short, cut pieces square, and butt the ends together for the remaining distance. This material will not be visible after the beam is built but it should follow the chalk line you made.
If the oak 1-by-6-inch material is not long enough to fit in a single piece, cut a 45-degree angle across the face of one end. Start at either wall, and place the oak so that the face of the cut points outward and one edge is butted against the ceiling. Butt the square end against the wall, and use 4d finish nails to attach it to the mounting board every 16 inches. For the next piece, cut it so that the outside edge of the angle fits on top of the piece you have already mounted. This forms a better-looking joint than simply butting square-cut ends together. Repeat this process along the length of the beam, with the final piece cut square and butting against the wall just as you began with the first piece. Repeat this process along the other side of the mounting board, forming the two sidewalls of the beam.
Install the faceplate for the beam. The oak for the face will fit inside the two walls you have already installed, and should be mounted so that it is flush with the bottom edges of both sides. Remember to make your joints using 45-degree angles. Use 4d nails to attach the sides to the face. Be careful that your joints are placed so that there is a continuous smooth face. Use the nail set to sink all nailheads below the surface of the wood slightly.
Mix sawdust with clear wood glue to form a putty-like paste. Dab this mixture into each nail hole or any other minor blemishes that may be visible. This is an old trick used by trim carpenters in fine carpentry. You could use wood putty for this process, but you will match wood color more accurately using actual sawdust from the same lumber.
Sand the beam on all three sides. Use the 150-grit sandpaper first, and sand the joints to remove any jutting edges. With that done, use the 220-grit sandpaper to achieve a smooth surface along the length of the beam on all sides.
Sand the trim material before installing it. Install the 1-by-2 trim along the top corner where the beam meets the ceiling, using 4d finish nails. Do not allow joints in the trim to match up to joints in the beam. Instead, cut 16 inches off the piece to achieve an offset between the two. At each wall, cut two pieces of trim to run between the top piece of trim and the bottom edge of the beam. Cut two more pieces of trim to lay flat across of the bottom of the beam on each end, including covering the ends of the trim you just mounted. The finished trim should cover all spaces where the beam touches the walls.
Set the nails and fill them as before. Sand the joints to make them smooth. After the glue has dried, hand-sand over the nail holes with 220-grit sandpaper to remove any bumps or bulges.
Things You Will Need
- Tape measure
- Chalk line
- Circular saw
- 2-by-6-inch pine
- 12d nails
- 1-by-6-inch oak
- 4d finish nails
- 1-by-2-inch oak trim
- Nail set
- Belt sander
- 150-grit sandpaper
- 220-grit sandpaper
- Oak sawdust
- Clear wood glue
- You could use bracing timbers or jacks to do this task yourself, but it is much easier if there are at least two people working together.
- It may be easier to built the oak beam first, and then mount it, but this will almost always require assistance.
- Dark stains will help hide mismatched grain patterns in your mitered joints.