Quicker Coffered Ceilings, continued
10. Allow the adhesive to dry overnight before installing the
beam bottoms — adding too much weight too soon might
spoil the job. We always start on the perimeter walls, though
in some cases, it's best to run the beams first. The design of
the ceiling will determine the right procedure.
11. Few rooms are square. Use a protractor to gauge the proper
miter angles, or just overlap the boards and mark the
12. Use a square to tie the marks together while the board is
still in place, just to be sure the miters are aligned in the
13. We use a 1/4-inch slot cutter mounted in a router to make
the kerf. A biscuit joiner will work, too, but a biscuit is
always a little sloppy and won't register the two pieces
perfectly flush, like a spline will.
14. We cut splines from 1/4-inch MDF because it's exactly the
right thickness. Glue the kerf on the installed piece and
insert the spline, then apply a liberal amount of glue to all
surfaces of the spline and to the shoulders of the miter before
installing the second board.
15. Install the center beam bottoms next, splining those butt
joints to the perimeter soffit. Cut all the pieces a hair long
and spring them into place. Run the kerfs long so splines can
be slid into place after the pieces are in position. Remember,
the long kerfs will be covered by the beam sides.
16. Fasten the soffit to each piece of backing, but just tack
it with brads so it will be easier to string the beam bottoms
17. On this job, we didn't have to make the beams perfectly
straight. This built-up cornice has large reveals between each
piece of molding, which hides a lot of sin in the ceiling.
Using a string and some long shims, we just got them close to
the eye — within 3/8 inch. But with some designs, the
beams must be installed almost perfectly straight.
18. All of the interior moldings are preassembled. The inside
corners are mitered, glued, and cross-nailed, forming tight,
long-lasting joints. Start with the fascia boards that form the
sides of the beams. On some ceilings, we use baseboard
installed upside down for the beam sides.
19. Measure the pieces tight, then subtract 1/16 inch so
they'll slip easily into place. Since each piece is usually of
a slightly different length, we draw a diagram of the ceiling
grid, mark the front or back of the room, then label each piece
as we measure and cut. We then follow the drawing to assemble
the pieces, so each side will be in the correct position.
20. Every finish carpenter should carry a block of wood for
tapping the sides in place. On WindsorOne's Classical Colonial
frieze (707/ 838-7101, www.windsorone.com), which we're using
here, the cove at the bottom always points back toward the beam
bottom or soffit.
21. Brad nails will not pull the moldings together! We carry
an assortment of quick-grip clamps to squeeze the pieces
tightly together before fastening them.