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Quicker Coffered Ceilings, continued

BEAM BOTTOMS

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.

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11. Few rooms are square. Use a protractor to gauge the proper miter angles, or just overlap the boards and mark the cuts.

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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 right directions.

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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.

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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.

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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.

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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 straight.

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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.

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BEAM SIDES

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.

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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.

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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.

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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.

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