The other situation that requires furring strips is a ceiling that's badly sagging. The straight lines of a tin pattern will accentuate the bulge in a badly sagging ceiling. To flatten a ceiling, attach furring strips over shims.

NOTE: A badly sagging ceiling may indicate structural problems. Consult your local building inspector.

TIN INSTALLATION TIPS

• Check and double-check your drawing and chalk lines before you begin installation. Once nailed in place, the panels are almost impossible to remove without damage.

• To make seams less visible, begin installing each part of the ceiling (field, cornice, filler) in the corner farthest from where you most often enter the room (see Fig. A). That way, the overlapping edges will face away from you when you enter the room.

• Work in courses; that is, complete an entire row of panels before beginning the next row.

• If you plan to cut any of the field panels, install the course of cut panels first. If you leave them until last, the imperfect edges you cut will be exposed instead of overlapped by adjoining panels.

• Be careful to align the field panels so that the buttons on adjoining panels overlap each other perfectly.

• You can install panels by yourself, but we recommend you have help. You're more likely to damage or misalign them working alone.

• When you install a panel, nail all the buttons along the two edges that overlap previous sheets. Then drive five or six nails into the middle rows of buttons. The remaining button can wait until all the panels are up.

• If you dent a panel, repair it with auto body filler (found at auto parts stores). First roughen the damaged area with 80-grit sandpaper, then apply the filler. You can restore the shape of the pattern by carving and sanding the filler. This is slow work and the results won't be perfect. So do your best not to damage the ceiling in the first place.

• Finally, don't get discouraged. When I drove the last nail into our tin ceiling, I was thoroughly dissatisfied: The ceiling was full of gaps and misalignments. But after we tightened the seams, caulked all the imperfections and painted, it looked great. I still see our mistakes, but nobody else does.

PAINTING THE CEILING

Tin ceilings are sometimes left unpainted and are then simply coated with clear polyurethane. But if you don't paint, your work has to be perfect; you can't caulk and paint gaps between the parts. So if you want the shiny look of metal and the benefits of paint, use metallic paint (available at paint stores).

Manufacturers give tin ceiling materials a light coat of oil to prevent rust. Wipe away this oil with a rag soaked in mineral spirits. Then prime the tin with an oil-based primer.

IMPORTANT: Don't use latex primer. The water in it will rust metal.

You can prime the ceiling before or after you install it. In a high-moisture room like a kitchen or bath, it's a good idea to also prime the backside of the tin to inhibit rust.

When the ceiling is installed, caulked and ready to paint, wipe it down once more with mineral spirits to remove dust and fingerprints. With the metal already primed, you can use a latex paint, although oil-based paints are less likely to show brush and roller marks. Paint the cornice first using a brush, then switch to a roller for the ceiling itself. A roller with a 3/8-in. nap works well on most patterns.

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1 COVER the ceiling with 1/2-in. plywood. The plywood sheets should run perpendicular to the joists. The ends of the sheets should be staggered and must meet at joists to allow for fastening. Don't place the sheets tightly together. Instead, leave a 1/8-in. gap at the seams to allow for expansion of the plywood in high humidity.

2 MARK the layout of the ceiling using a chalk line. When you're done, you'll have lines marking the upper and lower edges of the cornice, the border that will be covered by filler panels and the field. Correct layout is the most important step in this project. Take your time and double-check your work.

3 NAIL up the field panels first. Begin each panel by nailing into each button along the edges that overlap the adjoining panels. Then work your way across the panel, nailing buttons row by row. But don't nail the buttons that will be overlapped by adjoining panels. Important: Leave nails protruding about 1/4 in. around the perimeter of the field so you can pull them out and slide filler strips under the field panels later (see Photo 9).

4 PROTECT the tin from hammer dents with a nailing shield made of 1/4-in. plywood or hardboard. Hammer in each nail as far as you can with the shield in place, then remove the shield and carefully drive the nail home.

WEAR GLOVES WHEN HANDLING TIN CEILING PARTS. THOSE EDGES ARE RAZOR-SHARP!

5 CUT tin ceiling components with aviation snips. To cut out a circle for recessed lights or ceiling fixture boxes, punch a hole in the center of the circle, then cut an outward spiral. See "For More Information," p. 36, for more on using snips.

6 CUT inside and outside corners in a miter box made from 3/4-in. plywood. Clamp the piece of cornice into the miter box upside down and cut it with a 12-in. metal-cutting blade in a reciprocating saw. Be sure to position the cornice so that the pattern on it will correspond with the other side of the corner (see Photos 7 and 8). For a clean cut, run the saw at full speed and ease the blade slowly through the cornice.

7 BEGIN inside corners with an uncut end of cornice. Then hold a cut piece against it to check the fit. Chances are you'll have to do a little trimming with aviation snips to get a tight fit.

8 FIT outside corners by tacking one cut side in place. Leave the nails sticking out so you can adjust the position of the cornice if need be. Then hold the other cut side in place to check the fit before nailing it. When the corner is done, smooth the sharp edges by filing them lightly with a fine "rattail" (round) file.

9 SLIP the filler strips under the field panels, overlapping the upper edge of the cornice, and nail them into place. At corners, you have to miter the filler. To mark the angle of the miter, cut a filler to the proper width and slip it into place (under the field, overlapping the cornice). Then mark the corner of the field on the filler, remove the filler and draw a straight line from the corner of the filler to the mark.

10 TIGHTEN open seams in the field by lightly tapping a wood block against them. Be careful not to crease the metal. Then fill all the gaps in the field, filler and cornice with caulk. When the caulk dries, you're ready to paint.