Sagging ceiling needs a lift

Q: Last spring, my roof sprang a leak and water stained the ceiling in my daughter’s second-floor bedroom. We fixed the leak and repainted the ceiling. Now the new paint is cracked and, looking closer, I noticed a seam appearing along the ceiling and small, round depressions — screw holes, perhaps? What’s going on? — Laura L., Wytheville, Va.

A: The ceiling is starting to sag downward, it appears. But all is not lost — because you’re describing a wallboard ceiling, you can shore up the sagging fairly quickly.

First, make certain that no other water damage is occurring by checking the attic or crawlspace above for dampness over or near the bedroom ceiling. You also should be able to determine the extent of the damage from the old leak, and make sure no mold has taken hold on the underside of the wallboard. Fix any leaks before fixing leak damage.

To repair the sag, prop up the wallboard with a T-brace. You can make this yourself — measure the distance from the ceiling to the floor, and cut a 2-by-4 board to that distance, plus one-half inch. Cut a second 2 by 4 to a length of 4 feet and attach it to one end of the long board to make a “T.” Set the cross-piece (the top of the T) at the center of the sagging ceiling, lengthwise. Place the bottom of the brace atop a piece of plywood. Slide the bottom of the brace forward until the brace is completely straight.

To secure the ceiling, place new wallboard screws along the popped seam (or joint), about 4 inches from the old screws. Be sure to screw them into the ceiling joists — the wooden beams above the ceiling. Wallboard’s strength is in its paper skin, so screws should depress the paper without breaking through.

For sagging sections that aren’t along the joint, place screws through them and into a joist. Once fixed, repair the surface by scraping away chipped paint and sanding rough areas. Place wallboard tape over the repaired seam, then smooth compound over the area and feather. Let dry, then repaint.