Q: The ceiling in my garage has a crack in the middle that runs the length of the garage. Every time I patch the crack, it shows up again later. Do you know of a way to fix it so that the crack does not reappear? -- J.J., Evansville, Ind.
A: The ceiling joists of your garage, like most garages I see, do not have enough support to compensate for the weight of the drywall. In fact, most ceiling joists would, over time, sag under their own weight. The ceiling joists serve two purposes: to keep the walls from spreading apart under the weight of the roof and to support the weight of the ceiling.
When a two-by-six joist is used in a typical two-car garage, it has to span up to 22 feet. If you used some of the strongest lumber available, you could span only about 20 feet and the attic space could not be used for storage. What happens is the ceiling joist deflects (sags) and is most notable as the drywall starts to crack. If you have even lightweight storage in the attic, the sag is made worse by the added weight. Strong winds also cause the garage to sway, and this may add to the cracking problems.
Here's what you can do if you have the proper tools. First remove any stored items in the attic. If the ceiling still has a major sag, build a two-by-four wall in the garage to lift and brace the center of the joists.
Next install two-by-four king posts between the roof's ridge and the center span of the ceiling joists, which will be about 11 feet in from the side walls. Install a king post at every other joist, using wood screws rather than nails. Nailing might further damage the drywall ceiling. The king posts will help support the weight of the drywall.
Then cut and install two more two-by-fours set at 45-degree angles with the king posts, and attach these to the roof's rafters. The angled webbing will support the roof and the ceiling joists.
Now you can have light storage in the attic, but keep the stored items nearest the wall between the house and the garage.
(Dwight Barnett is a certified master inspector with the American Society of Home Inspectors. Write to him with home-improvement questions at PO Box 268, Evansville, IN 47702 or send him e-mail at d.barnett@insightbb.com.)
Resources American Society of Home Inspectors (ASHI)
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