While it can be alarming to look up and see cracks in the ceiling, not all cracks indicate serious structural problems. Cracks in the ceiling are a common occurrence, and often their impact is more cosmetic than structural.
Learn how to differentiate minor ceiling cracks from more serious cracks that need immediate attention. Plus, find out how to fix a minor crack in the ceiling from below, without doing major drywall work.
What Causes Cracked Ceilings
Damage From Above
Ceilings aren't just the room-facing part that you see most of the time. Ceilings have a top side, as well. Up in the attic, the ceiling is usually unprotected. With just loose-fill or fiberglass insulation over the drywall, the drywall is prone to damage from anyone who moves around or anything heavy that drops.
Improper Taping Joints
Long, straight cracks that follow the direction of the joists are often the result of improperly taped drywall seams. The tape may not have been applied well before it was covered up with additional joint compound.
Water from the roof, flashing, or vents may leak down onto the top of the drywall ceiling. Water damage may manifest itself as yellow or brown stains or as bubbled paint. Cracks are often part of water damage, as the water may leak into the seams between drywall panels and loosen the joint tape.
While foundation settling is to be expected, structural damage isn't. A home's structural damage can begin in the basement, with the joists, beams, foundation wall, band joist, and sill plate. Working upward, damage can affect windows and doorways, walls, and then eventually the ceiling.
How to Know If a Ceiling Cracks That Are Serious
Long ceiling cracks that run in continuous lines, especially those that match up with wall cracks, often indicate serious problems. The issue, then, goes far beyond the crack. It's a foundation problem, with the ceiling crack being only a minor byproduct. With this type of problem, you will usually have doors that stick in their doorframes and windows that open and close with difficulty. In some cases, the effects are even seen on the exterior, with gaps developing between the house and masonry staircases, pathways, or patios.
If the ceiling crack is accompanied by a significant bow in the ceiling, this usually means a serious problem from above: the attic joists or trusses.
When moving around in the attic, be careful not to step on the drywall between the joists. Attic insulation called vermiculite may contain asbestos. If you see small grayish silver or brown pebbles, call an asbestos mitigation company for testing and removal.
Equipment / Tools
- Utility knife
- Five-in-one tool
- Putty knife
- Drywall knife
- Paint roller and tray
- Drywall jab saw
- Circular saw
- Drywall joint compound
- Paper drywall tape
- Ceiling paint
- 1/2- or 5/8-inch drywall
- 1/2-inch plywood
- Drywall screws
How to Fix Minor Ceiling Cracks
Clean Ceiling Crack
Use the utility knife and five-in-one tool to pry off loose paint and drywall compound. Remove old mesh or paper tape, too. Work lengthwise with the crack, not sideways.
Spread Joint Compound
With the drywall knife, spread the joint compound on the crack. Spread about 3 inches wide. Spread thinly.
Apply the paper tape to the wet joint compound. Center the ceiling crack with the tape, as much as possible. Press the tape with the drywall knife.
Apply Joint Compound
Apply a thin layer of joint compound over the tape. Feather out the edges to cover up the edges of the tape.
Touch up Joint Compound
After the joint compound has dried, sand off any high spots. Touch up any missing areas of the joint compound. This may require a full second coat. Allow to dry and sand to smooth.
Prime and Paint
After the joint compound has dried, prime the area, then roll on ceiling paint to match the existing ceiling paint.
How to Fix Major Ceiling Cracks
To fix major ceiling cracks, you need to access the attic. Attic access doors are usually found in bedroom closets, hallways, or garages. With the flashlight, find the area of the crack. Clear loose-fill or fiberglass batt insulation.
Cut out Cracked Drywall
Use a drywall jab saw to cut out the area of the crack, plus 1 to 2 inches beyond the crack.
Before leaving the attic, measure the distance between the joists. On most homes with joists spaced 16 inches on-center, the distance should be 14 1/2 inches.
Create Plywood Backer Board
Below, cut 1/2-inch plywood 14 1/2 inches wide by the length of the hole you created in the drywall plus 3 or 4 inches extra on both ends, up to 8 feet. Add extra plywood if necessary.
Cut Drywall Replacement Section
Use a utility knife to cut out 1/2-inch or 5/8-inch drywall to match the thickness of the existing drywall. Cut a piece to fit the ceiling cutout.
Place Plywood Backer Board
Move the plywood backer board into the attic and place it over the cut-out area. Temporarily place a heavy item on the board before you go downstairs. The heavy item will hold the plywood in place while you drill from below.
Attach Replacement Section
From below, screw the drywall replacement section onto the plywood with drywall screws. Install additional screws through existing drywall and into the extra plywood backer at each end.
Finish and Paint
Finish the edges of the repaired section with drywall tape. Apply joint compound to cover the edges. Sand. Roll primer over the patch, then paint to match the ceiling paint.
When to Call a Professional
Call a foundation repair company or general contractor if you suspect that the home has foundation damage or damage to the rest of the house.