Drywall Cracking at Expansion Joint

The Facts

• The joints where the edges of two sheets of drywall meet are usually covered by a paper or mesh-based tape and covered with joint compound. Joints that are expected to shift and move usually use expansion joints to deal with the movement. These flat vinyl pieces are attached to the two pieces of drywall with caulk, says Myron Ferguson in "Drywall: Professional Techniques for Great Results." The caulk and metal trim absorb stress and movement better than joint compound and tape, which crack easily.

Causes

• Although expansion joints are designed to prevent cracking, unusually high amounts of tension or movement in the wall cause the drywall to crack around the joint. As the moisture in the air changes from dry winter conditions to humid in summer, lumber in the house framing swells. This pushes drywall joints apart and causes cracking, according to the Structural Building Components Association. When the frame is built improperly, the pressure becomes high enough to crack the drywall even around an expansion joint.

Repairs

• In other drywall joints with cracking, the repair involves adding an expansion joint. If a flexible joint still causes cracks, you'll need to make structural repairs. A foundation problem can be indicated by serious cracks around expansion joints that form when the foundation shifts up and down, says Trained Eye Home Inspection. Straightening improperly built trusses, joists and wall framing requires removal of drywall in some cases but may be the only way to prevent further cracking.

Prevention

• If you know that fluctuations in humidity or soil moisture will cause strong strain on the drywall joints, try adding extra movement in the expansion joints. Use a joint product with a deeper crease of material in the middle of the piece to make the expansion joint more flexible and capable of handling movement without cracking, recommends John D. Wagner for "Drywall: Pro Tips for Hanging & Finishing." Adding a thicker layer of caulk when you attach the vinyl strip to the drywall also adds cushioning.