The Drywall Cracks After Applying Joint Compound

Drywall Installation

• If the drywall isn't securely fastened to the studs, excess movement in the drywall can cause cracks to form where it was taped. To test if this is the problem, gently push on the drywall on both sides of where the crack has formed. If there is any inward movement, which may cause the crack to expand slightly as you push, you need to better secure the drywall to the stud by driving additional screws through the drywall.

Poor Tape Job

• Even properly secured drywall will move very small amounts that you can't see when you push on it. These small movements are caused by vibrations and shifting in the house. If the tape wasn't properly embedded in the joint compound, it can crack and blister at the edges. If you've never worked with drywall before, you're better off to use self-adhesive mesh tape instead of traditional paper tape. You won't have to worry about embedding tape into the joint compound, as the mesh tape goes on first and adheres directly to the unfinished drywall surface. The compound then flows through the mesh as it is applied.

Inadequate Interior Environment

• If the interior temperature of the house is too cool or if the house is extremely humid, it can have a negative affect on the joint compound. Low temperatures extend the drying time and can prevent if from bonding with the surface. High humidity will also extend the drying time, because the compound will absorb the moisture in the air. Then, as the joint compound dries, it will shrink and cracks can form.

Improper Application of Joint Compound

• It's important to apply thin, even coats of joint compound on the drywall. Joint compound shrinks as it dries and by applying thin coats, shrinkage will be minimized and reduce the risk of cracks. You're always better off to apply two or three thin coats of joint compound instead of one thick coat.