Aug 14, 2016 · Most drywall cracks occur on the seams, where two pieces of drywall meet. Usually the seams are invisible due to the use of drywall mud and tape. The mud fills in the seam, and the tape covers it up. Cracks form due to stress placed on the seams. He applied the adhesive to the durock, left the seams dry and put the tile over the exposed seams.--so if you're looking at it from behind (we had to remove some drywall from an adjacent room for something else), you'd see the back of the durock, and in the slight seam between durock sheets, you'd see the uncoated back of the tile.

New drywall construction requires the use of tape for the best results. However, if you're mudding a hairline crack in an existing drywall ceiling or wall, you may apply wet joint compound to the crack with a 6-inch taping knife, and smooth it flush with the drywall without using tape. Learn how to use paintable latex caulk to repair ceiling cracks. Find out how to determine if the crack is a drywall seam.