How must fiberglass reinforcing mesh be applied to a wall crack before coating?

• A. Overlay the mesh after final coating is applied.
• B. Place mesh on bare drywall and apply joint compound on top.
• C. Glue mesh to the surface after painting.
• D. Embed the mesh smoothly into a pre-applied layer of joint compound, then cover it completely.

Answer: (D)

Fiberglass mesh works by bridging the crack and spreading any movement across a wider area, so it must be integrated into the finish coat rather than laid on top. The best method is to embed the mesh in a pre-applied layer of joint compound and then cover it completely with another coat of joint compound, smoothing it flush with the wall. This anchors the mesh, prevents edges from lifting, and gives a uniform surface for coating. If you overlay after the final coating, the mesh isn’t anchored and the crack can telegraph through the paint; placing mesh on bare drywall with mud on top won’t embed it; gluing after painting doesn’t provide proper bond or moisture resistance. The embed-and-cover approach is the reliable way to create a seamless repair that lasts.