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Caulk - Paint Cracking or Crawling

DESCRIPTION
The cracking of the paint film over a caulked area.
POSSIBLE CAUSES
  • Using caulks that are not paintable. Before using caulk, make sure it indicates paintable on the packaging.
  • Applying paint over a partially dried bead of caulk, the paint dries first, forming a film. As the caulk dries, it shrinks and causes the paint film to stretch and crack.
  • Applying caulk when the air, surface, or caulk temperature is below 40 degrees F, and the caulk is not designed for these conditions.
  • Caulking joints in excess of 1/2" in width or depth. If the opening is 1/4" or greater, for maximum performance, prevent three-point adhesion with backer rods or bond breaker tape. Three-point adhesion problems occur in cracks when the sealant adheres to the walls and the bottom of a crack, and a significant amount of flexibility is lost. Two-point adhesion – wall to wall in a crack – using backer rods or bond breaker tape offers the maximum flexibility and performance.
SOLUTIONS
Prime first, then apply caulk only when temperature of surrounding air, surfaces to be caulked, and caulk are all above 40 degrees F. Do not apply when rain or freezing temperatures are expected.

Joints more than 1/2" should be filled within 1/2" of the surface with polyurethane rod or closed cell urethane foam. Fill the remaining joint with caulk, and tool within five minutes of application.