Cracking and flaking
Cracking and ultimately flaking of paint can occur for a variety of reasons. Often these failures are due to the fact that the paint has inadequate adhesion and flexibility, both common problems with lower quality exterior flat paints.

When timber is involved, moisture intrusion results in swelling of the wood surface followed by contraction as the wood dries. The expansion and contraction cycles, often aggravated by freeze-thaw cycles, can result in cracking and subsequent paint failure by flaking and peeling.

Cracking and flaking can also result when paint is applied too thinly due to overspreading (higher-than-recommended spread rate) or excessive thinning. These practices tend to diminish the paint's final film thickness, so that it is more vulnerable to cracking and flaking.

Inadequate surface preparation can also cause these failures, especially when paint is applied to bare wood or a very porous surface without first applying a primer. A primer will provide better adhesion and will seal the surface, allowing the next coat (the paint) to perform properly.