Types of Cracks on Painted Walls

Alligatoring

• If the paint cracks look like small boxes and is flaking, you have a problem with alligatoring. Alligatoring occurs for a variety of reasons. Painting high-gloss surfaces without sanding, using the wrong primer and using old paint are all reasons that alligatoring occurs. Alligatoring also occurs if there are too many layers of paint or if you used paint that was allowed to freeze. Oil paint is more likely to alligator than latex. The only way to fix this problem is to sand the surface until it is smooth and apply the proper primer.

Checking or Grain Cracking

• Checking is when long lines appear with shorter cross lines or check marks. Paint applied to plywood or wood paneling can crack if the wood is repeatedly exposed to moisture. The moisture causes the wood to expand and then contract once it dries out. The repeated movement of the wood causes the paint to crack. When this occurs, you need to sand off the existing paint and apply a new wood primer to the surface of the wood. Then prime the wood with an exterior-grade primer topped with at least two coats of paint to prevent grain cracking.

Peeling

• Peeling occurs when large pieces of the paint crack, blister or peel off the walls. Peeling can occur when the surface was not prepared properly. Proper preparation includes cleaning the surface and either sanding it or applying the right primer. This allows the new coat of paint to adhere to the surface. Peeling can also occur if there is too much moisture. Moisture under the paint evaporates into a gas and causes the paint to blister and peel off.

Cross-Grain Cracking or Crazing

• When oil-based or alkyd paint is too thick, it causes cross-grain cracking, also known as crazing. Older homes that have been painted numerous times can develop this problem. The cracks usually occur parallel to the wood grain with cross-grain cracks that run across the cracks. The only solution to cross-grain cracking is to remove all of the old paint.