Exterior Peeling Paint

Peeling paint is essentially an adhesion issue— the paint is not bonding to the substrate or to previous coatings. Trouble shooting the cause of the peeling is crucial if we are to solve the customer’s problem. Unless the cause of the peeling is identified and corrected, the problem will persist.

There are two types of peeling problems: inter-layer peeling (peeling between layers of paint), and peeling down to bare wood. Identifying the type of peeling is the first step in troubleshooting the problem.

Inter-layer peeling occurs when the bond between one coat of paint loses its bond to the previous coat. This will be evident when previous coatings remain on the surface, i.e., bare wood is not exposed. With few exceptions, inter-layer peeling is the result of poor preparation during a previous paint job. However, it remains necessary to identify the specific cause, that is, what steps in preparation were omitted or performed inadequately.

The most common causes for inter-layer peeling are painting over a dirty or chalky surface, or applying a latex paint over a hard, glossy oil paint. It is important to identify the extent and location of the peeling. Small, isolated areas of peeling represent a considerably different problem from extensive peeling. Isolated peeling may be caused by external factors (such as a leaky faucet or splashing from a downspout).

Peeling to bare wood is evidenced by the presence of bare, or primed wood. This type of failure is typically has three causes: insufficient ventilation of the house, the presence of excessive coats of paint, and the use of inferior paint. Again, the extent and location of the peeling is an important part of troubleshooting the problem.

When peeling is extensive, the first step is to inspect the ventilation system. Inadequate ventilation is common on older homes. A house should have 1 square inch of net free ventilation per square foot of attic space, evenly divided between intake and exhaust.

The next step is to determine the number and types of coatings previously applied to the house. As paint ages, it loses flexibility, resulting in stress cracks in the paint film as it expands and contracts. These cracks permit moisture intrusion into the substrate and/ or under the paint film. Complete failure can result quickly as the problem worsens.

In such cases, complete removal of all paint or replacement of the affected surfaces are usually the only viable corrective actions. The type of substrate will determine which option is more economically sensible.

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