Paints & Coatings Resource Center

Ask the Expert Question-and-Answer Archive

by Ron Joseph

November, 2003

Painting Over Dry Rot

Q. I own a condo in Boise, Idaho that is about 26 years old and has been painted several times. It is a two story building with wood siding. The owners are considering options that include repainting, ALVIS, new wood siding, vinyl siding and stucco. The architect that was retained stated that the wood was in such condition that it would not retain paint (south and west sides). I bought my unit two years ago and had it inspected and the inspector only noted some small dry rot on the siding near the foundation. I also removed vines from the siding and repainted a significant portion and the paint adhered well.

Question - does painted surfaces lose their ability to hold paint in less than 30 years? Would all the other options (ALvis, siding, stucco) suffer from poor wood quality?

A. If there is a question of dry rot, or the surface quality is poor then the paint will not adhere well.

In a case such as you describe, southern exposure can be very harsh and without the proper maintenance the exposed surfaces may develop dry rot over the years.

Dry rot is not always visible from the surface, it can start from behind or on the back side of improperly protected woods, and eventually work its way towards the surface causing the coatings to fail. A painted surface is only as good as the surface in which it was applied to, if the substrate is sound and the paint is intact then it should render itself to repainting.

By rejuvenating the surface such as sanding or power washing you may create a surface in which the paint may stick, however if the dry rot is advanced there wont be much left for the paint to adhere to. This also would pertain to the other siding considerations that you mentioned above.

I would suspect that there may be a degree of wood replacement in order to assure a good and complete job.

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