Rotted siding

Gene Wengert helps a homeowner with a question about decaying siding. 1998.

by Professor Gene Wengert

Our Condominium Owners Association is experiencing a serious problem with 'brown rot' in cypress siding. The siding is installed horizontally against 2 x 4 studs with foil faced insulations between the studs.

Our climate in Chas., SC has all the negatives - heat and humidity and previous owners have done a poor job in breaking ground contact with 'band boards.' Other contributing problems include minimal overhangs and poor flashing.

Any suggestions on salvaging existing siding would be greatly appreciated as well as suggestions for treating replacement siding.

I assume that the decay is on exterior siding. Old growth cypress should not decay, so the first step is to have the wood positively identified.

Second, in order for wood to decay, it must be wet. (Oxygen and warm temperatures are required as well.) The way to keep wood dry is to use adequate overhang, avoid bushes near the siding that will prevent drying after the rain, don't have sprinklers hit the siding, and keep the wood away from the ground. Further, any coating (clear, stain, or paint) must be waterproof. Coat the siding with an appropriate coating--I am sure that you have seen such coatings advertised on TV. Follow label directions, especially with respect to safety items.

Professor Gene Wengert is Extension Specialist in Wood Processing at the Department of Forestry, University of Wisconsin-Madison.

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