Preventing Moisture Problems in Wood Siding in the South

Tests showed that southern pine sapwood gives good. service as siding and trim, if a few precautionary measures are taken. If included in the original design, little additional cost is involved. In existing structures, danger signs show up before decay begins, and a few simple measures will prevent trouble. All tests were conducted at Saucier, Miss. mostly on a frame building (8 by 32 feet) having 34 siding panels approximately 2 feet wide and 4 feet high. On the back of each siding board, about 1.5 inches from each end, two copper roofing nails were set to a depth of 4/16-inch. These were used as electrodes for periodic determination of moisture contents with a resistance meter. Four lots of kiln-dried southern pine sapwood siding were tested. Joints of siding to trim, end treatments, wood sheathing, and fungus infections were investigated. For wood siding in the Gulf States plan for a good roof overhang, preferably more than 18 inches for a one-story house. Install eave gutters to prevent roof run off from wetting the siding directly or by splashing up from the ground. Use wood that is free of stain, mold, or decay. Use no sheathing paper more impervious to water vapor than a breathing paper. Dip siding, preferably for 3 minutes, in a water repellent preservative. After a building has been erected the possibilities of eliminating moisture leakage are restricted. The following corrections can be made: 1) Brush or spray a water repellent preservative into the joints before each repainting. 2) If feasible, add sufficient roof overhang 3) Add eave gutters if not present. In many cases this, plus the use of the water repellent, will correct seepage problems.

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