Moisture and warmth will promote decay of most woods. To prevent decay, naturally durable woods or preservative-treated wood must be used when the wood is exposed to moisture.
Decay-resistant woods include redwood, cedar, black locust, and black walnut. Preservative-treated wood is treated according to certain industrial specifications. Preservative-treated wood is most commonly used because of its availability.
Preservative-treated or naturally durable woods should be used in the following locations:
1. On concrete foundation walls that are less than 8" from exposed earth.
2. On concrete or masonry slabs that are in direct contact with earth.
3. Where wood is attached directly to the interior of exterior masonry or concrete walls below grade.
4. For floor joists if they are closer than 18" to the exposed ground.
5. For floor girders if they are closer than 12" to the exposed ground.
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Exterior wall
8" or less
When pressure treated lumber is cut on the job site, apply treatment to the end by soaking or brushing
Protecting Lumber from Decay (continued)
Framing on a concrete slab
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