What type of wood is required for sleepers and sills on a concrete slab that is in direct contact with the earth?

The correct response indicates that either naturally durable wood or preservative-treated wood is suitable for sleepers and sills in direct contact with earth. This is important because wood placed in such conditions is susceptible to moisture and insect damage.

Naturally durable woods, like cedar or redwood, have intrinsic properties that allow them to resist decay and withstand exposure to moisture and insects, making them suitable for underground applications. On the other hand, preservative-treated wood undergoes a treatment process that renders it resistant to decay and insect damage, which is likewise essential for wood that will be in contact with concrete slabs or damp soil.

Both options provide effective solutions to prevent deterioration, ensuring structural integrity and longevity. The flexibility of either choice gives builders some leeway in selecting materials based on availability, cost, and project specifications, thus supporting the use of best practices in construction where moisture management is concerned.