Q.: I am involved with the design of an earth-sheltered home. Some of the concrete walls are to contain strips of wood embedded in the surface for the purpose of attaching brick veneer. I am concerned that the wood may soak up water, expand and rupture the concrete. Do you have any information on this?
A.: A brief item, "Wood Swells," in our October 1978 issue, page 584, recommends against using wood embedded in concrete because wood swells whenever it soaks up water. Embedding wood in locations where joints or cracks would be visible, as in the walls of an earth-sheltered house, is undesirable.
We should note that wood strips are sometimes embedded in concrete to form control joints in sidewalks driveways and patios. This is a different function. It allows movement of the concrete at the joint, and some swelling of the wood can be accommodated there without damaging the concrete. Wood used for such a purpose is usually a rot-resistant wood such as cypress, cedar or redwood, usually primed with a wood sealer.