- Q.Before closing in the walls
on a recent job, we noticed that a 3/16-inch gap had
opened up between the jack stud and the header. Is this
much shrinkage normal? How can we prevent
A.If you are using a solid
header or one made up of 2x10s or 2x12s, the wood
can shrink 3/8 inch across the grain as it dries
from the 19% moisture content permitted in "dry"
lumber to the 9% to 11% moisture content found in a
heated house. Undoubtedly, the header in question
was well along that drying curve before the wall
The shrinkage can be reduced or prevented by
using drier lumber for headers, preferably at about
12%. But lumber that dry may be difficult to find.
Laminated veneer lumber beams are usually more
stable than ordinary lumber. An alternative is to
use a plywood box beam as a header, since plywood
has already been dried and shrinks much less than
solid stock. The American Plywood Association (P.O.
Box 11700, Tacoma, WA; 206/565-6600) publishes
specifications for the design and fabrication of
these beams in a technical bulletin called
Nailed Plywood and Lumber Beams.