Fig. 31.
Boards.—These are one inch thick or less.
Matched-boards, or "sheathing," have a groove on one edge and a corresponding tongue on the other (Fig. 31.) Any number of boards can thus be joined to make a wide surface. The edges of these boards were formerly tongued and grooved by hand with "matching-planes," but now this is done by machine, usually with some form of bead or moulding at one edge (and sometimes in the middle) to render the joint less noticeable.
Planks.—These are thick boards,—more than one inch in thickness. Both planks and boards can be of any width or length, the distinction being merely in thickness.
Joists.—These are the same as narrow planks, but of some fixed width, as 2" by 3", which is the same as a 3" strip sawed from the edge of a 2" plank.
Fig. 32.