Abstract: A building wall structure and method includes an outer row of spaced upstanding studs and a parallel, inner row of spaced, upstanding studs forming a doubled stud wall with a space between the rows. A plurality of wall insulation units are provided each unit comprising a pair of elongated, relatively thin, blocks of cellular foam plastic, one block of each pair being the mirror image of the other. Each foam block has a top face, bottom face and opposite end faces with tongue and groove configuration for sealing with juxtaposed blocks when stacked in vertical courses to fill the spaces between studs in the same row. Each block has vertical recesses in one side face for receiving the major portion of a stud with the minor portion protruding. Tie rod-spacer elements connect opposite studs. Blocks are assembled by omitting several inner wall studs, inserting the blocks and moving them along the space between the rows of studs for erection as an insulative wall between studs.

Abstract: An upstanding side wall comprises wood plank members having opposite planar outwardly facing vertical surfaces. The longitudinal side edges are bifurcated symmetrically with respect to a vertical central plane bisecting the two planar surfaces. The bifurcations are curved in horizontal cross-section to form a pair of curved tongues with an intermediate concave curved recess between the tongues. Each recess receives a mating tongue of an adjacent vertical plank member. Each member is symmetrical about the central plane and also about a midplane perpendicular to the central plane and midway between the bifurcations. Alternate members may comprise members corresponding substantially to a half of such a member cut along the central plane. A low density soft foam sealant is applied in a groove at the bottom of each recess.