Abstract: A prefabricated wall panel is disclosed. The panel has a first exterior facing sheet of plywood or OSB and the second interior facing sheet of plywood or OSB. Framing struts are located between the sheets to secured thereto to define a panel volume. A polymeric in-situ foam core is formed inside such panel volume. The overall panel thickness is 4 inches, plus or minus 1 quarter inch. In the finished wall assembly, thickness in combination with a sheet of drywall allows flush mounting of door jambs and window jambs, including flush mounting of trim pieces. The panel has an R value in excess of R20.