Abstract: An improved modular building (10) is disclosed, the building (10) comprising sidewall modules (11), and ceiling modules (12). The sidewall modules (11) comprise a primary frame (19) to which a secondary frame of furring strips (26) is attached. The sidewall modules (11) further comprise foam insulation (27) molded around the primary and secondary frame to define exterior and interior planar surfaces (28, 29). The ceiling modules (12) comprises frame means supporting a plurality of ceiling joists (67), and foam insulation (27) dispersed within the frame means and between the ceiling joist (67) so as to define upper and lower ceiling surfaces (68, 69). In one embodiment, floor modules (14) are also provided. A method for fabricating the various modules of the present invention is also disclosed.