A seal assembly (10) is provided for sealing a core hole (52) formed in a concrete slab (54) having opposite first and second surfaces, with the core hole (52) extending between the first and second surfaces. The seal assembly (10) comprises a cover assembly (12) having a cover plate (14) that is configured for engaging the first surface of the concrete slab (54) and seating over and covering the core hole (52). The cover assembly (12) has a lower plate (16) that is configured for being received within the core hole (52). The lower plate (16) is coupled to the cover plate (14) through a support member (20) so that the lower plate (16) is spaced apart from the cover plate (14) when the cover plate (14) is seated over the core hole (52) to define a cavity between the lower plate (16) and the cover plate (14). A locking element carrier (26) is coupled to the cover assembly (12). A locking element (40) is movably coupled to the carrier (26) and facilitates securing the seal assembly (10) to the concrete slab (54). The cavity of the seal assembly may be filled with an insulating material (62).