Specifications include, but are not limited to: The existing Building M is heated using roof top units mounted over roof Tbeams. Some roof top units require replacement and will be located in the same locations as the removed units. Compare existing conditions to conditions with the new roof top units. Note that the original built up roof was replaced with a PVC membrance roof. It is believed that 3" of rigid insulation underlies the membrane roof. Determine uniform load on beam from lightweight topping. Note, that typical beam has 4 4'x8' skylights spaced along each side of beam at 19' centers. Approximate loading as uniform along the length of the beam. New MU unit represents a 0.1% increase in overall moment on the existing Tbeam. This increase is insignificant and the beam is adequate for the minor increase in mechanical unit weight. Existing mechanical units may be replaced with new mechanical units weighing up to 2,200 pounds in the same location as the original units.