Section 44F of Chapter 149 of the General Laws is hereby amended by striking the second sentence and inserting in place thereof the following:—Such specifications shall have a separate section for each of the following classes of work if in the estimate of the awarding authority such class of work will exceed ten thousand dollars; (a) roofing and flashing; (b) metal windows; (c) waterproofing, damproofing and caulking; (d) miscellaneous and ornamental iron; (e) lathing and plastering; (f) acoustical tile; (g) marble; (h) tile; (i) terrazzo; (j) resilient floors; (k) glass and glazing; (l) painting; (m) plumbing; (n) heating, ventilating, and air-conditioning; (o) electrical work, including direct electrical radiation for heating; (p) elevators; (q) masonry work; (r) concrete floors and other miscellaneous concrete; and (s) any other class of work for which the awarding authority deems it necessary or convenient to receive sub-bids, provided that the awarding authority may, in addition, receive a combined sub-bid on the marble, tile and terrazzo work, but in that event, the marble, tile and terrazzo work shall each be a class of work for which the sub-bidder must list the information in a clearly designated place on the bid form for that purpose.