The existing roof was approximately 82,000 square feet and is separated into two (2) distinct sections comprised of three (3) deck types. The first section measuring approximately 43,500
square feet, dates back to the 1950s, has a gravel surfaced multi-ply built-up roof over rigid insulation which has been installed over an older roof system that was mopped to a sloping “cinder concrete” fill directing water towards perimeter scuppers. This older layer of roofing is comprised of a coal tar flood coat over a ply felt. This original roofing layer is to remain. The “cinder concrete” fill was installed on a 2-inch-thick concrete deck. The original portion of the building also has a tectum deck over the cafeteria (Roof Area A). This tectum deck area has the same flood coat of coal tar that will remain. The second roof section from 1993 is approximately 38,500 square feet of gravel surfaced multi-ply built-up roof over rigid insulation on metal deck. The metal deck is sloped towards roof drains at the center of the roof, except for three (3) areas that use a tapered insulation system to direct water to the drains. Roof cores are included at the end of Section 002300 Roof Core Information. The work shall include the removal and replacement of gravel surfaced multi-ply built-up roof and insulation system, down to existing roof decks or covering flood coat. The new roof system will be a base ply of cold process SBS modified bitumen sheet, over a new polyisocyanurate insulation system and cover board. The modified base ply will then be coated with a two-coat reinforced urethane coating system. The new roof will also include new metal flashings at the expansion joints, roof perimeter fascia, as well as new metal counter flashings at all mechanical curbs.