Cook County, IL - Commercial Roof Installation

Built Up Roofing (BUR) Project

It was really nice working in the Cook County Forest Preserve in the spring of 2005. Besides being surrounded by wildlife for most of every workday, the temperatures were nice for BUR (hot tar roofing).

We were contracted to install eleven built up roofs on the District's comfort shelters.

Photo #1. These systems are true ballasted systems, which means a gravel aggregate is used as weight to hold the roof to the structure. There was no need to prime the concrete roof deck because the spot mopping of the fiberglass base was just needed to hold until we got the gravel on.

Photo #2. The fiberglass felt plies are then laid to manufacturer specifications, in this case (due to the steeper than normal roof pitch) perpendicular to the flow of water and slightly canted to allow water to flow over the lap edge instead of straight down the seams. All three plies are set in a solid mopping of type 3 Steep grade asphalt at the approximate rate of 25 pounds per square per ply. At the perimeter edge, we installed our shop-fabricated 24 ga. pre-finished gravel stop flashing, secured with powder actuated concrete fasteners at 8" on center.

Photo #3. The metal receives an asphalt primer, a coating of roof cement (this is a case where roof cement is supposed to be used), a ply of jute membrane, and an additional ply of fiberglass roofing membrane set in hot asphalt.

Photo #4. The topping of the roof consists of a 60 pound per square floodcoat of hot asphalt with the gravel ballast embedded. Because of the slope of these roofs, we had to apply the floodcoat in two passes to avoid hot asphalt running over the edge of the roof. The second pass received the gravel.

Photo #5. One of the finished roofs from the adjacent work area across the meadow. This one is located across the street from Loyola Hospital in Maywood, IL.