Flashing and/or sealing for vent through built-up roof (BUR)?
As a temporary fix, spread a layer of Henry Roof Patch around the area where the Pipe Flashing will go. Then press the boot down into the cold patch. Install a screw into each corner and attach the boot to the roof. Make sure the screws are long enough to go into the decking material. Spread some cold patch over the entire boot, especially the edges and at the top. Then cut in some Glass Fabric Membrane at the edges and top. Finish it off with a second coat all over the boot. I usually tar all the way up the pipe and lip down inside the pipe as well.