I recently bought a bath fan but the only vent kits i can find are for direct venting through a wall or a sloped roof but i have a flat roof. In this 1920s home where the exterior brick walls support the roof joists, im afraid to cut out an opening for the 4" vent line if i were to direct vent through the wall since the hold would be within inches under the joists supporting the flat roof. I figured my safest option would be vent straight up through the rood but im not sure if there is a special type of vent cap i need. Can someone point me in the right direction or am i just being paranoid about making a hole through the brick instead?