Hi-
I have an apartment that is part of a 3 story building. My apartment is the top floor. The bath vents make a gradual 90 bend out of the bath fan, using insulated flex duct, and then go straight up out through the modified bitumen torch down roof. The roof has 2 layers of 3" poly iso above the decking, and there is also 8" of open cell spray foam below the decking (above the drywall). The exhaust pipe is 4" round metal duct, and there is a backdraft flap just above the roofline, and then about 16" of pipe before the vent cap (top hat). I am getting lot of condensation in the pipe and its causing some staining on the drywall. Is there any way to bulletproof this install with the pipe in metal going through the roof?
What are the best practices for this set up? I am thinking maybe PVC would be better given it isn't as conductive as metal duct work?
Should I try to add another backdraft flap inside the apartment? I don't know how I would be able to remove the fan without damaging the drywall?
I have an apartment that is part of a 3 story building. My apartment is the top floor. The bath vents make a gradual 90 bend out of the bath fan, using insulated flex duct, and then go straight up out through the modified bitumen torch down roof. The roof has 2 layers of 3" poly iso above the decking, and there is also 8" of open cell spray foam below the decking (above the drywall). The exhaust pipe is 4" round metal duct, and there is a backdraft flap just above the roofline, and then about 16" of pipe before the vent cap (top hat). I am getting lot of condensation in the pipe and its causing some staining on the drywall. Is there any way to bulletproof this install with the pipe in metal going through the roof?
What are the best practices for this set up? I am thinking maybe PVC would be better given it isn't as conductive as metal duct work?
Should I try to add another backdraft flap inside the apartment? I don't know how I would be able to remove the fan without damaging the drywall?