Thread: Roof condition

This metal chimney consists of b vent passing through roof and ceiling below, and the remainder if the vent is single wall, venting a medium efficiency boiler (appox 200 K BTU's). The chimney is located above the 2nd floor and the boiler is located on the first floor. The vent is not vertical only, there are some horizontals (approx 4'). The clearance where the B vent passes through is approx 2" clearance to combustibles. The system and home is approx 2 years old. The roof is rubber and has been professionally installed.

Homeowner states original rubber roof at flashing became damaged by the heat so the roofer applied flashing cement to seal the area. As you can see the flashing cement is also being effected by the heat.

It is my contention that neither the rubber roof and the flashing cement should have been damaged by the anticipated amount of heat expected in this area.

Any opinions as to what could cause this?

What could cause this anomaly?

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A b vent chimney in our area needs a minimum clearance,of one inch, to any combustible materials,your picture does not indicate that,that appears to be the problem.

Originally Posted by Harry Janssen

A b vent chimney in our area needs a minimum clearance,of one inch, to any combustible materials,your picture does not indicate that,that appears to be the problem.

You may be on the right track. If you look at the IR scan attached, it is clear that the problem is at the side of the flange against the wall. I think the flange has been cut off the bottom of the flashing.

Looks like the transition is picking up the heat and sending it down to the roof.
Brent should extend well above the brood line before transition to single wall.
Personally I would just use then Bvent all the way to increase draft efficiency at the top