bathroom exhaust

Does anyone have a good picture of mold in an attic caused by a bathroom exhaust fan terminating in the attic. I have a builder that has allowed the exhaust pipe to terminate in the attic at the decking and then encased in sprayon foam insulation.


Here ya go! Courtesy of Jeff Remas.

Why do you have to prove it to a contractor with a photo?

“IRC 2006 M1501.1 Outdoor discharge. The air removed by every
mechanical exhaust system shall be discharged to the outdoors.
Air shall not be exhausted into an attic, soffit, ridge vent or
crawl space.”


“IRC 2006 M1506.2 Recirculation of air. Exhaust air from bathrooms
and toilet rooms shall not be recirculated within a residence or
to another dwelling unit and shall be exhausted directly to the
outdoors. Exhaust air from bathrooms and toilet rooms shall
not discharge into an attic, crawl space or other areas inside the

Thanks for the inputs. Got what I needed. I wrote it up as per IRC ref. but hardheaded builder and plumber.

Thanks again to all and have a Happy New One.


From my inspection agreement:

“INSPECTION DOES NOT INCLUDE – Negotiating issues with the builder/owner/contractor;…”

If you have to do that, you ought to charge for your time.

Some AHJ’s do not enforce that part of the C***. But I always write them up.

Actually the picture from Erby doesn’t begin to do a small leak justice. I have seen the entire inside of an attic coated with 1" of frost. Even the nail heads stuck out like spikes coated in ice. Spent hours crawling around with garbage bags and a scrapper removing the ice so that when it melted it would not come through the vapour barrier and drywall. The end vents of the gable were frozen over solid, and that was just from a leaky vent pipe.

I let slide going out the soffit or ridge vent. 95% of them around here do that and I’ve never seen any negative results from it. It’s when it goes nowhere and gets covered by insulation that problems happen.

Agree. Around here the local AHJ’s allow it. They require venting to the soffit or at least 18 inches above the insulation. I see a lot of these strapped to the trusses. (BTW, never found first hand damage from it. Ventilation is usually pretty good.) My own house is older and doesn’t even have exhaust tubing. BR vents blow directly into the insulation (of course I moved some of it to allow better air flow.) Not very efficient for heat/air loss, but with a 45 year old house, that’s to be expected.

I’m more concerned with dryer vents and kitchen vents. I have seen problems caused from both of these.

Gee Joe, you mean like the one going out the soffit in my picture?

I wonder if that soffit is actually ventilated? I bet not. I don’t see how that could happen on a newer home with well ventilated soffits.