Exhaust Fan Venting

4 years ago

last modified: 4 years ago

Hi my house was built in 2006 (PA). We have 3 full baths on the second floor. I replaced the Master bath exhaust fan a few years back. The line ran through the attic and out through a vent that was essentially in vinyl siding on the A frame peak side of the house so the vinyl extends higher then the walls in this area.. I went to replace the two other fans last night and found both lines run to the soffit and just disappear. These bathrooms are running around perpendicular sides of the house where the roof meets the walls and therefore there isn't an easy path out the side. From outside the house there is no exterior vent visible at these locations . The house is 3600 sq feet, the entire soffit is vented (there are holes in the soffit everywhere vs only certain areas). There is also a ridge vent the length of the house. The insulation in the attic is blown, there is pink styrofoam up from the soffit. There is no sign of mold in the attic. Curious if there is any scenario where this is ok. Its hard to get to that area of the roof, extremely low clearance, crawing in blown insulation etc. I tugged on the line a bit and noted its somewhat solid. Is there perhaps a downward-facing enclosure that doesn't go all the way through to the outside? It doesn't appear to be a scenario where they just have the pipe laying in the soffit. I could be wrong and they may just have it wire tied off though. Seems odd that this would have been done this way in new construction if its just blatantly wrong. Last night I installed the fans and ran new line, but when I got within a few feet I attached my new line to the old line. I know its not ideal but was my best option at that time. I am considering revisiting this but unsure what to do here.

Sort by:Oldest

Comments (7)

3onthetree
4 years ago
If you bought the house as new construction, I am surprised both that the exhaust duct terminations passed inspection and that they used rigid insulation for the insulation baffles in 2006. If you bought the house used, I am surprised the inspector did not notice, as that is 1 of 3 things they look for in the attic - water evidence, insulation thickness, and exhaust routing.

Fix it. It does not meet code, is not correct, and will bite you later when you sell.

IRC M1501.1 (paraphrased) Any exhaust air shall not be exhausted into an attic, soffit, or ridge vent.

IRC M1505.2 (paraphrased) Exhaust air from bathrooms shall not discharge into an attic or other areas inside the building.

IRC R303.6 (paraphrasing) Exhaust terminations shall be protected by a louver or grille and weatherproof.

It's not urgent, so you can take your time to wait out hot days, and move insulation around to access the areas. It would be better to run the ducts to the outside wall, soffit discharge (via a specific soffit termination cap) would be last resort. Do not combine ducts when you use room ceiling mounted fans.
Grant Albitz
Original Author
4 years ago
last modified: 4 years ago
thank you, the house was built in 2006, we purchased it in 2009, it wasn't noticed by inspection either time apparently. would you avoid a roof vent or are they fine? the one is only a few feet from the gable. the other would be about 30 feet from the gable, that would be the one I might want to do a roof vent at instead. EIther way we will use 6" line moving forward. The house is two stories so I think I will hire a pro, I would be more comfortable on the roof vs trying to drill a 6" hole through the gable on an extension ladder =)
Related Professionals
Cape Girardeau General Contractors · Murfreesboro General Contractors · Stamford General Contractors · Nashua General Contractors · Canton General Contractors · Washington Home Remodeling · Augusta Home Remodeling · Niles Home Remodeling · Brainerd Home Remodeling · Ithaca Home Remodeling · Modesto Home Remodeling · Elizabethtown Bathroom Remodelers · Columbia Bathroom Remodelers · Beaumont Bathroom Remodelers · Muskegon Bathroom Remodelers
3onthetree
4 years ago
Roof exhaust vents and soffit exhaust vents are comparable - 1 you have a roof penetration and possible snow issues, the other may look bad and have spring issues with the popular version.

Only use a 6" duct if the fan is sized for that. Most likely you need a 4" duct.
Grant Albitz
Original Author
4 years ago
thanks, i have the panasonic fans so they do have a 6 or 4" duct. I have a reputable roofer coming out to look at it, they will do either a gable or roof vent. they have done the roof replacements on most houses in our development. I would trust them with a roof vent. I believe the 1 fan is best suited for a roof vent to avoid a 25-30ft run to the gable.
vinmarks
4 years ago
Ours terminate in the soffit with a soffit termination. Haven't had any problems. They are only noticeable if your standing under them.
Grant Albitz
Original Author
4 years ago
mine do not exit the soffit, they must be laying on top if it in the attic.
PRO
Charles Ross Homes
4 years ago
Bath vent fans need to be exhausted to the exterior. One problem doing that though a vented soffit is the potential for moist exhaust air to be pulled into the attic through the continuous soffit vent. If you have continuous soffit vents, I recommend you block off the portion of the vent within a couple of feet of the exhaust termination.