Bathroom Exhaust Fan Ducting

Discussion in 'Shower & Bathtub Forum & Blog' started by Joe Weekley, Jun 9, 2016.

  1. Joe Weekley

    Joe Weekley New Member

    Mar 16, 2016
    Huntington, WV
    We are in the planning stages of a bathroom remodel and I had a question on ducting the new exhaust fan.

    The existing fan was vented to the attic with no duct and as such we don't use it. I'll be installing a new Utilitech 7131-01 from Lowe's and have a question on the best duct route.

    I can 90 out of the fan and straight up 2 feet and go through the roof or 90 out of the fan and go about 10 feet to the gable end. I've read that it is preferable to vent the fan through a gable end instead of up and through the roof, but the house is a brick, side-gabled colonial and I'd prefer not to have to drill a 4" hole through the block and brick. If it matters, the roof exit would be on the North side of the roof and the gable exit would be on the East side. Where I am in WV, my roof snow depth is rarely more than an inch or two and doesn't last more than a few days/week at most.

    Would venting through the roof be OK and if so, what would be the best roof vent to use?

    Thanks in advance for any advice.
  2. Smooky

    Smooky In the Trades

    Apr 4, 2011
    North Carolina
    I would rent Core Drill Rig and drill through the brick. It would probably cost around $75 for 4 hours. Years ago I bought a small diameter star drill that was about 18 inches long for the same purpose. I drilled a center hole from the inside and then went outside and marked a circle on the brick. I used the star drill around the circle and then chiseled it out. It made a nice hole. You could do the same thing with a masonry bit and a hammer drill.

    I have one on the roof similar to this for the bath exhaust:

    I have inline fantech exhaust for the bath room. It is very quiet:

    The kitchen exhaust vents out the gable end and if I had it to do over I would vent the bath exhaust out the gable end as well.

    I have one for my dryer like this. It is nice and heavy duty:
    Last edited: Jun 9, 2016
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Res_Daylighting_Hero2.jpg I don't use my fan all that much in the winter since adding moisture to the house often helps a bit! Often have lots more snow on the roof than you, though. My vent is a low-profile unit with a flapper that opens when the fan is on, and closes to help prevent both heat escaping and cold air from coming in. I bought it at Grainger, long time ago. FWIW, there's also a second damper in the duct down lower. Mine needs to rise about 7' to get to the roof. You'll want to insulate the duct well.

    One thing that I did that has proven to be a godsend, is when I remodeled, I put in a SolaTube, tubular skylight with a light and fan option. My bathroom does not have a window, and with the tubular skylight in full sun, brings in about the equivalent of a 300W lightbulb of free light. Well worth the effort, but it now takes two holes in the roof - one for the light collector and the second for the exhaust. Of those available, I think that brand had both the best light color and light transmission efficiency. Vent_Kit_Large_0.png
  5. lanachurner

    lanachurner Member

    Mar 25, 2016
    I would just go through the riof.
    It's sure a lot easier than boring through brick.
    We get plenty of snow here and never have a problem with roof vents.
    I always use 4" insulated flex duct for the run through the attic.
    As said, it is important to insulate it as all that hot steamy air will condense in a non insulated duct and give you a drippy fan in your bathroom.
  6. Joe Weekley

    Joe Weekley New Member

    Mar 16, 2016
    Huntington, WV
    Thanks for the suggestions everybody.

    I think I'll go through the roof since it's such a straight shot and I won't have to go through the brick. I'll definitely go with insulated duct as well.

    smooky: thanks for the links!

    jadnashua: that looks awesome! I'll show the wife and see what she thinks.
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