GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Wall-mounted bath fan in an uninsulated brick wall

user-982243 | Posted in Mechanicals on

Hi, I live in a 100 year-old row home in Montreal, (where it can easily go down to -20 in the winter). The walls are double brick with no insulation, luckily most walls are abutted by an adjoining home. There are a few exposed walls in bump-outs though. One of those walls is our master bathroom, which has no fan. I want to install one.

I understand that ideally it would go through the roof. However, we have a flat roof with about two feet of attic space, and no access to the attic. (Frankly, what’s up in that two-foot space is a total mystery.) In a few years time we will have to re-do the roof, but until then I have no interest in messing with it by making a giant hole through it.

So, I’m thinking of installing a wall-mount fan. My question is, will this just be a massive source of heat loss due to the fact that there will only be about six inches of duct between the inlet and outlet? I can’t imagine a bath fan damper being a great insulator. Is there another approach we should consider?

Thanks in advance for any help!

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.

Replies

  1. GBA Editor
    Martin Holladay | | #1

    Sean,
    Wall-mounted exhaust fans do, indeed, have more customer complaints about air leakage than ceiling-mounted fans that are vented through the roof.

    I don't think the fact that your brick wall is uninsulated is relevant -- it will not change the air leakage situation for better or worse.

    Whether or not the air leakage will irk you depends on many factors: the prevailing winds, whether the wall is sheltered, the strength of your heating system, and your personal sensitivities.

  2. user-982243 | | #2

    Thanks Martin. I guess I confused the issue by mentioning the lack of insulation... I was thinking the short length of ductwork would be the biggest issue, because any glancing wind will have a more direct route into the home, (ignoring the benefit of a duct flap). But as you said, that will be an issue, but how much of an issue depends on a lot of things. Thanks very much for your feedback.

Log in or create an account to post an answer.

Community

Recent Questions and Replies

  • |
  • |
  • |
  • |