Thru-Wall exhaust on window header?


I am trying to add a thru-wall fan in my 1st floor bathroom. The bathroom is 59 inches wall to wall. There is a window of 41 inches. I want to add the fan above the window, but i found a window header on the top. Either side of the header cannot be used as the maximum radius that can be drilled is less than 6 inches. My fan needs a 6 3/8th of hole and further the upper cover is 8 inches. Can i drill a hole on the window load bearing header? Ceiling to window start is 13 inches. Further I cannot add a ceiling exhaust fan as I have a 2nd floor above and no attic access. I have attached the image with details

q thru wall exhaust on window header
  12 answers
  • Dee Dee on Aug 22, 2020

    I think you need to contact a contractor to find out if your housing codes allow this.

  • Lifestyles Homes Lifestyles Homes on Aug 22, 2020

    No, you can’t drill into your header. It’s a mandatory structural framing member.

    You can go through the ceiling joist space and drill a hole in the rim joist.

    You must return that fan and buy a ceiling mounted one that only requires either a 3.5” or 4” hole and the flex hose w/ flap cover on the outside.

  • I would not touch the header without checking with a licensed contractor first. Usually that's a bad idea.

  • William William on Aug 22, 2020

    Nope. The header supports the weight of upper floor. Cutting a hole into it would compromise it's weight bearing capacity. Your only solution is getting a ceiling fan. Cut into the ceiling drywall where you want the fan. Inspect the ceiling joists. Then cut a out the drywall at the outside wall where the exhaust would exit. Save the cut outs so you can use them to patch the ceiling. Cut the required 4" hole for the exhaust vent cap to the outside.

  • Kmdreamer Kmdreamer on Aug 22, 2020

    You will have to drill a whole through all the wood .that will be about putting it in the wall

  • DiySri DiySri on Aug 23, 2020

    Thanks all for the quick answers. It helped me a lot. I will return the fan and try a ceiling fan.

  • Ken Erickson Ken Erickson on Aug 23, 2020

    Another option is to open the window a bit. There are also fan units that can fit between the sill and bottom of the window (for double hung windows). Might be other options for sliding windows.

  • DiySri DiySri on Aug 23, 2020

    I will check on Amazon what model fits on the window, that will help as well.

  • Annie Annie on Aug 25, 2020

    Drilling a hole that size through a header would defeat the purpose of the header. It possibly could be done if you could add another member to the header and / or if the header was LVL instead of dimension lumber. Also look at what is sitting on the wall above the window. If there are floor or cieling joists??

  • Agnes Chrzanowska Agnes Chrzanowska on Aug 31, 2020

    I would ask a professionals about that project to make sure all is done right

  • No you cannot. This is a job for a pro.

  • DiySri DiySri on Sep 03, 2020

    Thanks all for the answers. I bought a simple window fan and installed it. The model is Holmes 6 inch reversable fan. It fits well and is working well. Thanks for all the suggestions.