I have a 4x6 upstairs bathroom - just sink and toilet - that has a wall exhaust fan. Problem is I can see some daylight when I look out the fan and in summer and winter hot/cold air blows right in the house (along with smoke from neighbors fireplaces). I either need a wall fan that locks tight or I need to put some sort of very tiny window in that spot (a tiny window would be wonderful because the bathroom in very dark and gets mold easily). I'm not sure if I can install a glass block window instead of a fan (those are the only ones I can think of that would fit in the area I have to work with). Upstairs addition is a 1/4 addition so I don't have much room between the roof of the addition and the main roof. The bathroom needs to be updated anyway since it hasn't been touched since about 1980....
By the way my main bath is about the same size with a whirlpool tub (original owners put it in) that I would love to get rid of but don't have the money to update. Also would LOVE to get rid of my tile floor in that bath - I hate tile! Give my vinyl anyday - much easier to keep looking clean