I have a basement bathroom basically smack dab in the middle of the basement. The joists run from front-to-back of house. So going out either side is not an option. Going out the front is not an option because I will hit a slab porch. So my ways out are back or up.
Going up entails going 4 feet doing a 90 up and then out the attic. Going out the back – there is already duct work in the joist run the fan is on. It is an unfinished laundry/storage room and would be about 15 feet total.
So I guess my options are go under duct work (sticking below joist a couple inches but still 7 feet up) and out back, do a couple 90s to move to joist over (going under joist temporarily then back up) and out the back, or going 5 feet over then 90 through the main floor then out the attic.
The attic would be a long run – 5 feet, plus 10 feet to get to attic, plus 15 feet to get to soffit. To the back of the house would be 15-20 feet total.
Also I have thought about buying one of those no vent out machines that slowly releases humidity to laundry area. The basement/house is dry and could use moisture. Anything is in play!
Best Answer
Is your furnace in the basement? Is it forced air?
If so, the main supply run probably goes UNDER the joists... Attach your bath fan run alongside it.