On May 6, 1:26*am, "MiamiCuse" wrote:
I am trying to size my bathroom exhaust fan. *Most sizing chart says to use
the SQFT size and multiply by 1.1 to get the CFM if ceiling is standard 8'..
So for a 10x10 bath = 100 SF it would be 110 CFM.

However when you use finish using your bath typically you have the fan on
and the bathroom door open right? *So it's drawing the air in the bath PLUS
the air from outside the bath. *Would it be a good rule of thumb to
overshoot the 1.1 multiplier? *or that already have a safety factor
built-in?

Thanks,

MC

Most manufacturers assume that you'll be drawing air from room or a
window anyaway, so its built in to the calculations.
It also depends how you duct it, and how far away the fan has to push
the air to the outside. Rigid duct is a little better than flex duct,
but don't go out of your way if the run is short.
For a 10X10 room, 100CFM is fine, but like others said noise is a
factor, so look into quiet fans like Panasonic