I often wonder how someone that fails to follow a plan expects to be paid as if they did follow the plan, without good reason.

I consider electrical plans to be diagrammatic unless the plans included specific dimensions or a note with regard to the location of a fixture or fan. There is no dimension between the shower and the fan shown. That said, my concern would whether the fan's flow rate is adequate for the size of the room. Were the particular vent fans spec'd, and if so by whom?

Are you able physically to go up into the attic? You will find that that location was probably the easiest/quickest/cheapest for the sub that did the work. Your builder doesn't want to pay the sub to move it.

You should also make sure that it is properly vented through the roof.

Unless you specified the fan's make/model, you probably got the cheapest thing the hvac supplier carries.

Is this a custom build or a tract/production builder?

Another thing I noticed ... I think your bathroom doesn't have enough lighting, specially if your builder is going to use basic/cheap recessed lights with low lumens.

The distance between the shower and exhaust fan is about 9 1/2 feet from the shower head to the exhaust fan's current location over the vanities, with a 10 foot ceiling. Likely 110CFM fan. We have expressed concerns, but builder insists the fan is fine and refuses to move it to the location on the plans. This is a semi custom home.

If you follow Charles Ross Homes advice (which I totally agree with) let the builder know of your intent as soon as you can. The builder may find it easier to move the fan now rather than later and incur the expense.

Where does the fan exhaust to ? Location should recognize that being as close to the outside vent as possible helps to prevent moisture in the pipes from becoming water in the pipes. As the longer vent pipes cool down and moisture drops out. And where the excess moisture is vented to. You need it to be where it will be dispersed without dropping moisture on your house. Location to where the vented air goes to may be why the contractor, that installs and replaces regularly, knows better about the vent than the folks designing it. Not unusual.

Probably the most important is that the fan has an automatic humidistat in it. You can probably set it to run at the bottom of the moisture scale. Turning it on sooner.

Id suggest that you look at where it's exhausted to. It was suggested that it be installed through the roof. Do you really want another hole in your roof ? Although sometimes unavailable, because of the length of the vent pipe and the opportunity for condisation to cool and end up with water in it. Also I'd suggest that you use a galvanized metal pipe or abs pipe for the vent. Stay away from the accordian stuff. Too much wind turbulence. Straight wall pipes are better

I can't diagnose anything over the net. But trying to give you a reason why. That would make your venting more practical that hasn't been already mentioned

There is no code that addresses placement within the room, only that you have an exhaust fan.

Common sense tells me to locate the exhaust fan close to where the moist air is being generated, not to draw the moist air through the space.

There are rules to follow to meet the code. The exhaust fan needs to be located at least 3 feet from a window; otherwise, the moist air can circle back into the bathroom from an open window.

The OP's concern is the location of the exhaust fan with respect to the shower. The code speaks only to the location of the exhaust opening.

I think the code use to be if you had a window in the bathroom you were not required to have an exhaust fan; but that may have been before electricity.

Does it even vent to the outisde?

The exhaust fan usually has guidelines regarding placement in relation to the roof vent, e.g., how long a run, what, if any angle. It may be related to where the roof vent was placed.

I’m presuming roof vent since it’s new build in Florida.

Appreciate everyone's input. We are in the NW and this build is on the Florida coast. We are hiring and inspector. This was simply not placed correctly by the sub and builder is not wanting to cover the cost to correct.

Appreciate all the input. Lot's of good questions and feedback. We are in the PNW and this is a new build on the Florida gulf coast (retirement home). Vent was misplaced by subcontractor and builder does not want to move it ($). We will be getting an inspection.

So truly, make sure it vents to the great outdoors. Ask me how I know.

"Vent was misplaced by subcontractor and builder does not want to move it ($)."

Tell the builder I want to know why he does not want to do what is right?

RU asking for a second fan? Or to move the one installed? The Panasonic Whisper fans are about $200 each -- most of the cost for installing the fan is in the labor.

Having the exhaust fan over the vanities helps with defogging the mirrors.

I was told that having an exhaust fan in the ceiling above a shower would make the shower space colder -- sucks up the rising warm air,

"I was told that having an exhaust fan in the ceiling above a shower would make the shower space colder -- sucks up the rising warm air," The function of a bath vent fan is to exhaust moist air from the space. I've installed at least a hundred combination vent/fan lights directly over showers including three in my personal home. It has not been my experience that the shower is less comfortable with the fan operating, and it sure is nice not to have condensation dripping from the shower ceiling.

To avoid condensation and mildew on the bathroom ceiling, in addition to the exhaust fan, make sure that you choose a paint with a mildew / moisture-resistant coating, such as Benjamin Moore Aura Bath & Spa or Sherwin Williams Duration in a satin finish. (Made a big difference when I had my newly remodeled bathroom repainted.)

Sounds like the best solution will be to add the light/exhaust fan combo and leave the additional exhaust fan over the vanity.