Single to Double Wall Switch Wiring

Hello all,
I'm adding an exhaust fan (powered by the existing lighting circuit) to a bathroom and want to change the single light switch to double switches for fan and light. Is there any reason not to replace the existing 14/2 cable running to the switch box with a 14/3 to control light and fan (code/safety/difficulty). It would be a lot easier to draw a single replacement cable up through the existing holes/cavity than running a second 14/2 down to the new double-gang box. (The wall switch is on the outside wall of a sauna, so the wall is stuffed with insulation.) Thanks for any advice.
Denny
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Dennis Straussfogel wrote:

That is fine. It would commonly be wired that way from the beginning.
--
Joseph Meehan

Dia duit
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
The only difficulty would be if the existing cable is stapled, and can't be pulled out. If the fan is over a tub, it must be GFCI protected

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Right, didn't think of it being stapled (ugh!)--I'll find out today. (Not over the tub/shower so no GFCI required.) Thanks to you and Joe M. for your replies.
Denny
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.