Perhaps your looking in the wrong direction....LOL Far too often when the exhaust fan fails to eliminate the steam ppl instantly think the fan is not big enough, but that may not be the problem at all. Nature abhors a vacuum therefore no matter how big the fan and duct system are it will not discharge air from the room unless there is a provision for an equal amount of air to enter the room. Typically the only provision for air to enter the room is the gap under the door and that may not be sufficient to your need. Try an experiment. Begin with the door closed in the normal manner and turn one both the fan and your showers. Once the steam begins to build up open the door slightly to allow a bit more air to enter around the door. If that seems to solve the problem then the permanent solution would be to cut a bit more off the bottom of the door or install a transfer air duct through the wall to an adjacent room.

Is that your only bathroom? People do it. Maybe it's more important your co-worker knows what's involved in being a GC than knowing you? I don't know. When I started I knew nothing and had no experience, so I knew no way. Having gone through two bathrooms, if I had the time I might consider it but I'd spend so much time doing research I'd probably never complete it. Are you moving pipes? If not, you might be better off with a skilled, insured expensive handy man who would relish your input. Someone who loves to learn but is so swamped with work, they'd be glad to have you figure out the best grout, water proofing system, exhaust fan requiremens, etc. Those types do it all themselves so you'd only have to find the one right fit instead of asking the GC what type of grout his tile guy uses as that usually ticks them off and sets up red flag for them that you're going to be a PITA. Maybe that would be a better fit if your primary concern is that it's done with best practices? Maybe being your own GC is the best fit if you have enough experience to pull it off and your focus is best practices, exquisite craftsmanship and your budget allows for that?

Megan Morrill-Denton, several people here offering a lot of good points. Since you've cleaned your ducting, I can't think of any other ways to improve drying, and you've mentioned you really don't have any length to the outside except 10" - though if you've got the 'corrugated' type ducting, straight galvanized might help a little. You've also mentioned that the ducting to the dryer isn't kinked... so I've no further help on that other than to suggest you use electric foil tape when you connect it to the dryer - we only had the clamp initially and it did a poor job of holding the duct leak-free to the dryer. You mentioned a cold floor... we had that issue - the whole room actually. When we pulled out our old dryer, I noted cold air flooding from the corrugated duct coming out from the wall (actually placed a baggie over it, taped it close to keep cold air from flooding into the room - the baggie stayed puffed with air until we replaced the outdoor vent cap). I can't really speak for the Heartland style outdoor vent other than to say once we installed that, I noticed the baggie no longer inflated with air from the outside. That was a plus for us. We previously had the slat-style outdoor vent. As dadoes mentioned, it needs painted if you don't want it to stick out like a sore thumb (it's rather big), and I used a can of plastic approved Krylon Fusion paint from Lowe's for ours. Keeping any part of your ducting and vent cap clear of lint is important, and reduces fire hazards - sounds like you are doing this. Good luck on your situation.

We've had w/d in the master bath for 22 years. We love it. No negative issues. We do have an exhaust fan in the bathroom. The moisture in the room is vented outside and has not corroded our appliances. This is an add-on master bath we built and had all inspections done and passed. I don't remember it being a hurdle to clear, but maybe the building codes have changed since then. We have exhaust to outside dryer. We used to have Fridgeidaire/Electolux dryer in place, no heat added to the room. Now we have Hotpoint/GE dryer and it does add heat to the room. This is welcome in the winter, but in the summer it can make a warm room a bit hot as suezebell mentions. (we don't have A/C) The heat issue probably depends on the dryer itself. All the dryers I've had in my life have added heat to a room, except for the Fridgedaire/Electrolux model.