Designing Kitchens and Bathrooms - Bathroom Vent Question

Hi,
We are doing a bit of a remodel and are wondering about placing the bathroom vent in a new location. The vent will be vented to an outside wall of the house. The question is if there are any requirements as to how the vent proceeds from the vent itself to the outside wall? That is, can the ducting just go straight to the wall, or does it need to have an upward or downward slope?
Thanks for any help!

It should always have an upward angle to it. Remember, air will go up, and rain water will go down, so you don't want it gathering in a corner of a downward, or level vent pipe. How far from your existing vent will the new installation be? Check with your local codes before installing the vent on the outside wall. It used to be commonplace, but now, if you live in an area with severe freeze problems, the moist air moving up the vent will freeze and refreeze on top of itself until it is totally occluded, unless it is properly insulated.

Thanks for the help Larry! We have now decided to keep the vent in the current location and just replace it with a better and more efficient unit. But, we noticed that the current ductwork seems to have a lot more length to it than what would seem to be needed. The current ducting leaves the vent, goes upward, then curves downward and then back upward to the outside vent. So, we thought about taking up some of this "slack" and shortening the length of the ductwork.

A vent that goes down and then up will retain moisture and freeze, as Larry stated. The ideal situation is the shortest and straightest run of duct to the outside. My only disagreement with Larry is that, in my opinion, a duct going out the sidewall should slope downwards away from the fan to the outside so that moisture will run out of the duct and not back into the fan unit. In no case do you want to trap water in the duct. You may also want to consider insulating the duct to prevent freezing and use an endcap with movable louvers to prevent wind from blowing into the duct. A larger CFM fan is also a good idea. It will give more "push" to the moisture. The fan should be run for 20 to 30 minutes after using the shower. Good luck.

Thank you, again, Larry and Majak! You both were very helpful.

I misunderstood the OP. I thought you were talking about a drain vent, not a fan vent. The OP didn't specify. Sorry for not clarifying that.