Basement drains in a modular

I have to plumb the basement drains for a modular. We use the 2006 IRC code book. The owner wants drains plumbed for a future bathroom in the basement. Since 2006 IRC says no wet venting between floors, I have to get a vent from the basement up through the roof. Are there any ways around that? Do new modular home companies allow for a vent for basements, if not, why, they are UL listed, correct? I guess this might be something modular home builders need to be made aware of if there is going to be a basement.

mark

Thanks I shall have to tell the owner to order that.

mark