I am completely renovating a bathroom in a 1973 mobile home. There is no vent stack from any of the toilet, tub or lav fixtures. I plan to install the "Studor" vent in the wall. Can I use one vent for two fixtures or does each fixture need it's own vent?

"Can I use one vent for two fixtures or does each fixture need it's own vent?"

Every fixture that has a trap must have its own vent unless the two fixtures are combined into one drain line after the traps. Then you may put a Studor vent on the drain line downstream from the traps. Good luck, Tom