Vent question

HI,
I am adding a full bath, single story house. The main sewer line HORIZONTAL (4") is under the room (is it still called a "stack" if its horz.??) and serves 2 full baths upstream. Those bathrooms are each vented (two-2" vents). In the new bath insead of venting each appliance (shower-toilet-sink), can I run drains directly to the 4" "stack (within the required trap arm length) and run a sinlge 2" vent off of the 4" stack to service the new bathroom??
If this works, does the new single vent off the 4" sewer line need also to be within the required arm length (or can I take additional arm lenght when it enters the larger 4" line)

THANKS!
Kevin

vents

The vertical lines are "stacks". NO, you cannot connect directly to ANY pipe being used as a drain for upstream fixtures, NOR can you connect to any stack being used as a vent. Sort of limits your options doesn't it. The distance from the main line is irrelevent as far as vents and their requirements are concerned. EVERY fixture needs a vent of some type, and a "vent" pipe in the "general area" is seldom a vent for anything.

well what that guy said is a lot different than here in Georgia. You can connect to that line in Georgia as long as you have enough dfu's available on that 4'' line. as far as the vent question you would definitely have to vent the lav. in Georgia i think it is like 16 feet you can run a branch line off the trunk line before venting.

The 4" horizontal line may be used depending on what else is currently using it. You will need a new vent through the roof.