I wanted to clarify my question a little. I am between 2 companies they differ on the way my plumbing should be vented but neither can seem to give me an educated explanation of why? My bathroom is 6.5' x 9' if that makes a difference. I am looking for some opinions of which I should go with and why.
Thanks again

A two year-old house would have everything in place to hook up the fixtures incluging venting. The rough-in, to pass inspection, would be complete and up to code. At the rough-in stage the inspector would not know if the basement would be finished at that time or later.

I would put an automatic air vent in the lavitory cabinet or high in a vent box if your installing a pedistall (2" stub) or if possible tie it into another vent on your main floor (42" above main floor).
The 2" stub is a wet vent for your tub and lavitory. Witch is the same way I intall a basement bath rough-in. I don't understand why they are not explaining this to you.

I have a similar situation in a 2002 Michigan house we recently bought from the "professional" builder who was living in it. (If you're keeping score, this is a second house from my '72 ranch.) The unfinished basement's floor has rough-in drains for a full bath and for a kitchen sink. If there's any venting, it's well concealed under the concrete. Two stacks coming down from above are also used to drain the kitchen, laundry, and baths from above. There's nothing else visible that could be vents.

Once projects back at the ranch are finished (a few months to go), we'll start improving the new house.

Questions that come to mind: What would the next required inspection be if the basement rough-in was already approved? Should the rough-in for the basement have included the supply lines? Or are the drains and supply lines treated spearately? Do the inspection authorities typically keep sufficiently detailed records to know that the rough-in was approved in 2002 when I'm finishing the work in 2008?

Callen33's question lacks sufficient data to give a definitive answer. First we need to determine if this bathroom roughin is actually connected to a drain or a vented drain. In order to determine if this is a vented drain we would need to begin by locating the point where the house sewer line enters the structure.

Municipal sewers typically run in an easment beside the street so the obvious point of entry would be at the front of the structure, however is some rare instances a municipal sewer could also be located in an easement behind or beside the structure. (This is especially common for structures built on the corner of an intersection). If the structure is served by a septic tank the point of entry would generally be through the wall on the side towards the septic tank location.

Code requires a "Main Cleanout" at the junction of the "house sewer"(the underground line from the municipal main or septic tank to the structure) and the "house main drain"(The main drain inside the strucuture). The main cleanout is required to be placed within 3' of the point of entry. Begin by locating the Main Cleanout.

Now we must consider how the DWV system is installed on the ground floor. In some instances the main drain may continue through the basement floor to a riser that goes up to the main floor. Code requires all fixtures attached to that riser to be vented so the riser is also vented and any portion of the drain line under the basement floor downstream of that riser would be classified as a "Vented Drain. If the basement bathroom location is located between the riser and the main cleanout the basement bathroom is most likely "Wet Vented" from the Vented drain however, if the basement bathroom location is upstream from the combination waste & vent riser it would be considered a Drain, but not a vented drain and the allowable distance from the waste & Vent stack to the bathroom fixture location would be limited to the permissible length of an unvented Fixture Arm. The International Residential Code allows a 4" line to run 16' while the Uniform Plumbing Code limits a 4" or greater line to 10'.

Code requires all drain lines to have a cleanout on the upstream end. Code also requires a watercloset to be on the end of a line and a watercloset can be lifted permitting unobstructed access to the line so we commonly use the watercloset at the cleanout.

If you are under the Uniform Plumbing Code you could measure the straight line distance from the waste & Vent stack to the water closet and if that distance is 10' or less you will not be required any additional venting for the basement fixtures.

The IRC is not nearly as restrictive as the UPC but because of this the IRC can be confusing. Under the IRC if a watercloset is the only fixture served by the drain line it may run an indefinite distance from the watercloset to the vent however at some point the lavatory drain and the tub/shower drain are most likely also tied into the watercloset drain line. In this case drop a chalk line from the waste & vent stack to the watercloset. That will indicate where the 4" line runs. Under the IRC we can compute the allowable lenght of an unvented waste arm by dividing the diameter of the line by the required pitch. Code requires the Tub/shower to have an 1-1/2" drain line but code will permit increasing the line size by one nominal trade size which explains why your tub/shower drain line is a 2" line instead of an 1-1/2" line. Lines under 3" dia. require a 1/4" per foot pitch so the maximum length of a 2" fixture arm is 2" / .25" = 8' from the trap weir to the vent.

Now begin at the waste & vent stack and measure 16' towards the watercloset. Now measure 8' from the tub/shower stub out to the water closet line. If the distance from the Tub/shower to the watercloset line is 8' or less and if the point of intersection is within the first 16' of the water closet line when measured from the waste & vent stack no additional venting is required for the tub/shower.

It was subsequently stated that if the roughin passed inspection during construction no further venting would be required but this is not correct. During original construction the roughin(lines under the floor) would have been inspected and approved however vents are not installed until the "Stackout phase" and since the stackout for fuure bathroom was never completed the vents would not be present for inspection thus we have to use the above methods to determine if additional venting is required.

Now in regards to Michgeo's question about supply lines. Drain lines operate solely be gravity flow therefore by necessity they must be lower than the fixtures they serve which means any fixture drain in a basement must run under the floor. Supply lines however are not limited to gravity flow so they would typically be run through the floor joists in the basement ceiling and drop down the the point of demand.

To answer Lazypup I am on city sewer and water, the main cleanout is in the front of the house facing the street. As far as all the technical jargon I am not well versed so I am not sure what (DWV, Watercloset) is.

I was able to track down the company that originally plumbed my house during construction. The warranty guy said in WI the code is different and they are not required to run a vertical vent for everything. All that needs to be done is tee in the sink all the venting is already there. He said I should have one vent stack running through the roof in which controls venting for the whole system. This vent he is talking about is 2". Now I will have 3 full baths, the kitchen sink, and a dishwasher once the basement bath is complete.

My new question is whether or not this is enough venting and if the bathroom gets tied into the vent would this cause a problem with all the plumbing?

Thanks

I didn't fully answer Lazypup the roughed in plumbing is located about 3 -5 ' from one of the main stacks. I have 2 due to the 2 baths upstairs one in front and one in back. the one in the back is the main vent stack.

Hope that helps

Your fixtures are close enough to a vent stack to adequately wet vent so you will not require any additional venting for your basement bathroom installation.

I would like to thank everyone for your responces, Lazypup you are a great resource of information thank you!