I am planning to install a new bathroom in my basement in PA. I replaced my outside sewer line (installed french drains and shattered all teracotta pipes)to 4" ABS it goes under my foundation and hits a wye on the inside ( I dug hole in concrete). The one side picks up my basement floor drains and my washer. The other side I capped to add a new bathroom. My upstairs bathrooms and kitchen are on a seperate line that goes out and wyes into the same 4" abs that was newly installed.

I am going to partition off basement and cut runs in concrete to run the pipes.

My question I want to install a toilet, fiberglass shower stall and a sink and run into this capped wye. How will I vent this? I cannot easily access any existing vents.

If it is a single story house, it wouldn't be too bad of a job to cut a hole into a wall cavity top and bottom and run a vent pipe up through it into the attic and then through the roof. Choosing an interior wall would avoid the complication of insulation. A 2 story house would mean selecting a wall with another wall above it on the second story. It would also mean knocking a hole in the drywall for access to go through the second floor. Check to make sure the wall cavity isn't being used for heating or have wires in it.

I have a cape cod built in the early 50's both upper floors are finished, if go through an interior wall I will end up under the floor on the top floor. If I go up an exterior wall I will end up right behind the gutters in the eaves which is tight.

There was an existing toilet and a rough block shower stall in the basement,
Both of these were previously un-vented.They tied into the floor and washer drain. Neither had a problem with draining. I disconnected these when I replaced the main sewer line.

I installed a wye and capped one side off just under the slab on the interior of my basement because I knew I would be installing this new bath in the basement. I will note there is a breather line and a trap located between my house and city sewer line.

Can I:
1) use some sort of flapper vent on the shower and sink and not worry about the toilet.
2) run up to the top coarse of brick and penetrate outside for venting the basement bath only?

I hope there is some other alternative than going to the roof. Any other suggestions? As I stated I am in Pennsylvania.

2 sounds better to me than 1. Keep it away fropm any windows. I guess another alternative would be to identify where an existing vet is and tie into it. Tom should be dropping in, and he may have some better ideas. He knows his stuff.

"Tom should be dropping in, and he may have some better ideas. He knows his stuff."
Thanks Labman, I may just have his answer. A Studor Mechanical Spring Loaded Vent. The factories a few miles north of me and I'm familiar with the product. Check it out at; http://www.studor.com/homeowners.htm

This vent will set on top of the drainage tee that picks up the lavatory.
Here's how it goes. Extend the 4" over and pick up the toilet. On the way and downstream from the toilet install a 4 X 2" fitting aimed at the lavatory use a 2" short sweep elbo and stub the lav out at 18" from the finished floor to the center of a 2" drainage tee, the Studor Vent will top off the tee. Some where between the 4" line to the toilet and the short sweep install a 2" fitting aimed at the spot the trap for the shower will go.
The lavatory will be vented and the toilet and shower will wet vent through the lav drain. More questions? I'm as close as a click. Cheers, Tom