Basement Half Bathroom install

Hi all,
First post here, so be gentle.
I am installing a half bathroom in the basement of my 60 year old house. My problem is I have no vent (other than the 4" main stack vent) in the basement that I can access. I cant access the upper portion of the stack vent in the attic to run a new vent down to the basement, as it is all enclosed and it would be a nightmare to cut a new hole in the roof and run a vent to the basement.
Attached is what I am proposing to do in red. Basically, I want to use the main vent stack, as the vent for the basement bathroom sink, even though the 1st floor bathroom uses this part of the pipe to dispose of waste.
Will this work? If not, why.
Thanks for any help guys.

You cannot connect any fixture's vent to another fixture's drain pipe, no matter how large the pipe might be.

Any house can have a new vent installed. A bath only requires one 1-1/2" or 2" vent pipe which can be installed without opening the walls in the 1st floor. In a worst case scenario, such as a multi-story brownstone with brick and plaster, the pipe can be hidden in a chase up the exterior of the building.

There is more than one way to plumb a building, but the minimum requirement is to meet the standards set by the plumbing codes. Anything less is not worth doing at all.

It can be done. It may be it is beyond your ability to DIY, but a pro can do it.

Gary Swart said:

It can be done. It may be it is beyond your ability to DIY, but a pro can do it.

Click to expand...

Thanks for the advice guys.
Would it be legal to run the vent pipe through the sill plate and up the exterior of the house to the roof (or at least 15' off the ground above where smells would be an issue)? I live in New York, where freezing could be an issue.
Thanks again.

A vertical vent does not hold water, but can can build ice due to condensation. If I had to do what you are suggesting, the pipe would be in a chase that is insulated and heated using the building's HVAC.