3rd floor bathroom in 1924 house

[AnthonyL]

I own an old 1924 2-family in Providence. I have decided I wish to add a half bath in the attic space (some time down the road I plan to put a nantucket style dormer in this area but want the toilet, sink now) As far as I can tell there is no dry venting in the house? Is it possible for me to add a toilet and a sink on the 3rd floor without creating problems with the bathrooms on the 1st and 2nd floors?

My second issue is how to dry vent the the sink? Since the area I wish to add is primarily eave space, how do I deal with appropriate height of the vent line to tie into the existing stack? Would an AAV be acceptable for the sink?

 

[Jimbo]

Don't know your code, but certainly under the UPC, you cannot drain a 3rd floor bathroom group into the vent stack which comes up from the 2nd floor.

Some codes are lenient about AAV's. Other places allow one only it there is no other possibile way to do it.......and there is ALWAYS a way to do it.....not necessarily cheap or easy!

 

[Sponsor]

 

[TorontoTim]

I think the drain is going to be a bigger challenge than the vents.

Can you run a new drain line down to the same level as any drains on the 2nd floor?

 

[AnthonyL]

Yikes!

So, in that case there must be a vent line connection somewhere between the 1st and 2nd floor for those two baths? Or, is it possible they were not concerned with that in 1924???

I guess my idea for a third floor bath will be virtually impossible until I can do some major demo work on the second floor accessing those fixtures and adding sufficient venting?

 

[AnthonyL]

Taysan:

That gave me a little bit of an idea but Im not sure. Its becoming clear I will need to do some demo work on the second floor to access the lines down there. The 3rd floor space is 100% accessible. It seems I would either:

(a) tie the drain lines into the existing 2nd floor lines without disturbing the vent line from 2nd floor up

(b) tie the drain lines into the existing pipe and rework the vent from the 2nd floor up

I think (a) makes most sense as the vent from the 2nd floor up is still CI. Unfortunately, I cant demo the second floor for quite a long time as it is currently in use