Sanity Check on # of Toilets on 3" Drain

[AlaskanInTexas]

New guy here - an overly ambitious DIY fellow.

I am doing a major remodel, and am going from 4 full baths to 4 1/2 baths. I have an existing 3" house drain, which serves 4 toilets. After the remodel, that drain will need to serve 5 toilets.

I have done the calculations and I am within the DFU limits for a 3" drain. I also see no prohibition in the 2015 IPC (our jurisdiction) to the number of toilets on a drain. But I keep reading references on the internet to limitations (some saying 2, some 3, some 4..., some saying 3 if they enter within 15' etc.). I simply cannot find these in Chapter 7 of the IPC and am wondering if these are just relics of the past, or if I am missing something.

 

[frodo]

not enough information
need to know what all is being connected to the sewer
number of sinks, washer, kitchen sink tubs and showers

 

[AlaskanInTexas]

Here is the information:

4 bathroom units, plus an extra lavatory and tub in one of them - 23 DFU
1/2 bath - 4 DFU
Automatic clothes washer + sink - 4 DFU
Dishwasher + kitchen sink - 4 DFU

Total DFU's 35
Code limit: 36 for horizontal branch; 42 for main drain

It looks like I am okay for DFUs, but I am worried about references to limitations on the # of toilets on a 3" drain apart from the DFU limitations.

 

[AlaskanInTexas]

Just checking back in to see if anyone is aware of a specific limit to the number of toilets on a 3" drain line (besides restrictions based on DFUs for the building as whole). I have scoured the 2015 IPC, but cannot find any prohibition. But I see uncited references all over the Internet to a code limitation on the number of toilets on a 3" line - just trying to find out if I am missing something in the code.

 

[AlaskanInTexas]

I think I have solved my own question. The 1997 IPC had a limit of 3 water closets on a 3" drain, but that limit has been removed for all subsequent versions of the code. It sounds like everything I am hearing is either dated or from folks who are still living in the 90's.