Hi

I am replacing my basement concrete floor (old floor was in bad shape) and want to add a basement toilet. The new floor will be at the same level as the old floor. The main 4" cast iron drain pipe runs under the floor and exits to a city sewer system. I measured 6" from the top of the pipe to the top of the floor. Also, the new toilet will be within a couple of feet of the main drain pipe. While open, I will replace the old cast iron with plastic. My question is do I need any minimum vertical drop to make the toilet work properly, other than sloping the pipe down 1/4 inch per foot (1/2 inch!). Also do I just tap into the main drain with a Y tee?

Thanks

Hi Mark

Thanks for the reply. Just to clarify, the 4" cast iron drain pipe under the floor that I wish to tap into continues under the floor for approx 20 feet (with a 1/4 inch per foot slope upward)then sweeps through a 90 degree turn to a vertical stack. This stack continues up two stories and through the roof where it is vented to the outside. Another toilet and other kitchen/bath drains empty into this vertical stack. Do I still require another vent for the basement toilet, or is the main stack vent enough?

Thanks

Ron

Hi Ron...

You'll cut into the cast iron and install a NO-HUB CAST IRON WYE FITTING with shielded clamps as you suspected. You'll also need to VENT the toilet. Here, I'd recommend that you also install a 2" sink drain and 2" vent. The 2" vent for the sink can act as a WET VENT for the toilet if installed correctly...;) You cannot just install a toilet without some kind of vent.

1/4" per foot of pipe is perfect.

Let us know if you want to discuss more... OK?

Mark


Hi Ron...

I only got part of your message. Post in the ANSWER THIS QUESTION box below to reply to me.

Back to you...

Hi Mark

Thanks for the reply. Just to clarify, the 4" cast iron drain pipe under the floor that I wish to tap into continues under the floor for approx 20 feet (with a 1/4 inch per foot slope upward)then sweeps through a 90 degree turn to a vertica

Sorry Mark, I am still figuring out this site and accidentally clicked on the Disagree button!! :(

Ron

Hi Mark

Thanks for the reply. Just to clarify, the 4" cast iron drain pipe under the floor that I wish to tap into continues under the concrete basement floor for approx 20 feet (with a 1/4 inch per foot slope upward)then sweeps thru a 90 degree turn to a vertical stack. Another bathroom and a kitcken on a floor above empty and vent into the stack. The stack continues up thru the roof and open ends as a 4" vent. I can locate the new basement bathroom anywhere along the buried section of pipe. Does this impact the venting requirement? If I do need still a vent, what does the combined sink / toilet wet vent look like?

Ron

You still need a vent, Ron. All fixtures need a vent in some manner or another... ;)

Here, you can take the sink drain and vent and use the vent to wet vent the toilet... see image below... the 3" would connect into the cast iron via a 4"x3" cast iron wye fitting. You would transition to PVC using a cast iron x PVC shielded clamp. The 2" vent can connect to a 2" or larger vent upstairs or it can exit the roof as drawn below. When you come out of the concrete floor with the 2" drain install a 2" cleanout under the vanity if possible.

Finally, you could also install a STUDOR vent (also called an AAV...see image) if they are allowed in your area. Here, you would install the AAV in the vanity sink base so it could be changed if the vent failed.

Back to you...

Hi Mark

Thanks for the reply. I will look into the AAV to find out if they are permitted here, otherwise the vent install looks straightforward.
I have a second question. My house currently has no perimeter drainage "big O" or weeping tiles. I will likely add these. How do I hook the perimeter drain into the main drain? Is it the same as a toilet? Does it need a trap and vent? Are there backflow issues?

Thanks
Ron

Hi Ron...

It is illegal everywhere nowadays that I know of to tie the perimeter drains or even a sump pump into the sewer system in any way.

Here, you should run the perimeter drain pipe into a sump pump pit and then pump the water up and out of the house with an 1.5" discharge sump pump (I recommend ZOELLER PUMP). You could run the pipe to few feet off the house if your grounds slope away from your house or you may even need to dig out a DRYWELL and run a line into that.

No vent or traps needed on perimeter drains.

Let me know if you have questions here...

Mark