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Mike R.
Mike R., Plumber
Category: Plumbing
Satisfied Customers: 2884
Experience:  20 years of plumbing experience, including high end homes and service work.
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Is it possible to get help with designing the in-slab floor

Customer Question

Is it possible to get help with designing the in-slab floor drain system for my guest suite? It consists of three fixture bathroom and a kitchen sink draining down hill to a septic holding tank. Must meet code standards, located in Alberta, Canada.Thanks,Terry
Submitted: 1 year ago.
Category: Plumbing
Expert:  Mike R. replied 1 year ago.

Hi my name is ***** ***** I have been in the plumbing field for 20 years. I will be glad to help you today. Will there also be a water heater? No washing machine? Is the access to a vent pipe?

Customer: replied 1 year ago.
No washer and no water heater. I have set up some abs as conduit to bring hot and cold supply lines from the house. I guess the bathroom, kitchen sink and a floor drain will all need venting. I am willing to pay a little more and have the system designed for me to install but it must meet Alberta code. I am anxious to get the slab poured and there are simply no plumbers available in my area. They are all too busy to even come take a look.
Expert:  Mike R. replied 1 year ago.

Very good. I will make a list of rules to follow to help with the design of the drain pipe system. Typing now.

Expert:  Mike R. replied 1 year ago.

You can use a studor vent on the kitchen sink. The vent on the bathroom sink will be enough to vent the bathroom. There cannot be any drain pipes in the slab less than 2" pipe. A trap arm is the pipe that feeds the fixture and has a trap. The sink trap arm will be above the slab and will be 1 1/2 pipe. This pipe can be no longer than 5' and have no more than 1 1/2" of grade. The trap arm for the tub or shower will be in the slab and 2" pipe with a 2" trap. This can be no longer than 6' with no more than 2" of grade. The trap arm for the toilet must be minimum of 3" pipe and can be no longer than 10' with no more than 3" of grade. They connect together tub and sink first then connect to the toilet branch. Use Wye fittings or combination fittings for horizontal connections. Tee fittings can only be used for vertical connections. The kitchen sink must connect downstream from the bathroom group. The trap for the toilet is in the toilet and the traps for the sinks will be installed when the sinks be installed. The only trap installed under the slab will be the tub or shower. Any penetration through the foundation must be sleeved and sealed. The drain pipe must be tested 10' above the flood level rim which means that you would cap off the piping and there would need to be a 10' pipe filled to the top. This is often done where the pipe exits the foundation then 90 degree straight up. The sewer connection is made during another inspection.

Expert:  Mike R. replied 1 year ago.

There are quite a few little details that would be easier to explain in a phone conversation if you would like to do that and take some notes. I am going to be logging off for the night soon as I am on the east coast and it is almost midnight here. If you would like to do a phone conversation tomorrow or have any questions about what has been described so far I could certainly answer those too.

Customer: replied 1 year ago.
What I would really like would be drawn diagrams based on my floor plan, but perhaps that is beyond the scope of Just Answer? I am not concerned about what happens above the slab as long as I have everything in place properly for the real plumber after the slab is poured. I am also signing off for the night so can continue tomorrow. Thanks.
Customer: replied 1 year ago.
Expert:  Mike R. replied 1 year ago.

The only thing I do not see on the plan is where the sewer goes out. Do you know where that will be?

Expert:  Mike R. replied 1 year ago.

I can draw something on the plans you provided once I know about where the sewer will go out.

Customer: replied 1 year ago.
Right. Sewer line will leave the western side of the building, near the SW corner and runs to a holding tank as per my wastewater permit. Tank is to be located SW of the SW corner, probably 25-30 feet away.
Expert:  Mike R. replied 1 year ago.

I am having trouble finding a file sharing site. I tried Wikisend but it will not work. I made a rough diagram. Still trying to share it.

Expert:  Mike R. replied 1 year ago.

I haven't heard from you. Was the information I provided helpful?