How to Install a Basement Bathroom | Ask This Old House

Richard Trethewey shows how to rough-in the drainpipes for a basement bathroom. (See below for steps.)

Richard used standard schedule 40 PVC pipe for the new drain lines. All of the supplies for this project, including PVC, glue and cleaner, and flexible couplings, are available at home centers and plumbing supply companies.

Steps for How to Install a Basement Bathroom:
1. Lay out the 2x4 bottom wall plates to establish the perimeter of the bathroom walls.
2. Measure off the wall plates to locate the center of the shower drain and toilet flange.
3. Dig a trench extending from the existing drainpipe over to the new locations of the shower drain and toilet flange.
4. Use a right-angle grinder fitted with a diamond-impregnated cutting wheel to cut through the old cast-iron drainpipe.
5. Attach a flexible no-hub mechanical coupling onto the end of the just-cut drainpipe. Tighten hose clamp onto the cast-iron pipe with a torque wrench.
6. Cut and glue together 3-inch-diameter PVC pipes and fittings to form the drainpipe assembly that connects the old cast-iron pipe to the new shower and toilet drain.
7. Slip the end of the PVC drainpipe assembly into the mechanical coupling attached to the old cast-iron pipe. Tighten the hose clamp to secure the PVC pipe.
8. Next, run 2-inch-diameter PVC pipe from the drainpipe assembly over to the shower and vanity sink.
9. Install traps for each fixture, and be sure the pipes slope 1/8 inch per foot to drain properly.
10. Drive a 1/2-inch-diameter steel-reinforcing bar down into the soil beside each trap. Then, use duct tape to secure the bars to the traps.
11. Have the rough piping inspected before pouring the concrete floor.
12. Cover the open end of the toilet pipe with a foam cap. Wrap plastic around the shower-drain pipe.
13. Have the concrete contractor pour a new floor around the piping.

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How to Install a Basement Bathroom | Ask This Old House

[mcoygarcia]

im a plumber myself and ive done underground rough ins, I have to say that this video is very explainable for anyone who is not a plumber and wanted to do their own plumbing. good enough video

[RayR]

Richard is so humble. My favorite member of this old house.

[generaldiego]

Growing up and even now still this show is just dope

[copykonsmusic]

This is the easiest install of all time being that there was already a bathroom there. Where I live, no one cares if you move your toilet from one side to another, but in states like NJ and NY it's endless bureaucratic red tape and paying for inspections.

[PatrickDeschamps]

I was frying my head trying to understand what the heck was that pipe going absolutely nowhere in my basement. Thanks to you guys, now I fully understand the reason. You guys are awesome!

[cannonplumbinganddrainllc]

you never want to use flexible couplings under the concrete but rather a solid metal banded coupling with a rubber behind it, its called a mission band, over time flexible rubber couplings can flex to much, if shifting occurs in the ground that could potentially obstruct the flexible coupling they used in this video, what they used is a fernco, I suggest a mission band.

[billcorbet]

Been in the trades 16 years. Have had a master plumber, master electrical, and master hvac license for 11 of those years. I am now a building inspector.

First thing I see is working clearances to the breaker box when walls are built, you are not going to have three foot in front of it. Looks like about 32 inches if you go by seems in the blocks, and that's not counting that the front of the breaker box is four inches from the wall surface to start with.

Second thing, depending on code they are on, they may or may not have done the venting correctly. As a plumber I would have vented the toilet separately, however depending on the code for that jurisdiction they may be within code, however codes are minimum standards, nothing saying you can't do more, and all we are really talking about is a few more dollars in fittings, not much in the overall cost of adding a bathroom.

Third that is going to be a finished area, I would have depending on circumstances outside, dug down outside and made it to where I had PVC to outside of the home, as well as installed cleanouts on the outside of the home, again not required to do that per code, however why mess up a perfect finished area when cast iron fails, and it will fail. I might also would consider a check valve in the event of a sewer backup you don't flood the area, however check valves do fail, and that can be a problem too.

[jonpos]

I was after the info at the very end, as I'm ready for concrete, but was concerned about the pipes getting bound. Good tips.

[jakejones]

The old cast pipe moved as they tightened it! Among plenty of other issues!

[SurferKenTV]

Great! I’ll start excavating my basement to look for any vintage drain pipes. Hope I find one!

[fnhwk]

Richard is one of a kind. Great teacher, he is truly passionate about plumbing/HVAC

[scottobrien]

consumer tip, if it's only a few more feet to get outside of the house, then have your plumber go ahead and replace it. If that "80 yr old cast" fails 6 months later, then your tearing out brand new floor, tile.

[bitDude]

As a aspiring plumber this channel is extremely fun to watch and also motivating. Thanks. :-)

[amdemik]

I don’t really care about this video much but I just love reading comments. Such a fun time. God bless YouTube, God bless American inventors.

[saulgoodman]

This guy is a professional plumber, and you have Richard talking to him like he doesn't know what he's doing.

[GooseGosselin]

I like how the cast iron pipe was moving as they were tightening up the clamp.

[B.r.i.a.n.]

I see alot of comments about the wet vent smelling bad, it's not to open air. It either ties into the buildings existing vent or if code permits you can get a $20 one way vent that only allows air in. Wet vents work well. I may have added an additional vent for the shower at least but just my opinion .

[djstl]

1#...Use a soil pipe cutter.
2#...use some kind of 1/2" minus or screenings to support piping from underneath, before concrete comes.
3#... Box off shower for drain install..not wadded up plastic.

[julianantun]

4:15 loved how he gently put his hands on the pvc cause he knew his buddy was dealing with a saw

[Alleriux]

You should have installed a backwater valve to protect the bathroom since this is the basement . Also our plumbing code mentions that you need 1/4 per feet pitch for a pipe that is 3"or less. 1/8 per feet is for pipes 4" to 6".