Adding Plumbing to Attached Garage

Old 01-16-17, 11:36 AM
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Adding Plumbing to Attached Garage


I have a 1940s era house with a basement, 1st floor and 2nd floor. The Basement is unfinished, as is the attached Garage. I would like to make one of these spaces liveable and we need to add a second bathroom or powder room.

Evaluating cost and due to issues with water/moisture in the basement i've decided on the garage. I'm fairly handy and will be doing most of the other parts of this projects myself. Im not great with plumbing however.

I'd like to run the plumbing for a toilet into the garage which shares a wall with the first floor kitchen and the basement. Pictures are attached.

I'd like to get an idea of how extensive this project would be and if i hired someone what costs i could anticipate.

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The garage is currently unfinished as previously mentioned. The floor is concrete and i would eventually like to level it out and have carpet or pergo flooring.

Any ideas on how much something like this would cost ballpark? In regards to the DIY part of the project is there anything i should know before we do the plumbing for the toilet?
Old 01-16-17, 01:55 PM
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Since we do not even know what state you live in the best cost estimate is going to be somewhere between $5,000 and $50,000.
Old 01-17-17, 05:40 AM
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My Apologies, Located in Delaware.
Old 01-17-17, 10:11 AM
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I think it's certainly doable. Plumbing-wise, I don't see it being a huge project since it's all above the main drain and your plumbing is all nearby. The biggest cost for the plumbing will be to cut through the cement floor to run the drain pipes into the basement.

Have you considered building up a floor? It will add some cost to frame out a floor with 2x6 joists, but will allow insulation, plumbing, and a nice, level floor. If you have the ceiling height (and door heights), I'd definitely go that way.

Also, check your local building department. Some areas forbid doing a garage conversion, or require houses to have a garage. You also may need zoning approval for it. Hopefully not - but better to know now than after it's all done!
Old 01-17-17, 12:09 PM
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Thanks Zorfdt: I don't see this being a huge project but i dont know what the cost would be, so when i have some folks come in and give me an estimate i'd like to know what to expect.

I did consider building up the floor and it's definitely the direction i will be going. I just kind of wanted to get a ballpark for the cost of the running of the plumbing through the cement floor and what types of materials are typically used to do that? the pipes in our house are old/dated.
Old 01-17-17, 12:22 PM
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The actual cost of the piping to rough in for a bath in the garage would be a few hundred. As already mentioned one of the big things that determines the labor cost for the plumbing would be how you want it done.

If you want to keep the floor at it's current elevation then the concrete floor will need to be sawed to each fixture. Trenches dug, piping installed, trenches back filled and concrete poured on top. This would preserve the most ceiling height but you'll have a concrete floor with it's related moisture issues. Also, most garage floors are sloped so water drains out the door. That slope is not objectionable in a garage but if your put your bed sideways on that slope it might be quite noticeable.

If you decide to build up the floor then the plumber has a much easier job. They would only need to penetrate the concrete and block wall enough to get the drain pipe through. All the other drain piping could be run in the new floor joist bays. Raising the floor will allow you to make it level, add insulation and you'll have a softer feel under foot. This would also give you the chance to make the new bedroom's floor flush with the rest of the house.

In either scenario locating the new bath as close to the current drain will help the cost a lot. If the bath is right on the other side of the wall they an easily accommodate the required fall in the drain pipes. The further away the bath is located the more height the plumbers will need for the drain lines. If cutting through the floor it means just digging deeper trenches. If you build up the floor there will be a fixed height the plumbers have so if the floor isn't built up high enough it might not leave enough room for the piping.

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