Is it advisable to build a bathroom above the garage? What kind of obstacles might we face if there is a bathroom above the garage in terms of piping, insulation, etc.?

  • It depends on the climate you live in. – Tester101 Mar 24 '15 at 2:05
  • ...and whether the garage is heated or not, if the climate is cold. – Ecnerwal Mar 24 '15 at 2:23
  • Where your main waste line exits the house is a consideration too. – Jack Mar 24 '15 at 4:08
  • Would you rather have water leaking into your living room or your garage? – Tyler Durden Mar 24 '15 at 18:59

List of issues:

  1. Getting the space conditioned. This may be really easy or insanely difficult. Depends on what is on the other walls of bathroom and where your ducts are in your house.

  2. Getting electric. Should be no big deal.

  3. Getting water. Might be a bigger deal than electric but probably not a huge thing.

  4. Getting exit plumbing. Given that the bathroom is on a second level you have a lot more options but you will probably have to open a few walls to get plumbing to your main stack. Your shower and faucet aren't a big deal. It is your toilet that would be concern. You don't want to run a long solid waste line with low slope.

  5. Venting. Should be easy since you are on second level.

So biggest issues are #1 and #4 for a bathroom above garage. If you get these easily figured out the rest shouldn't be a huge deal.


Generally speaking building anything on top of garage isn't be idea in the world, but I'm guessing that you are in need and it's not because you have nothing better to do, it can be done, and if you ask me it is not more complicated than doing it anywhere else. First and the most important thing: WATER PROOFING and THERMAL INSULATION. You should have two layers of water proofing; one that is protecting the bathroom from "outside" water (humidity etc.) and the other which is protecting everything else from bathroom water. First layer should be placed on top of garage slab, and second one right under ceramic tiles. I have skipped one step, well actually I'm taking it for granted and that is the question whether your slab can support extra weight. After water proofing put some thermal insulation, and cover it with cement screed. Also keep in mind that your walls and ceiling should also be thermally insulated. Then you put some simple roof on top of it cover it with metal sheets or something similar, if possible put some gutters and that's it. When it comes to plumbing (water and sewerage) that could be the biggest problem, put I cannot tell anything about it since I’m not fully familiar with your situation.

  • Your answer seems to be to the question "building a bathroom IN the garage", not (as asked, albeit with no useful details yet) ABOVE the garage. – Ecnerwal Mar 26 '15 at 15:44
  • @Ecnerwal how do you mean? What do you think that I left out? I haven't mentioned details about building the walls but I'm presuming that implies. If you think I should add something feel free to edit the answer or you can suggest me how. – python starter Mar 27 '15 at 7:43
  • Waterproofing the garage slab...? Somewhat irrelevant for a bathroom above the garage. – Ecnerwal Mar 27 '15 at 15:42
  • I agree that it might sound irrelevant but if you ask me you cannot be to caucus with waterproofing. It doesn't cost too much money but water can cause soooo much damage, so I always think about the worst case scenario. Like there is no guarantee that garage slab is under slope, and water can collect right next to bathroom walls and go under, I don't think that it should be left out. – python starter Mar 27 '15 at 21:56

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.