Cost of adding a bathroom to a 3/1

Has anyone done this in San Jose or have info? I am looking at a rental which is 3/1 and trying to figure out the cost of adding a bathroom to it to make it more rentable.

Awhile back we remodeled a preexisting bathroom for $10k. Everything new w/ midrange finishes. I’d imagine adding a bathroom from scratch could run $30k+ but have never done it myself.

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Just 30K? That’s much cheaper than I expected… I have not done bathroom addition and don’t know the cost.

The cost can range from 20k to 100k, depending on if you are just modifying the internal layout or actually adding square footage to the house. Also, whether you get a permit to do it or not. Plumbing can be a factor too: if you have to dig into concrete to install new pipes that could be costly.


Agreed. Probably more. I’m not sure.

With the current Bay Area Construction demands - it will be more on the higher side 50K+. May need to include additional infrastructure upgrade to water capacity/heater/etc. to meet building code which it always does…

Giving the amount and value involve - I would either wait or do it right (avoid under the table non-permitted contractors).

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Doing major things like adding a bathroom under the table is a big no-no. I’d want the added bathroom to go into the tax record to goose up the house value. You can’t do that without proper permits.

If you are truly adding a new bathroom and not converting some existing space into a bathroom, it probably doesn’t make sense to only add one bath, unless there are other constraints that limit expansion. You will be doing foundation, framing. plumbing, electrical, mechanical, interior finish, exterior finish, roofing, etc, plus architect work for just one bathroom. The incremental cost to add yet another bathroom or throw in more expansion/remodeling work will be relatively low.