Ask Your Question

Angie's List Answers is the trusted spot to ask home improvement and health questions and get answers from service companies, health providers and consumers. For ratings and reviews on companies in your area, search Angie's List.

Top 30 Days Experts
Rank Leader Points*
1 kstreett 240
2 Guest_9020487 110
3 Guest_9190926 105
4 GoldenKid 100
5 ahowell 95
6 KnowledgeBase 95
7 skbloom 80
8 Guest_98024861 70
9 Guest_9311297 70
10 Guest_9400529 70

*Updates every 4 hours

Browse Projects By Category

Question DetailsAsked on 7/5/2014

Can I add on a bathroom with free standing plumbing?

My house is on a slab and the existing plumbing is on the other side of the house. Is there any way to add a new bathroom?

Do you have the same question? Follow this Question

2 Answers


Given enough money hes there probable is. Actually depending on the locations of the utility lines in the house it may be more or less expensive. If your existing bath is to the rear of the house and the utillities exit to the front it is a question of finding the main line for the sewer and connecting it there. The hot and cold water supplies will be a bit harder and may need sheet rock work to do. The sewer line being the biggest is the hardest one. If all the plumbing is to the rear of the house it will be more costly but anything can be done.


Answered 6 years ago by ContractorDon


As Don said, can always do it, just takes more money than usual for the long piping runs and avoiding issues along the way.

Water pipes (hot and cold) can be run through floor joists - quite cheap if open crawlspace or basement with exposed joists running the way you want to go, say 10-20% more if running crosswise to joists (this is where Pex comes into its own because can be fed through joists easily, even though I hate the stuff and would prefer to run one continuous length of pipe from a 1 inch outside wall penetration in this case), and if the upstairs floor joists are covered with drywall or whatever (certainly the case for you) then you have subsequent repair of drywall ceilings after running the pipe. For houses with fancy textured ceilings that are hard to duplicate, or fancy metal panels in the ceiling or such, then you sometimes have to get creative and go through attic or walls (even outside walls at times depending on winter temperatures in your area) to minimize ceiling/wall damage.

Two other alternatives rarely used but doable are to run a new branch on the underground waterline to the new location, then put a dedicated second water heater or tankless heater there for the hot water - avoids having to run hot and cold through the house itself. A new hot water source can be handy also as it eliminates the lag in hot qwater arriving from the other end of the house, which sometimes requires a recirculating system (so another hot wter pipe run) to keep the water hot at the new bathroom - especially if one where baths/showers are goingto be common. Another alternative is to run an enclosed utilidor (a frames out box on the wall, insulated in most some climates) through the attic or just below the eaves to carry the pipes to the other end/side of house.

So - lots of ways to do the water pipes, just costs an extra $500 in most optomistic case -couple of thousand depending on the distance and solution chosen - plus commonly $500-1000 range for drywall repairs if wall/ceiling penetrations were needed.

The sewer is commonly the more expensive part, because it has to run downhill (you do NOT want a lift pump in your house if humanly avoidable) so can't be run up and through floor joists or such. No big thing to run it from new bathroom outdoors, then trenched to intersect existing pipe somewhere outside the house IF the gradient is there to allow that - requires finding out where your sewer pipe is and how deep and such, and may have to be insulated or heated if needs to be shallow towards the start to get required gradient in the trench and you are in an area with freezing ground in the winter.

Gets iffy in cases where you do not have the gradient, which commonly happens in septic/leach field systems where the septic tank was located based on minimal gradient using the existing plumbing, so coming from further away with a new pipe can result in inadequate gradient. New sewer run likely to run $1000 at least, and can be double or triple that pretty easy if running length of house or have to run down toward the street away to get the interception with adequate gradient or has to cross interior floor to get to outside rather than just a couple of feet to get outside from an outside wall bathroom. That cuttingthrough the slab to get the pipe to the outside can cost a thousand or two itself PLUS cost of repairing/replacing the flooring, so a design that puts the bathroom on the outside wallthe sewer pipe has to exit from can save substantial cost and hassle, as well as avoiding poissible future costs in event of pipe problems.

That cost has to include at least one new cleanout and commonly two standpipe cleanouts - one in house at "start" of sewer, and one outside house leading towards the connection with the existing line, and in some code areas a third one at the wye, which does not add to the cost noticeably but needs to be planned for and shouldnot be in the middle of a drive or walk or such, or where people are likely to drive, which may affect planned route.

My recommendation - particularly since you are undoubtedly going to need plans both for building permit application and for contractors to bid on, is get an architect on board initially to work up plans for you - typically $250-500 for a site visit and initial concept discussion, then I would not be surprised if a bit of digging will be necessary to locate pipe depth for a few hundred $, then probably another $500-1500 range for full plans and specs and detailing of utiliity connections because you need to consider electrical runs and possible panel upgrade too if your panel is already to capacity or you plan on electric heat in the bathroom.

All in all, certainly doable though I would advise against it if requires a lift pump for the sewage - otherwise cost probably similar to regular new bathroom plus a couple to a few thousand extra.

Note - unless the bathroom will front on the existing sewer pipe or septic tank side of the house, usually will require cutting through the floor slab leading to that wall, meaning destroying or taking up that flooring.

Answered 6 years ago by LCD

Related Questions

Terms Of Use
Privacy Policy