# Forum Home Renovation Bathrooms  P-trap toilet replacement - distance from wall?

## KANDL

Hi All,  
I know I'll need to get a plumber in to give me the final answer on this one, but thought I'd ask the question here first... 
We will be replacing our current p-trap toilet (probably around 20 years old) in our ensuite renovation.  Behind the toilet (and matching bidet - which we will be removing) there is a small hob built on the wall (about 12cm in depth).  We believe the hob contains the pipes for the toilet, bidet and hand basin and are hoping that we will be able to do away with it in the renovation so as to have one smooth wall.  Have attached a picture in which you can see the hob (currently being used as a shelf!).   
My question relates to whether there are likely to be issues in replacing the toilet without the hob - it would mean moving the toilet 120mm or so further back against the wall - not knowing anything about toilets and sewerage issues I'm just wondering whether this would be possible.  The wall is plaster board / brick veneer.  
Planning to start removing tiles this weekend to better see what we're dealing with.   
Anyway, any thoughts welcomed.   
Cheers, 
K

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## Vernonv

If you remove the hob you will have to route the toilet waste directly out the wall or directly through the floor. Is that what you are planning to do?

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## KANDL

Well this is what I think we'll have to get a plumber to tell us  - it's an upstairs ensuite so going through the floor would be problematic (probably not really the ambiance we'd be looking for at dinner parties!!   :Smilie:  ) and not sure how much room there is in the wall cavity - probably why the hob was built in the first place.   
I guess I'm just wondering if there's a standard minimum distance that the sewerage piping needs to be from the back of the toilet - I think that will determine whether we can lose the hob.  Maybe it will come down to careful choice of the replacement toilet, not sure.

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## Vernonv

> I guess I'm just wondering if there's a standard minimum distance that the sewerage piping needs to be from the back of the toilet - I think that will determine whether we can lose the hob. Maybe it will come down to careful choice of the replacement toilet, not sure.

  I've got to admit, I'm a tad confused by your question. Are you asking how far the pipe has to stick out from the wall?
Normally this is dependent on the toilet used. We recently installed a "back to wall" toilet and it needed to have the pipe sticking out about 140mm from the wall.
However, like I said in the original post, you will only be able to get rid if the hob if you change the pipe so that it exits through the wall (generally not enough room within the cavity) or through the floor.

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## KANDL

Yeah, you're understanding what I'm getting at - sorry for being confusing!!  The problem I'm having is that all the specs for p-trap toilets I've looked at so far all talk only about the distance from the floor to the centre of the outlet pipe in the wall - that part I get and have no reason to change it, as far as I can tell.  As you've suggested, I'm wondering about the distance from the wall to the toilet itself - because the hob is 120mm and then there's the distance from the hob to the toilet itself, I'm wondering whether we can do away with the 120mm.  Is very confusing - sorry!!   
Think I'll just bite the bullet and get a plumber in next week to let me know what we're dealing with.  Can't really look at what new toilet to purchase until I know what measurements to be looking for.   
Thanks for trying to help despite the confusion!   :Smilie:

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## Ronaldo451

Kandl, I am also having a little trouble getting a picture of what you have and what you want in regards to the question you are asking.  
If its a P trap then I thought it would exit straight out the backwall.  
The complication with the hob being brought into the equation appears possibly to be that the waste pipe goes horizontally into it and then veers off in another direction, either sideways or downwards to exit the outside wall somewhere else other than directly behind the toilet...is that the case?  
If so do you mind having exposed stackwork on the outside wall if you got rid of the hob and had the waste pipe going straight out the back? 
The short answer to your question is that the distance a P trap toilet is offset from the wall, in my experience, is only that required to allow the cistern to be fixed to sit behind it or, if the cistern is somewhere else (in the cavity or in the ceiling) for the seat to be able to lift up and stay there while gents do their bizz. 
There is no critical distance or length for plumbing purposes, only the prgamatics of making everything fit togther ....as far as I am aware....

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## KANDL

Yes, Ronaldo451, you've described our set up exactly - the waste pipe exits horizontally into the hob and, I assume, then travels down the inside of the wall - 2-3 stories down - and re-emerges to the outside of the bricks at the base of the house (we live on a very steep block and the ensuite is on the 2nd story of the house).   
Not too attracted to the idea of having the exposed stackwork - would run along the wall smack bang in the middle of our entertainment area on the deck outside.   
Am hoping your assumptions about offset distance are right and that the problem will simply be a matter of shortening the waste pipe so that we can position the new toilet against the wall rather than forward due to a hob.  Will get a plumber in next week to have a look once we've removed our tiles.   
Cheers, K

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## q9

> Am hoping your assumptions about offset distance are right and that the problem will simply be a matter of shortening the waste pipe

  That's all I had to do to fit my new toilet upstairs...knocked about 3 inches off the pipe and fitted a new coupling piece.  Was very easy.

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## KANDL

Bit of an update... 
We removed the hob and have had the plumber in for a sticky beak.  Outcome?  Two very viable options:
1. move toilet to one side slightly to where vanity is currently positioned (which would actually probably work better for the overall layout of the bathroom) to get around a problematically positioned joist - install new P trap with reconfigured outlet piping. OR
2. convert to an S trap and run waste under floor to outside wall - being 2nd level, have a decent enough subfloor space to play with.  Only potential issue with this could be beam positions in the floor - will know more when we knock out the existing vanity and can have a look under the floor.   
Also looking at getting a BTW toilet for the replacement which should also help hide any extra pipes.  And so the fun continues!

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## journeyman Mick

Another option would be to get a skew trap pan. (Exits left or right depending on which one you buy) This will get your pan closer to the wall. 
Mick

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