Shower waste- is there a way of re-routing ?

benson1980

Hi all,

Could do with some advice. My next DIY project is to redo a shower room and having ripped it all out now I was having a think about whether there is any way i can adjust my shower tray waste in order to get a lower profile 'walk in' style tray rather than raised, which is evidently dictated by how the shower waste can be rerouted.

I've attached some photos of what I have so the old shower tray was obviously on top of the built up bit, with the waste running underneath. This then runs into the eaves, resting on top of the joists, and I presume directly into the soil stack. To access the stack, this is behind a toilet room that I have literally just finished redoing, and I appreciate in hindsight I should have had a think about this before I redid it! 

I am also wondering though whether it's not necessarily a bad thing to be able to have some access to the shower drainage rather than concealed under floor.

Basically I'd welcome any thoughts from others who've done this as I haven't redone a shower room before- in terms of suggestions regarding how to redesign this, or stick with what I have and just sit a shower tray on top. Below this is our dining room and kitchen and soil stack runs internally (in the kitchen)- nothing redecorated as yet there but I assume my options are still limited to cutting notches in the joists which I certainly have no interest in doing unless someone advises there is a way of doing this safely, or boxing which I also don't want to do.

I've attached some photos of the room, the eaves showing the grey shower waste pipe which then runs further to the right where the stack is, and the toilet room adjacent (behind which is the stack; excuse my one slightly wonky cabinet panel which I need to sort) to show what I mean in terms of access- the closed door to the left is the shower room. 

Thanks

.

grumbler

What sort of trap was there and how was it done? Was it (mainly) under the floor boards? If so, I don't see why such high platform was needed for the tray. Also I think special low-profile traps are available for showers.

ThisIsWeird

benson1980 said:

Hi all,

Could do with some advice. My next DIY project is to redo a shower room and having ripped it all out now I was having a think about whether there is any way i can adjust my shower tray waste in order to get a lower profile 'walk in' style tray rather than raised, which is evidently dictated by how the shower waste can be rerouted.

I've attached some photos of what I have so the old shower tray was obviously on top of the built up bit, with the waste running underneath. This then runs into the eaves, resting on top of the joists, and I presume directly into the soil stack. To access the stack, this is behind a toilet room that I have literally just finished redoing, and I appreciate in hindsight I should have had a think about this before I redid it! 

I am also wondering though whether it's not necessarily a bad thing to be able to have some access to the shower drainage rather than concealed under floor.

Basically I'd welcome any thoughts from others who've done this as I haven't redone a shower room before- in terms of suggestions regarding how to redesign this, or stick with what I have and just sit a shower tray on top. Below this is our dining room and kitchen and soil stack runs internally (in the kitchen)- nothing redecorated as yet there but I assume my options are still limited to cutting notches in the joists which I certainly have no interest in doing unless someone advises there is a way of doing this safely, or boxing which I also don't want to do.

I've attached some photos of the room, the eaves showing the grey shower waste pipe which then runs further to the right where the stack is, and the toilet room adjacent (behind which is the stack; excuse my one slightly wonky cabinet panel which I need to sort) to show what I mean in terms of access- the closed door to the left is the shower room. 

Thanks

.

Nice work - very neat loo, very attractive :-)

Ok, the shower waste must have a 'fall' throughout its length. Must. (I'm sure you know this). The existing grey waste appears to be making contact with the tops of the joists, so presumably barely has a fall along that eaves run, if at all? If so, you ain't going to be able to lower your tray unless you can find a way to re-route the grey waste. All this you know :-)

I'm uncertain about some detail. For instance, this toilet is adjacent to the shower room? Where exactly is the soil pipe that the grey waste runs in to?

Can you drill holes through the centres of joists safely? Yes, provided you follow the 'rules' - and you can find these online.

Is there any potential for that white waste pipe continuing straight out through the eaves, and down outside via a hole in the soffit, and then to the 4" soil waste pipe outside?

benson1980

grumbler said:

What sort of trap was there and how was it done? Was it (mainly) under the floor boards? If so, I don't see why such high platform was needed for the tray. Also I think special low-profile traps are available for showers.

The old trap I don't have unfortunately as it went to the tip, but nothing under floorboards- all above and then the waste pipe just exits through a hole in the wall. I will have a look at low profile traps though.

benson1980

ThisIsWeird said:

benson1980 said:

Hi all,

Could do with some advice. My next DIY project is to redo a shower room and having ripped it all out now I was having a think about whether there is any way i can adjust my shower tray waste in order to get a lower profile 'walk in' style tray rather than raised, which is evidently dictated by how the shower waste can be rerouted.

I've attached some photos of what I have so the old shower tray was obviously on top of the built up bit, with the waste running underneath. This then runs into the eaves, resting on top of the joists, and I presume directly into the soil stack. To access the stack, this is behind a toilet room that I have literally just finished redoing, and I appreciate in hindsight I should have had a think about this before I redid it! 

I am also wondering though whether it's not necessarily a bad thing to be able to have some access to the shower drainage rather than concealed under floor.

Basically I'd welcome any thoughts from others who've done this as I haven't redone a shower room before- in terms of suggestions regarding how to redesign this, or stick with what I have and just sit a shower tray on top. Below this is our dining room and kitchen and soil stack runs internally (in the kitchen)- nothing redecorated as yet there but I assume my options are still limited to cutting notches in the joists which I certainly have no interest in doing unless someone advises there is a way of doing this safely, or boxing which I also don't want to do.

I've attached some photos of the room, the eaves showing the grey shower waste pipe which then runs further to the right where the stack is, and the toilet room adjacent (behind which is the stack; excuse my one slightly wonky cabinet panel which I need to sort) to show what I mean in terms of access- the closed door to the left is the shower room. 

Thanks

.

Nice work - very neat loo, very attractive :-)

Ok, the shower waste must have a 'fall' throughout its length. Must. (I'm sure you know this). The existing grey waste appears to be making contact with the tops of the joists, so presumably barely has a fall along that eaves run, if at all? If so, you ain't going to be able to lower your tray unless you can find a way to re-route the grey waste. All this you know :-)

I'm uncertain about some detail. For instance, this toilet is adjacent to the shower room? Where exactly is the soil pipe that the grey waste runs in to?

Can you drill holes through the centres of joists safely? Yes, provided you follow the 'rules' - and you can find these online.

Is there any potential for that white waste pipe continuing straight out through the eaves, and down outside via a hole in the soffit, and then to the 4" soil waste pipe outside?

Thanks! My second effort at at some DIY plumbing and all went reasonably smoothly this time

So...the lighter coloured pipe section has a 90 degree angle join and simply continues across the eaves- this is one single waste pipe. My fault for bad photo- that pipe lagging is in the way. Indeed as you say the pipe will have minimal fall if at all and the one thing I did sort when I refurbed the toilet room, was the basin waste for both the toilet room and the shower room sink (when I come to fit it) as that was a mess and actually had an incline. This is all the same pipework and the waste for the toilet room sink simply goes through to next door, through the partition wall. Therefore I refitted all of that and this actually connects via a 'T' fitting, into that grey pipework further along.

The soil stack is internal and is probably offset slightly to the right of where the toilet is. One option might be therefore to remove some the ceiling plasterboard below and this might give me some access to conceal this pipework through the joists (will google the rules as suggested) and then I can find an access point for the internal soil stack somewhere? 

FreeBear

ThisIsWeird said: Ok, the shower waste must have a 'fall' throughout its length. Must. (I'm sure you know this). The existing grey waste appears to be making contact with the tops of the joists, so presumably barely has a fall along that eaves run, if at all? If so, you ain't going to be able to lower your tray unless you can find a way to re-route the grey waste.

Can you drill holes through the centres of joists safely? Yes, provided you follow the 'rules' - and you can find these online.

https://www.labc.co.uk/news/how-get-it-right-notches-holes-solid-timber-joists
I'd be reluctant to suggest drilling large holes in the joists - They would want to be on the centreline of the joists, so you'd not get enough fall (if any) on that part of the waste pipe.

ThisIsWeird

Yes, I did assume that the white pipe elbowed into the grey one.

Zooming in to the second pic, the ends of these joists are actually sitting nicely on top of the wall plates, so any notches taken out where the grey pipe currently runs - or ideally a little further behind it, ie closer to the joist's ends - 'should' have relatively little bearing on their strength. That's not to say you should cut them with abandon, of course, but the joists should not have a bending force on them in that location, so notches should be of a far lesser consequence. You still need to know what you are doing, of course but there's extra potential there.

You'll likely find that most on-line 'notch' calculators won't help, as this isn't in the normal 'suspended' run of a joist.

Section62

ThisIsWeird said:

Zooming in to the second pic, the ends of these joists are actually sitting nicely on top of the wall plates, so any notches taken out where the grey pipe currently runs - or ideally a little further behind it, ie closer to the joist's ends - should have very little bearing on their strength.That's not to say you should cut them with abandon, of course, but the joists should not have a bending force on them in that location, so notches should be of a far lesser consequence. You still need to know what you are doing, of course but there's extra potential there.

The BiB's are incorrect.

See the LABC guidance posted by FreeBear.  The permissible zone for notching ends 0.07x span away from the wall, or 0.25x span away from the wall for holes. Structural members shouldn't be notched or drilled above a bearing.

Even in cases where it might be possible to drill an oversize 40mm hole through a joist, the difficulty in threading a 40mm waste pipe through the drilled holes should be taken into account, especially in a confined space like an eaves void.

benson1980

Ok thanks all. Really appreciate everyones advice. I think looking at the joist depth it is potentially viable, but I'm probably erring on the side of keeping the raised area and just avoiding cutting notches out of my joists and I can sort some form of decorative plinth. I don't find raised shower trays ugly, if the plinth has been done right so probably one of those things that is not worth the hassle!

Section62

benson1980 said:

I think looking at the joist depth it is potentially viable, but I'm probably erring on the side of keeping the raised area and just avoiding cutting notches out of my joists and I can sort some form of decorative plinth.

It isn't just about the joist depth though, it also matters where along the length of the joist the notch/hole would be made, and what other structural parts are affected.

In your case it appears the roof rafters are not directly supported by the wallplate, but instead are on a top plate which in turn is supported by the joists.  The joists would also appear to be the main members acting as ties to resist the roof spreading, although the picture doesn't show the detail of the connection and what restraint is provided.  As a result, the area of the joists where you might want to notch/drill are likely to have high stress concentrations - and shouldn't be altered without seeking advice from a structural engineer.

Raising the shower tray so the drainage is kept above the top of the joists is probably the best approach here.

benson1980

Section62 said:

benson1980 said:

I think looking at the joist depth it is potentially viable, but I'm probably erring on the side of keeping the raised area and just avoiding cutting notches out of my joists and I can sort some form of decorative plinth.

It isn't just about the joist depth though, it also matters where along the length of the joist the notch/hole would be made, and what other structural parts are affected.

In your case it appears the roof rafters are not directly supported by the wallplate, but instead are on a top plate which in turn is supported by the joists.  The joists would also appear to be the main members acting as ties to resist the roof spreading, although the picture doesn't show the detail of the connection and what restraint is provided.  As a result, the area of the joists where you might want to notch/drill are likely to have high stress concentrations - and shouldn't be altered without seeking advice from a structural engineer.

Raising the shower tray so the drainage is kept above the top of the joists is probably the best approach here.

All received- appreciated. Yes that has confirmed my thinking and I will crack on and leave it as is with the raised shower tray.