Insulated Slabs - Wastes & Showers

[Shaun McD]

Hi all, 

 

We are looking likely to go with a Kore insulated slab and hoping someone can give some clarity on wastes and shower trays etc.

1. What is common practice for non toilet sized waste pipes? Do we put in 4 inch wastes and connect 40mm wastes into these? Thinking sinks, washing machine, MHRV drain, dryer drain etc etc.
2. Specifically for a bath waste, do we just leave a 4 inch waste under the bath and the bath waste will get put into it?
3. Showers - if a tray then do we again just leave a 4 inch waste and leave a recess into the slab to connect the trap? If walk in - same thing?
4. Any other considerations for wastes? 

 

Thanks all!

Shaun

[MikeSharp01]

We created a sunken zone in the slab for the whole wet room and in the middle of that, suitable for the shower tray we went for, a sump from which we ran, through the slab, a pipe to the main 110mm riser, which we boxed for the pour so we could get to the connection in case anything went wrong. So we just have to fit the trap to the pipe, drop the tray in and link the two together and then we can tile the whole place and come out flush with the rest of the houses FFL.

 

[Shaun McD]

On 09/03/2023 at 16:10, MikeSharp01 said:

We created a sunken zone in the slap for the whole wet room and in the middle of that, suitable for the shower tray we went for, a sump from which we ran, through the slab, a pipe to the main 110mm riser, which we boxed for the pour so we could get to the connection in case anything went wrong. So we just have to fit the trap to the pipe, drop the tray in and link the two together and then we can tile the whole place and come out flush with the rest of the houses FFL.

 

 

Thanks @MikeSharp01 was the pipe in the sump a 110mm too? 

Was it same for sanitary wastes? 110mm upstanding through the slab?

[MikeSharp01]

7 minutes ago, Shaun McD said:

Thanks @MikeSharp01 was the pipe in the sump a 110mm too? 

Was it same for sanitary wastes? 110mm upstanding through the slab?

Hi. No the pipe is 50mm in the slab all the sanitary wastes are 110 out of the slab.

[JackofAll]

@Shaun McD FYI

 

Edited March 14, 2023 by JackofAll

[JackofAll]

On 10/03/2023 at 17:55, MikeSharp01 said:

Hi. No the pipe is 50mm in the slab all the sanitary wastes are 110 out of the slab.

 

 

 

Edited March 14, 2023 by JackofAll

[JackofAll]

2 minutes ago, JackofAll said:

 

 

 

Apologies, have the images in wrong order, but you get the idea. 

[Nickfromwales]

You do NOT want to have small bore waste pipes going down and exiting the slab. You need to bring 110mm runs in, in the subbase, and then have 110mm pipe rising vertically, then reducing down in the upper portion of the slab. PVC waste pipe and UG 110mm pipe are two very different materials / beasts, so an absolute "NO" to bringing these out of the foundation, if subterranean. 

[JackofAll]

12 minutes ago, Nickfromwales said:

You do NOT want to have small bore waste pipes going down and exiting the slab. You need to bring 110mm runs in, in the subbase, and then have 110mm pipe rising vertically, then reducing down in the upper portion of the slab. PVC waste pipe and UG 110mm pipe are two very different materials / beasts, so an absolute "NO" to bringing these out of the foundation, if subterranean. 

@Nickfromwales Why is that may I ask? does that mean a 4inch pipe reduced down for every sink, shower, bidet etc. 

Edited March 14, 2023 by JackofAll

[Nickfromwales]

Just now, JackofAll said:

@Nickfromwales Why is that may I ask? does that mean a 4inch pipe reduced down for every sink, shower, bidet etc. 

Defo. That's all I ever do. I've never taken a small bore waste out through a raft, and never will. 

[Shaun McD]

1 hour ago, JackofAll said:

 

 

 

 

Thanks for this @JackofAll Why is the radon barrier between the first and second layer of EPS as opposed to underneath all? I guess it must wrap down under the external EPS300, so why not have it underneath all?

 

1 hour ago, Nickfromwales said:

You do NOT want to have small bore waste pipes going down and exiting the slab. You need to bring 110mm runs in, in the subbase, and then have 110mm pipe rising vertically, then reducing down in the upper portion of the slab. PVC waste pipe and UG 110mm pipe are two very different materials / beasts, so an absolute "NO" to bringing these out of the foundation, if subterranean. 

 

Thanks for the confirmation @Nickfromwales How do you usually go about ensuring these are in the correct spot? They must need a high level of accuracy? 

[JackofAll]

1 hour ago, Nickfromwales said:

Defo. That's all I ever do. I've never taken a small bore waste out through a raft, and never will. 

@Nickfromwales so if using a reducer like in the pic the 110mm flange sits flush to ffl?

[JackofAll]

3 minutes ago, Shaun McD said:

 

Thanks for this @JackofAll Why is the radon barrier between the first and second layer of EPS as opposed to underneath all? I guess it must wrap down under the external EPS300, so why not have it underneath all?

 

 

Thanks for the confirmation @Nickfromwales How do you usually go about ensuring these are in the correct spot? They must need a high level of accuracy? 

@Shaun McD re. The radon barrier, I asked this question a couple of weeks back on here and got no reply AFAIK, have seen it done both ways but the engineer specd it that way for us, forgot to ask him since, will fire on a mail tomorrow.

[Shaun McD]

5 minutes ago, JackofAll said:

@Shaun McD re. The radon barrier, I asked this question a couple of weeks back on here and got no reply AFAIK, have seen it done both ways but the engineer specd it that way for us, forgot to ask him since, will fire on a mail tomorrow.

 

Sounds good, would appreciate if you could let me know what the thinking is! 

[SuperJohnG]

I've got a kore insulated foundation. 

 

I just popped 110mm pipes up where I needed them. You can then run kitchen wastes or toilets into them. 

 

You get 110mm to 40mm reducers and solvent weld boss adapters. Like picture as shown. 

[Shaun McD]

9 minutes ago, SuperJohnG said:

I've got a kore insulated foundation. 

 

I just popped 110mm pipes up where I needed them. You can then run kitchen wastes or toilets into them. 

 

You get 110mm to 40mm reducers and solvent weld boss adapters. Like picture as shown. 

 

Thanks @SuperJohnG I am guessing you could cut them down flush with the slab is needed? Dependent on the correct reducer fitting

[Jenki]

1 minute ago, Shaun McD said:

Thanks @SuperJohnG I am guessing you could cut them down flush with the slab is needed? Dependent on the correct reducer fitting

I'm tempted to get all mine flush with slab finish level with a coupling and a internal blank cap to seal. Then they can be power floated over, and the blank removed when the slab is cured. 

[Shaun McD]

7 minutes ago, Jenki said:

I'm tempted to get all mine flush with slab finish level with a coupling and a internal blank cap to seal. Then they can be power floated over, and the blank removed when the slab is cured. 

 

Sounds like a good idea, would love to hear how it works out! I like the look of the reducer shared by @JackofAll as it would mean you could line up the edge of the 110mm pipe with the internal face of the service cavity, and rotate the reducer to have the waste pipe sit inside the service cavity. Would be working to fine tolerances so would need to be very exact with placement of 110mm pipes which is something I need to solve

[Jenki]

Just now, Shaun McD said:

 

Sounds like a good idea, would love to hear how it works out! I like the look of the reducer shared by @JackofAll as it would mean you could line up the edge of the 110mm pipe with the internal face of the service cavity, and rotate the reducer to have the waste pipe sit inside the service cavity. Would be working to fine tolerances so would need to be very exact with placement of 110mm pipes which is something I need to solve

My Main concern is not pipes close to external walls but pipes close to stud walls(to be built). When laying the concrete you can end up with a hump near the pipe. Flush should eliminate this issue. 

I plan to use the same reducers for the kitchen waste. Accuracy of positioning  of these pipes is important full stop. Some more than others, so setting the height is simple really, plus it will give a visual reference when laying the slab.

 

I'm working on my layout dimensions now. Triangulating the positions from corners   / fixed details on the perimeter seems to be the most logical way of checking the positions.

 

[Nickfromwales]

9 hours ago, JackofAll said:

@Shaun McD re. The radon barrier, I asked this question a couple of weeks back on here and got no reply AFAIK, have seen it done both ways but the engineer specd it that way for us, forgot to ask him since, will fire on a mail tomorrow.

The barrier is placed there to preserve it . I have always put a sacrificial layer of EPS down, and then the DPM / barrier atop that, then the remainder of the insulation down after that. Stops the membrane getting punctured by errant sharps etc. 

 

9 hours ago, Shaun McD said:

Thanks for the confirmation @Nickfromwales How do you usually go about ensuring these are in the correct spot? They must need a high level of accuracy? 

In a nutshell, but no more accuracy than everything else needs!

You can fit them flush, but it's really not necessary to be able to power float over them as the floor at these locations isn't usually "on show" anyways. A quick trowel by the slab guys is all that's required there, so I usually leave them through and exposed. Wrap them in cling film or other thin membrane and circle with expanding foam from insulation > FFL, but only for anywhere where you may need some wiggle room. Areas for the showers etc get heavily shuttered out as it's 15 mins to back-fill or a day of back-breaking work to machine out. I know which one I prefer   

[JackofAll]

Thinking out loud here and stating the obvious, if positioning of all waste pipes are spot on there would be no need for stud walls or boxing out.

Edited March 15, 2023 by JackofAll

[Shaun McD]

10 hours ago, Jenki said:

My Main concern is not pipes close to external walls but pipes close to stud walls(to be built). When laying the concrete you can end up with a hump near the pipe. Flush should eliminate this issue. 

I plan to use the same reducers for the kitchen waste. Accuracy of positioning  of these pipes is important full stop. Some more than others, so setting the height is simple really, plus it will give a visual reference when laying the slab.

 

I'm working on my layout dimensions now. Triangulating the positions from corners   / fixed details on the perimeter seems to be the most logical way of checking the positions.

 

 

I just sent my TF company a question on this yesterday, where I would want wastes within the stud, would they plan to notch or how would they handle. I think if the wall in question turns out to be load bearing then I would chicken out and leave the pipe outside of the frame.

 

1 hour ago, Nickfromwales said:

The barrier is placed there to preserve it . I have always put a sacrificial layer of EPS down, and then the DPM / barrier atop that, then the remainder of the insulation down after that. Stops the membrane getting punctured by errant sharps etc. 

 

In a nutshell, but no more accuracy than everything else needs!

You can fit them flush, but it's really not necessary to be able to power float over them as the floor at these locations isn't usually "on show" anyways. A quick trowel by the slab guys is all that's required there, so I usually leave them through and exposed. Wrap them in cling film or other thin membrane and circle with expanding foam from insulation > FFL, but only for anywhere where you may need some wiggle room. Areas for the showers etc get heavily shuttered out as it's 15 mins to back-fill or a day of back-breaking work to machine out. I know which one I prefer   

 

Thanks for note on DPM, makes sense. 

Nice trick to use foam to make the pipe bigger so it has some movement! 

Do you use anything fancy to ensure the pipes are in the correct place? The guy from Kore mentioned that they are seeing some installers using GPS but I am hoping I could get away with some levels and plenty of maths?

[Nickfromwales]

3 minutes ago, Shaun McD said:

 

I just sent my TF company a question on this yesterday, where I would want wastes within the stud, would they plan to notch or how would they handle. I think if the wall in question turns out to be load bearing then I would chicken out and leave the pipe outside of the frame.

 

 

Thanks for note on DPM, makes sense. 

Nice trick to use foam to make the pipe bigger so it has some movement! 

Do you use anything fancy to ensure the pipes are in the correct place? The guy from Kore mentioned that they are seeing some installers using GPS but I am hoping I could get away with some levels and plenty of maths?

Levels and maths, plus foam or shuttering.

If in any doubt, shutter the thing twice or 3x the size you may need, allowing enough depth to get 2x 15°, or 2x 30° or even 2x 45° male - female connectors in which will give you huge options to offset 110mm connections. 
Sit a 200x200x (x)mm EPS or PIR block centred on too of any 110mm risers, so you can get in, fit the reducer, and make off the small bore waste connections as you need to.

Does GPS actually work that accurately? Like down to the 50mm increments required for this?

[Shaun McD]

39 minutes ago, Nickfromwales said:

Levels and maths, plus foam or shuttering.

If in any doubt, shutter the thing twice or 3x the size you may need, allowing enough depth to get 2x 15°, or 2x 30° or even 2x 45° male - female connectors in which will give you huge options to offset 110mm connections. 
Sit a 200x200x (x)mm EPS or PIR block centred on too of any 110mm risers, so you can get in, fit the reducer, and make off the small bore waste connections as you need to.

Does GPS actually work that accurately? Like down to the 50mm increments required for this?

 

Boxing these out with a 200x200 shutter of either EPS or just shuttering seems like a solid approach. Do you shutter from top of EPS all the way up or from the steel up? Im guessing you would try and have it from EPS as encasing even the bottom inch or two of the pipe would make it pretty tough to move

[Nickfromwales]

1 hour ago, Shaun McD said:

 

Boxing these out with a 200x200 shutter of either EPS or just shuttering seems like a solid approach. Do you shutter from top of EPS all the way up or from the steel up? Im guessing you would try and have it from EPS as encasing even the bottom inch or two of the pipe would make it pretty tough to move

Yup. From the bottom up. I snip the lighter gauge steel to the same size opening as the shutter, and then back fill retrospectively. It seems like a lot at this stage, but trust me, once the pour is done and you have to get in there to alter, that becomes very small very fast