soil pipe running through concrete slab

[idunknow]

hi could you give me your opinions on 110mm waste traveling through 150mm concrete slab, its a garage conversion i have taken floor down allowing for 150mm hardcore 30mm blind DPM 1200 gauge this is where the existing soil pipe bottom level is, i have allowed 200mm for insulation and 70mm screed, and would like your opinions on how to move forward allowing for protection expansion and the possibility of movement due to the clay ground built off. i have checked nhbc & will be changing the toilet access from that T to Y connection, i have been scratching my head for ages on the best interpretation of best practices.

thanks for your time     

[Jenki]

Is the plan to inbed the pipe in concrete?

You need the pipes in the hardcore layer . Also the tee's are a bad / unacceptable idea.

Is there any fall on the pipes?

A diagram of the build up would be good.

Edited April 17, 2023 by Jenki

[Dave Jones]

you want to use swept 'Y' not T's

 

https://www.speedy-plastics.co.uk/shop/underground-drainage/110mm-underground-drainage/45d-t-s-swept-y-branch/

 

[idunknow]

hello yeh im going to change t to y, yes there is a 75 mm fall over the length of 2.8mt this is the end of line for sewer run the rest of run is already built over no option for any greater debth, there will be 20mm of concrete cover at the end of run to 95mm cover of concrete at the lowest end.

thanks for your time 

[idunknow]

just noticed i wrote DPM where blind is apologise this is the other way round cheers

[idunknow]

15 hours ago, Jenki said:

Is the plan to inbed the pipe in concrete?

You need the pipes in the hardcore layer . Also the tee's are a bad / unacceptable idea.

Is there any fall on the pipes?

A diagram of the build up would be good.

yes thats the plan however i sapose i could lay 125mm of insulation first then another membrane then 150mm concrete then 75mm insulation >UHF>then the screed maybe that would be better ? thanks for your time

[Carrerahill]

I am certain your concrete will crack over the pipes, however, does it really matter in this makeup, probably not, you could throw some mesh in but you will then struggle with your 50mm cover. Stronger mix with fibre in it... but then again, thinking about what it is doing and the fact the cracks will be adequately bridged by the PIR, I don't think you will have an issue.  

Edited April 18, 2023 by Carrerahill

[ETC]

Bad idea having all those voids in a slab - move the pipe below - or above - the slab. Where it is above use a concealed system (Geberit) and when it's below get it out of the building as soon as possible, don't over complicate connections (think about blockages and access) and bed all pipes in an appropriate bedding material.

[jayc89]

3 hours ago, idunknow said:

hello yeh im going to change t to y, yes there is a 75 mm fall over the length of 2.8mt this is the end of line for sewer run the rest of run is already built over no option for any greater debth, there will be 20mm of concrete cover at the end of run to 95mm cover of concrete at the lowest end.

thanks for your time 

 

Sand blinding and DPM are the wrong way around. You use the sand to protect the DPM from ripping against the stone. 

[jayc89]

Might be too late for this now, but I would switch it around;

 

150mm conc (FFL)

VCL

200mm insulation

DPM

Sand

150mm MOT 1

 

Run your pipework through the insulation. 

Edited April 18, 2023 by jayc89

[saveasteading]

Making the best of what you have:

 Best take the dpm out and blind (30mm is rather a lot unless the stone is really rough) then dpm down again.

OR Omit the sand over the dpm as it will just mix with the concrete and weaken it. But be very careful not to puncture the dpm. 

Put a concrete surround to the pipes. I think bring it up to concrete level and float it.

Later pour the rest of the concrete. This will protect the pipe and also allow the slab to shrink in a controlled way, with nice straight cracks.

The pir and carry on.

It isn't ideal but will work. By encasing the pipe you are protecting it in a controlled way.

 

Double check that all the falls are OK in the pipes...they can move during the work. After the spirit level, I put a golf ball in each open end as a practical check: don't drop it though or it will always clatter through. This checks the slope but also that there are no obstructions.

And catch the ball before it disappears to the main drain!

 

 

[idunknow]

18 hours ago, Carrerahill said:

I am certain your concrete will crack over the pipes, however, does it really matter in this makeup, probably not, you could throw some mesh in but you will then struggle with your 50mm cover. Stronger mix with fibre in it... but then again, thinking about what it is doing and the fact the cracks will be adequately bridged by the PIR, I don't think you will have an issue.  

yeh thanks that sounds logical cheers

[idunknow]

18 hours ago, jayc89 said:

 

Sand blinding and DPM are the wrong way around. You use the sand to protect the DPM from ripping against the stone. 

yeh thanks i stupid make mistake in diagram the sand is under the DPM thanks cheers

[idunknow]

18 hours ago, jayc89 said:

Might be too late for this now, but I would switch it around;

 

150mm conc (FFL)

VCL

200mm insulation

DPM

Sand

150mm MOT 1

 

Run your pipework through the insulation. 

naa not to late never a rush round here yeh i was thinking about the offects of running pipe in insulation  because of under floor heating it would be prudent to have say 75mm insulation UFH 75mm screed to finish thanks for time

 

75mm screed incasing UFH

75mm insulation

150mm concrete

125mm insulation its enough to cover soil pipes

DPM

blind

stone

[idunknow]

15 hours ago, saveasteading said:

Making the best of what you have:

 Best take the dpm out and blind (30mm is rather a lot unless the stone is really rough) then dpm down again.

OR Omit the sand over the dpm as it will just mix with the concrete and weaken it. But be very careful not to puncture the dpm. 

Put a concrete surround to the pipes. I think bring it up to concrete level and float it.

Later pour the rest of the concrete. This will protect the pipe and also allow the slab to shrink in a controlled way, with nice straight cracks.

The pir and carry on.

It isn't ideal but will work. By encasing the pipe you are protecting it in a controlled way.

 

Double check that all the falls are OK in the pipes...they can move during the work. After the spirit level, I put a golf ball in each open end as a practical check: don't drop it though or it will always clatter through. This checks the slope but also that there are no obstructions.

And catch the ball before it disappears to the main drain!

 

 

thanks for the intresting information i have been very fortunate to have been given such a wide varity of responces thanks for your time

Later pour the rest of the concrete. This will protect the pipe and also allow the slab to shrink in a controlled way, with nice straight cracks.

The pir and carry on.

It isn't ideal but will work. By encasing the pipe you are protecting it in a controlled way. wil do thanks

[idunknow]

19 hours ago, Carrerahill said:

I am certain your concrete will crack over the pipes, however, does it really matter in this makeup, probably not, you could throw some mesh in but you will then struggle with your 50mm cover. Stronger mix with fibre in it... but then again, thinking about what it is doing and the fact the cracks will be adequately bridged by the PIR, I don't think you will have an issue.  

noice one i think i feel the same cheers thanks for your time

[idunknow]

17 hours ago, saveasteading said:

Making the best of what you have:

 Best take the dpm out and blind (30mm is rather a lot unless the stone is really rough) then dpm down again.

OR Omit the sand over the dpm as it will just mix with the concrete and weaken it. But be very careful not to puncture the dpm. 

Put a concrete surround to the pipes. I think bring it up to concrete level and float it.

Later pour the rest of the concrete. This will protect the pipe and also allow the slab to shrink in a controlled way, with nice straight cracks.

The pir and carry on.

It isn't ideal but will work. By encasing the pipe you are protecting it in a controlled way.

 

Double check that all the falls are OK in the pipes...they can move during the work. After the spirit level, I put a golf ball in each open end as a practical check: don't drop it though or it will always clatter through. This checks the slope but also that there are no obstructions.

And catch the ball before it disappears to the main drain!

 

 

thanks i am making the best of what i have yeh the previous diagram of build up i wrote DPM and blind the wrong way around blind is under DPM

Put a concrete surround to the pipes. I think bring it up to concrete level and float it.

Later pour the rest of the concrete. This will protect the pipe and also allow the slab to shrink in a controlled way, with nice straight cracks. i will do this if i pour concrete on pipes thanks for your time

 

 

[idunknow]

1 hour ago, idunknow said:

naa not to late never a rush round here yeh i was thinking about the offects of running pipe in insulation  because of under floor heating it would be prudent to have say 75mm insulation UFH 75mm screed to finish thanks for time

 

75mm screed incasing UFH

75mm insulation

150mm concrete

125mm insulation its enough to cover soil pipes

DPM

blind

stone

 

[idunknow]

20 hours ago, jayc89 said:

Might be too late for this now, but I would switch it around;

 

150mm conc (FFL)

VCL

200mm insulation

DPM

Sand

150mm MOT 1

 

Run your pipework through the insulation. 

 

[idunknow]

20 hours ago, ETC said:

Bad idea having all those voids in a slab - move the pipe below - or above - the slab. Where it is above use a concealed system (Geberit) and when it's below get it out of the building as soon as possible, don't over complicate connections (think about blockages and access) and bed all pipes in an appropriate bedding material.

yes will do thanks for your time

[idunknow]

20 hours ago, Carrerahill said:

I am certain your concrete will crack over the pipes, however, does it really matter in this makeup, probably not, you could throw some mesh in but you will then struggle with your 50mm cover. Stronger mix with fibre in it... but then again, thinking about what it is doing and the fact the cracks will be adequately bridged by the PIR, I don't think you will have an issue. 

[idunknow]

stunning replies thank you all most appreciated i will post pics of the progression that you all have enabled. Respek.

[saveasteading]

You shouldn't need 150 concrete. 100 is plenty. 

Better spent on more insulation above the concrete, under the screed, where it will havd most effect.

 

Also due to the diminishing  effect of insulation lower down, you might use polystyrene at the bottom layer and pir under the screed. 

 

 

 

[idunknow]

22 hours ago, saveasteading said:

You shouldn't need 150 concrete. 100 is plenty. 

Better spent on more insulation above the concrete, under the screed, where it will havd most effect.

 

Also due to the diminishing  effect of insulation lower down, you might use polystyrene at the bottom layer and pir under the screed. 

 

 

 

wow great advice thank you