Water pipes under screed

[GreenGables]

So the plumber has laid all our copper pipework on the concrete subfloor and this has been covered with insulation and the underflowing heating pipes clipped on. Screed is due to be poured soon. 

 

I am concerned that there is no access to the pipes should there be a problem. We would have to dig up the floor. Is this good practice? Is there anything I should be checking before the screed is poured? The buried pipework has soldered joints and includes cold mains drinking water as well hot. 

 

Thanks for any advice.

[nod]

Whilst I’m not a plumber I definitely wouldn’t put pipes under a screed 

Joints can leak Surely there must of been an alternative route Ceilings?

[markc]

No problem burying continuous runs of plastic but copper, big no!

[JohnMo]

I thought building regs allowed it, but had to be replaceable, so fixable and in conduit?

[Conor]

Needs to be in a conduit.

 

Are the copper pipes fixed to the concrete slab? You mentioned hot water pipes... Are they not insulated? It would be more normal to put the pipes on top of the insulation or though the middle of it.

 

But as above, you run a pipe another way before burying it.

[GreenGables]

The pipes were not clipped to the subfloor. It’s all covered with insulation now and I didn’t see if they insulated the pipes first or put conduits around so I’ll ask the builder how they have protected the copper pipes. Thanks for the comments. 

[Conor]

3 minutes ago, GreenGables said:

The pipes were not clipped to the subfloor. It’s all covered with insulation now and I didn’t see if they insulated the pipes first or put conduits around so I’ll ask the builder how they have protected the copper pipes. Thanks for the comments. 

Whos supervising the build? Lift up the boards yourself and have a look. I'd be concerned if there are copper pipes with joins that aren't correctly secured, all it takes is a knock or a misplaced foot. Has it been pressure tested?

 

Just thinking that you won't even be able to dig up the floor if there is a leak as your UFH pipes will be in the way if I'm understanding correctly?

[JohnMo]

I would read your country version of building regs out and see what is allowed.

 

In Scotland any pipe has to be replaceable if buried in a floor.  So cannot be copper as you cannot get the pipe out.

Edited December 7, 2022 by JohnMo
Missed words

[GreenGables]

Hi Conor. Unfortunately we’ve only just realised that supervision has been inadequate. The architect is now checking in every week. I will ask him to check the pipes are adequately protected. We have a few days before screed goes on so should be possible. The whole thing has become a bit of a nightmare. Thanks for all your help. 

[GreenGables]

4 minutes ago, Conor said:

Whos supervising the build? Lift up the boards yourself and have a look. I'd be concerned if there are copper pipes with joins that aren't correctly secured, all it takes is a knock or a misplaced foot. Has it been pressure tested?

 

Just thinking that you won't even be able to dig up the floor if there is a leak as your UFH pipes will be in the way if I'm understanding correctly?

Most of the pipe work is around the edges and kitchen units are above so I don’t think underfloor heating will be over them. 

[GreenGables]

So apparently the copper pipes are wrapped in hessian. The architect and builder think this is fine. Should I accept this?

[JohnMo]

6 hours ago, JohnMo said:

I would read your country version of building regs out and see what is allowed.

 

In Scotland any pipe has to be replaceable if buried in a floor.  So cannot be copper as you cannot get the pipe out.

As I quoted earlier

[GreenGables]

Thanks. I can’t find it. Anyone know which English BR Part refers to water pipes under screed?

[TerryE]

@GreenGables, lots  of us have in-slab UFH.  @nod's point about joints leaking is correct but the inference isn't.  With current BReg any in-screed joints should be accessible but again, the simple answer is not to have any.  Our slab has an internal footprint of ~ 75m² with UFH split into 3 × ~95m loops.  We also have a manifold-based cold + hot potable water system with all sink and whitegood connections 1-1 from manifold to wallplate: no internal joints anywhere.

 

The UFH  pipes are PexAlPex.  Unless you drill a hole through the middle of one, they ain't going leak in my lifetime.

Edited December 7, 2022 by TerryE

[Spreadsheetman]

I’d be pretty unhappy about copper pipes in screed if there is any other viable option, especially in a new build or extension where there is no excuse.

 

I’ve got both H+C water and CH copper in the 70s chalet that I am renovating and I am bypassing all of it. I just don’t want to take the risk.

[Nickfromwales]

If copper is not in contact with screed / cementitious products etc then it is the weapon of choice for fit and forget in anyone’s lifetime. For installs ( triple digits ) where I have done this, I have always wrapped ( mummified ) the copper pipe; firstly with gaffa tape immediately on the pipe, then Denzo tape, then hessian ( aka cozy-wrap ) for movement. Insulation on heating pipes was the norm, but not for hot water pipes ( : crowd gasps out loud : ).

I’d put my money on a soldered joint over push fit each and every single day. 
I use Hep2O on almost every single new building where the pipes traverse the dwellings fabric / open spaces to avoid joints where they cannot be accessed, but if I did the same run in copper I’d be an even happier bunny, albeit with the knowledge they there would have been at least one joint every 3m. 

It’s very interesting to read the comments of folk who have not been actively plumbing for 30+ years, as I have, and for their assumptions to be versed so strongly.

 

Mechanical joints under screed is lunacy, push fit or compression, but a copper pipe and it’s soldered joint will very likely still be fit and healthy enough to attend your funeral. 
 

Reality-check time people!!!

[GreenGables]

6 minutes ago, Nickfromwales said:

If copper is not in contact with screed / cementitious products etc then it is the weapon of choice for fit and forget in anyone’s lifetime. For installs ( triple digits ) where I have done this, I have always wrapped ( mummified ) the copper pipe; firstly with gaffa tape immediately on the pipe, then Denzo tape, then hessian ( aka cozy-wrap ) for movement. Insulation on heating pipes was the norm, but not for hot water pipes ( : crowd gasps out loud : ).

I’d put my money on a soldered joint over push fit each and every single day. 
I use Hep2O on almost every single new building where the pipes traverse the dwellings fabric / open spaces to avoid joints where they cannot be accessed, but if I did the same run in copper I’d be an even happier bunny, albeit with the knowledge they there would have been at least one joint every 3m. 

It’s very interesting to read the comments of folk who have not been actively plumbing for 30+ years, as I have, and for their assumptions to be versed so strongly.

 

Mechanical joints under screed is lunacy, push fit or compression, but a copper pipe and it’s soldered joint will very likely still be fit and healthy enough to attend your funeral. 
 

Reality-check time people!!!

That's really helpful thanks Nick. I will ask if the pipes were taped first as they only said they wrapped them in hessian. 

[Nickfromwales]

1 hour ago, GreenGables said:

That's really helpful thanks Nick. I will ask if the pipes were taped first as they only said they wrapped them in hessian. 

If they are not in contact with a cementitious product then no harm will come to the copper. 
The question you need to ask is how poorly will they be / what heat will be lost to the sub floor before it gets to its destination. 

[TonyT]

I’m sure the byelaws prevent having cold water pipes in screed where UFH is in place.  
will have to do more digging in the paperwork to support this.

[TonyT]

Ps get 6 metre  long copper pipes delivered!

less joins 😁

[nod]

10 hours ago, TerryE said:

@GreenGables, lots  of us have in-slab UFH.  @nod's point about joints leaking is correct but the inference isn't.  With current BReg any in-screed joints should be accessible but again, the simple answer is not to have any.  Our slab has an internal footprint of ~ 75m² with UFH split into 3 × ~95m loops.  We also have a manifold-based cold + hot potable water system with all sink and whitegood connections 1-1 from manifold to wallplate: no internal joints anywhere.

 

The UFH  pipes are PexAlPex.  Unless you drill a hole through the middle of one, they ain't going leak in my lifetime.

Regardless of any regulations I wouldnt put a joint where I had no reasonable access

UFH pipes are bombproof But run in continuous loops 

 

ive lost count of the times I’ve taken ceiling’s down on new builds due to leaks Inconvenient But easier than hacking a floor 

Tell him to take them up a wall and along the ceiling 

[TerryE]

@nod, I think that we are saying roughly the same thing: avoid buried joints; make them reasonably accessible if unavoidable. We did this by design in our current build.

 

Rereading the OP, if this wasn't installed to a professional standard / quality then the risks are serious.  This isn't a case of "on trust" IMO.  The plumber needs to give evidence of quality: eg. no buried Ts, minimum joints that have been solder-jointed where to be over-screeded.  DHW properly insulated from thermal bridging.

 

The whole system should be pressure tested to ~6 bar for multiple hours before  the screed is poured.  Yes, any joint failures that occur are an inconvenience but this will be an order of magnitude less than the remediation costs if the failure occurs after the screed goes down.

 

@Nickfromwales, you're the expert here. What would you advise?

[Nickfromwales]

1 hour ago, TerryE said:

@Nickfromwales, you're the expert here.

Lol. Maybe I should charge more!

1 hour ago, TerryE said:

What would you advise?

Pay me more? 
 

Moving swiftly on…….
 

Basically, avoid putting pipes in / under solid floors unless absolutely every other option has been explored and deemed utterly impractical ( cost or execution ) or impossible.

Don’t forget you can buy soft pvc coated coils of copper pipe in 15mm and 22mm sizes which will allow a very robust pipe to be fit and forgotten with zero joints ( if you can get under and out again in a 25m length ).
https://www.jtmplumbing.co.uk/pipe-fittings-c433/copper-pipe-6mm-219mm-c174/kitemarked-copper-tube-coated-coils-copper-pipe-p7253

 

Barely any cheaper without the coat……

 

https://www.jtmplumbing.co.uk/pipe-fittings-c433/copper-pipe-6mm-219mm-c174/kitemarked-copper-tube-copper-pipe-coils-p10984

 

If I had to go under, that would be the choice. That or Hep2o tbh. If you go for the non coated copper you can put tight bends in it with a bending machine ( manual pipe bender ) so depends on route / situation / application. 

[Nickfromwales]

9 hours ago, TonyT said:

I’m sure the byelaws prevent having cold water pipes in screed where UFH is in place.  
will have to do more digging in the paperwork to support this.

You must prevent a cold mains pipe from sitting at ambient for mitigation against legionella, but once it’s inside the dwelling it will be assumed that it will be drawn off sporadically / often enough for this to not be considered any risk. 
How many houses are there where the 5 pipes are all in the same floorboard space, tucked snugly against one another, and nobody dies!

That said, anyone who puts a ( non insulated ) cold feed through a heated floor is a cock. 

[GreenGables]

Here are a few photos of what’s been done. Doesn’t look great to me.