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running services under a slab - what ducting?


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Hello all - I need to run electricity and water pipes under our slab to where the kitchen will be. Our floor make-up is: DPM - 400mm EPS - 200mm concrete and the ducting will go under all of it - so run in the ground. Is this the sort of stuff I should be using? https://www.drainagesuperstore.co.uk/product/underground-twinwall-water-ducting-178mm-x-6m-blue.html. I also need to run some gas piping, so guess would use: https://www.drainagesuperstore.co.uk/product/naylor-underground-twinwall-gas-ducting-6m.html

I was originally thinking of using just 110mm soil pipe which I guess would make detailing where it comes through the DPM easier (as it it rigid) but will be a bit more expensive. Either way, can I run water pipes (Hep20) and power cable in the same duct?

Thanks!!

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I used 100/110mm blue twinwall for the water, and 50mm black for electric and comms (2 separate ducts). I bought it as a coil, but what you have linked to will work as well. Your groundworker, if you are using one, should be able to advise 🙂 

 

TIP: If you buy it with draw string in, make sure not to pull it out. I used the tin stuff that was in ours to pull through some stronger blue pull chords. Tie them off securely and label well and clearly until it is time to feed things through

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@Tomthat is a ridiculously expensive way to buy it, you want it in a 50m coil. 

I personally would never run something in drainage pipe as to anybody looking at this later it looks like a waste pipe, they won’t expect it to have a power cable in it. 

Dont run water and electric in the same duct, they will probably want to go to different locations any way, the duct is fairly cheap in the grand scheme of things. 

Add up how many you need you will be surprised how many you actually need. 

Water in

power in

telecoms in

power out,water treatment plant. 

Power out, garage

telecoms out, electric gates and stuff

ducts to any kitchen island, power, hot, cold water. 

 

 

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@Tom If you duct the gas pipe then it will have to be TracPipe and it will also need venting - seriously consider binning the gas hob and going electric induction (assuming this is why you need gas) and save yourself the monumental headache and cost. 

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19 minutes ago, PeterW said:

If you duct the gas pipe then it will have to be TracPipe and it will also need venting - seriously consider binning the gas hob and going electric induction (assuming this is why you need gas) and save yourself the monumental headache and cost. 

Yes we did that cost a fortune, £2-3k including the pipe and the gas sign off for the pipe and won't now need it as we have decided against having gas but I guess it's there ready when hydrogen is a thing🤔.

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38 minutes ago, PeterW said:

@Tom If you duct the gas pipe then it will have to be TracPipe and it will also need venting - seriously consider binning the gas hob and going electric induction (assuming this is why you need gas) and save yourself the monumental headache and cost. 

 

I have just done some gas pipe MDPE straight in the ground under a ground bearing slab.

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4 hours ago, Tom said:

I was originally thinking of using just 110mm soil pipe which I guess would make detailing where it comes through the DPM easier (as it it rigid) but will be a bit more expensive. Either way, can I run water pipes (Hep20) and power cable in the same duct?

 

You must not run different services in the same duct.  Nor can you run them in soil pipe etc.  A total no-no.  You are, however, allowed to run services in the same trench.

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1 hour ago, Russell griffiths said:

@Tomthat is a ridiculously expensive way to buy it, you want it in a 50m coil. 

I personally would never run something in drainage pipe as to anybody looking at this later it looks like a waste pipe, they won’t expect it to have a power cable in it. 

Dont run water and electric in the same duct, they will probably want to go to different locations any way, the duct is fairly cheap in the grand scheme of things. 

Add up how many you need you will be surprised how many you actually need. 

Water in

power in

telecoms in

power out,water treatment plant. 

Power out, garage

telecoms out, electric gates and stuff

ducts to any kitchen island, power, hot, cold water. 

 

 

 

Good point, but we only need it to go a short distance: at the moment we have a run of 110mm soil pipe going from the plant room to under-slab level in the main area, we just need to extend this in ducting to get to the final position where the kitchen is.

 

45 minutes ago, PeterW said:

@Tom If you duct the gas pipe then it will have to be TracPipe and it will also need venting - seriously consider binning the gas hob and going electric induction (assuming this is why you need gas) and save yourself the monumental headache and cost. 

 

Yep, totally get you but just want a bottled gas supply for a gas domino hob, rest will be induction etc.

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7 minutes ago, Mr Punter said:

 

I have just done some gas pipe MDPE straight in the ground under a ground bearing slab.

 

Does this meet regs? Would solve a part of a headache if so.

 

4 minutes ago, Mr Punter said:

 

You must not run different services in the same duct.  Nor can you run them in soil pipe etc.  A total no-no.  You are, however, allowed to run services in the same trench.

Roger that. Unfortunately our totally useless (ex) builders have run 110mm soil pipe in to to the building to take the services.

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2 minutes ago, Tom said:

Yep, totally get you but just want a bottled gas supply for a gas domino hob, rest will be induction etc.

 Why ..??? Or why not put the gas domino on an outside wall and then it’s easy ..?? You’ll be looking thick end of £8-900 for the install with pipework etc, and all the GSR stuff, for what benefit ..? 
 

 

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24 minutes ago, PeterW said:

 Why ..??? Or why not put the gas domino on an outside wall and then it’s easy ..?? You’ll be looking thick end of £8-900 for the install with pipework etc, and all the GSR stuff, for what benefit ..? 
 

 

'cos I want a gas hob, no external wall for the kitchen. Can you tell me what needs to be done and why I would expect to pay £900 for the install? If i'm running ducting then it just needs a pipe pulled through and terminated appropriately no?

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17 hours ago, Tom said:

'cos I want a gas hob, no external wall for the kitchen. Can you tell me what needs to be done and why I would expect to pay £900 for the install? If i'm running ducting then it just needs a pipe pulled through and terminated appropriately no?

I’m no expert, but from what I understand. 

You cannot run a duct for gas under the slab, basically if you get a gas leak it can enter the house via the duct. 

Trac pipe is directly buried no duct. 

 

We we are having an LPG hob, kitchen in centre of house, bottles on an outside wall, gas pipe is surface mounted along the garage wall and runs behind units in the kitchen, all surface mounted all marked up as gas. 

Edited by Russell griffiths
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