Conduits in concrete slab - making it all work

[Bancroft]

We're planning on a concrete slab foundation under an ICF build and I'm presently thinking about conduits required to run through the slab.

 

And the list seems to be growing daily!

 

I've got the basics like sewage out, and mains water and electricity in, but it's all the other stuff:

 

Into the house - ASHP, aircon (split system so essentially another ASHP just providing cool v hot), solar/battery, broadband/fibre.

 

Back out - electric gate power (and ethernet for video camera/security), lighting to garage, lighting to garden, water supply to external taps, power out to car charger.

 

And so the list goes on. (Let me know if anything crucial missed).

 

What's the best way to organise these without causing interference between different supplies or ending up with multiple conduits under the slab?

 

Clearly water and electric should be kept separate but can electricity, fibre and ethernet go through one conduit?  Is that a good idea? 

 

Could all electrical supplies go through one conduit or should they be split up?

 

Ditto ASHP and aircon plumbing.

 

Is it worth considering just a single electrical supply out and then putting another meter box in the garage to split all the external requirements from there?  

 

How have others approached this issue?

[Russell griffiths]

Power out for sewage treatment plant if you have one. 
don’t mix power and internet. 
don’t worry about multiple ducts, if you need them that’s it, you need them. 
all power in and power out can come up below the consumer unit, I have about 6 ducts there, then 3-4 more in the plant room for water in and ASHP in and out. 
you will need power out to the ASHP plus maybe cat 6 to control it. 
 Do a sketch of the house and some lines on it of every device inside and out and how each device will get either power or water to it or from it or both. 
I wouldn’t be surprised if you end up with 20 odd penetrations in the slab, don’t worry just get them in, and run a spare just in case. 

[Andehh]

Do not forget insulation size on the pipes!! We had a nightmare of a job pulling 4 x AC pipes through together with the insulation on. 110mm duct was stupidly ambitious, but narrowly managed to make it work.

 

Also bends disproportionately add to the resistance pulling things through.

[Nickfromwales]

5 hours ago, Bancroft said:

What's the best way to organise these without causing interference between different supplies or ending up with multiple conduits under the slab?

Don't be shy, the last M&E spec I delivered had about 17 different ducts for everything. Makes life soooo much easier at 1st fix etc, and for any alterations you may want to make downstream.

[Bancroft]

20 hours ago, Russell griffiths said:

Do a sketch of the house and some lines on it of every device inside and out and how each device will get either power or water to it or from it or both. 
I wouldn’t be surprised if you end up with 20 odd penetrations in the slab, don’t worry just get them in, and run a spare just in case. 

Yes, I'm expecting this as part of the architect's work but I just want to make sure I'm happy in my own mind before him and the builder start trying to bamboozle me!

 

Good point ref power for the sewage - had missed that one.

[Bancroft]

18 hours ago, Andehh said:

Do not forget insulation size on the pipes!!

Good point.  I expect size of duct is a balance between being as small as possible to reduce space and any heat loss, but big enough to not make it impossible to thread stuff through.

[Bancroft]

15 hours ago, Nickfromwales said:

he last M&E spec I delivered had about 17 different ducts for everything

Now got me thinking about what I might have missed!  My list seems small in comparison.

[Bancroft]

Some really helpful stuff here, gents, many thanks.

 

Feel better equipped to hold my own with the professionals.

[Russell griffiths]

List from my memory 

power in

power out to garage

power out to sewage plant

power in from solar

power out to car charger

telecoms in

cat 6 out to electric gates

power out to electric gates

cat 6 out for cameras 

power out front garden lights

power out back garden lights 

ASHP flow out

ashp flow return, could both be in single insulated duct

power to ASHP 

cat 6 to ASHP 

 

so 13-14 ish without thinking too hard. 
plus all your poo pipes. 
 

lots could change in your situation, 

sewage plant might be near the garage so could take power from there, the car charger could be on the side of the garage as well. 

[Nickfromwales]

12 hours ago, Bancroft said:

Yes, I'm expecting this as part of the architect's work but I just want to make sure I'm happy in my own mind before him and the builder start trying to bamboozle me!

The only real issue with rising penetrations through a slab is if it’s a block and beam. In this situation you need to avoid a beam. 

Structural engineers will have some “say” if you have all ducts together and it requires steel reinforcements being re-jigged, but a little bit of pragmatic pre-planning and dialogue will resolve this in a day. 

Tell your builder that this will progress at your pace, and will arrive at the end result that you want, and he will have to slow down accordingly. 

[trialuser]

My advice is that you talk to your air con installer at an early stage.

You will need to use an f-gas bod.

There are restrictions on the max pipework length to each indoor unit.

The insulated pipes (a pair to every indoor unit) are quite bulky, easily kinked, the insulation is easily torn (and then at risk of condensation forming) and should be a continuous length from external unit to the internal units.