Drainage/waste pipe depths

[Vijay]

top of foundation is 750 below FFL or 600 below FGL

[Vijay]

13 hours ago, PeterW said:

It is if you sleeve it or do the detail properly...

 

what depth are the top of your foundations below finished ground level ..?

Hi Peter,

 

Is there a special sleeve to run PVC pipe through concrete footings?  A quick look on Google suggested you shutter up around the pipe with a lintel on the top?

 

So is it perfectly normal to run a PVC pipe though concrete foundations or should it be avoided if possible?

 

Also, am I right in saying that every join where say 2 toilets run into 1 pipe, should have an inspection chamber/rodding point and not just an 45 degree 3 way junction like this?

 

Edited April 7, 2017 by Vijay

[Ian]

29 minutes ago, Vijay said:

Hi Peter,

 

Is there a special sleeve to run PVC pipe through concrete footings?  A quick look on Google suggested you shutter up around the pipe with a lintel on the top?

 

@Vijay

The normal way to do it is to put a lintel in the wall of the footing and use a short section of pipe with a joint each side for the part where the pipe goes through the wall.

 

32 minutes ago, Vijay said:

So is it perfectly normal to run a PVC pipe though concrete foundations or should it be avoided if possible?

 

Going through the wall footing (using a lintel) is normal but not through the actual concrete of the foundation itself or below it.

[Ian]

36 minutes ago, Vijay said:

Also, am I right in saying that every join where say 2 toilets run into 1 pipe, should have an inspection chamber/rodding point and not just an 45 degree 3 way junction like this?

 

It depends where you are in the UK.

In England & Wales BCOs usually like to see an inspection chamber or at least rodding access at these type of junctions.

 

In Scotland the building regs take a slightly different view - for example BCOs there don't like any manholes inside the footprint of the building (outside the building is ok).

[Vijay]

25 minutes ago, Ian said:

@Vijay

The normal way to do it is to put a lintel in the wall of the footing and use a short section of pipe with a joint each side for the part where the pipe goes through the wall.

 

Going through the wall footing (using a lintel) is normal but not through the actual concrete of the foundation itself or below it.

Is that to create a movement joint? I'm surprised there isn't some sort of support sleeve to use instead of a lintel though.

 

If I'm not supposed to go through the concrete foundation itself, how would I get the fall on the pipework?

[Ian]

19 minutes ago, Vijay said:

Is that to create a movement joint? I'm surprised there isn't some sort of support sleeve to use instead of a lintel though.

 

@Vijay

Pages 20 & 21 of this NHBC Foundation design document is a decent guide to the detail you need:

http://www.home-extension.co.uk/nhbc foundation guide.pdf

Yes, the joints and the lintel are to allow for movement. They are there to minimise risk of the pipe breaking.

 

19 minutes ago, Vijay said:

If I'm not supposed to go through the concrete foundation itself, how would I get the fall on the pipework?

Have you built the foundations already?

If you haven't already built them then the usual approach is that you locally set the depth of the foundation to suit the drain depth. Normally foundation depth isn't a problem unless you have a long internal run of pipe before you get to the external wall (eg a WC positioned in the middle of the house plan). The alternative approach if your WC is on an external wall is to take the drain through the wall above ground to an external soil stack but that can bring extra issues re air tightness unless you plan carefully for it.

Edited April 7, 2017 by Ian

[Vijay]

Cheers Ian, that's a really useful guide.

 

The foundations aren't concreted yet but it would be a pain to dig down further and cost around an extra 3k. My builder mate reckons it's no problem to have waste pipes in the concrete as long as they are boxed with something like clayboard and support over with a lintel (as I'm using ICF I would just add rebar). I'm going to call the BCO tomorrow to check

[Vijay]

Finally got to speak to a very friendly BCO today and he's more than happy for the drainage to be within the foundations, as long as movement is taken into account, so either a movement joint or as my builder mate suggested, the pipe boxed with something like clayboard. Also to use a lintel above it but I will add rebar as I'm using ICF