Drains through walls

[WWilts]

How important is the BR 50mm gap all around the drain where it goes through a wall? Is anything less than 50mm seriously unsatisfactory for us to live in?

 

BR approved doc H 2.24, diagram 7b

 

 

Edited September 6, 2021 by WWilts
diagram

[MikeGrahamT21]

If its in the Building Regs, then it must be adhered to as far as I can say. I wouldn't risk it for something so minor really.

[WWilts]

3 minutes ago, MikeGrahamT21 said:

I wouldn't risk it for something so minor really

Trying to assess how hard to push the builder.
Lintelled opening 120mm for 110mm drain.
In other respects good builder, but is resistant to redoing the opening. No backfill around foundation masonry there, yet.

Edited September 6, 2021 by WWilts

[Moonshine]

what rigid sheet material would be used? does it mean to fill void (min 50mm) around pipe with compressible sealant, what product would be used?

[Nickfromwales]

Illbruck foam for the 50mm void, check different types for suitability. The website is quite helpful. 

Use cement backer board eg 12.5mm Hardi / similar as the closure plate. 

Edited September 6, 2021 by Nickfromwales

[Moonshine]

16 minutes ago, Nickfromwales said:

Illbruck foam for the 50mm void, check different types for suitability. The website is quite helpful. 

Use cement backer board eg 12.5mm Hardi / similar as the closure plate. 

 

cheers, it looks like its the FM330

 

https://www.illbruck.com/en_GB/product/fm330-pro-foam-air-seal/

[WWilts]

Thanks.
To push or not to push the builder re enlarging the space around pipe. Main consideration is whether the drains will function properly despite the narrower gap

[PeterW]

Drains will work fine but the BCO may say no …! Not that difficult to sort now, pain in the bum to sort when there are 7 courses of masonry on top. 

[WWilts]

Probably best to send the builder the BR text and diagram and leave it to him to decide next steps. Done that

[Nickfromwales]

1 hour ago, WWilts said:

Thanks.
To push or not to push the builder re enlarging the space around pipe. Main consideration is whether the drains will function properly despite the narrower gap

Do you understand why this gap is a requirement?

It is so that ground settlement / movement ( heave ) etc never affect the pipe. Pipes set in without have sheered in half because this has not been observed. It has zero to do with the functionality of the pipe, this is to ENSURE its longevity. 
Tell the builder this, and tell him to rectify. 

[WWilts]

Thanks. 120mm width of opening where 110mm drain will pass under lintel from underslab to exterior, while resting on/just above concrete footing.
Footing continues horizontally for 600mm external to wall. I suppose there will be a channel drilled into the concrete footing to form a haunch for the drain.

Still a risk of movement/pipe breakage? If so, can make an issue of it

Measured the openings under lintel, on either side of the partition wall. Left side 140mm, right side 170mm. 210mm would meet BR

Edited September 6, 2021 by WWilts

[Nickfromwales]

1 hour ago, WWilts said:

Still a risk of movement/pipe breakage? If so, can make an issue of it

That’s not for us to say   It’s your BCO who may fail it, so pass the onus on to the builder VIA EMAIL and state that “on his head be it should it not be passed”. Make sure he knows you will not be footing the bill for any such subsequent alterations to satisfy BCO. 

[WWilts]

Thanks, sent email with para 2.24 and diagram 7b of BR, AND mentioned the logic plus advice from "people who know". Incl suggestions re Hardieback board & Illbruck foam. Upon his head it is now