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    • CommentAuthorgoodevans
    • CommentTimeOct 28th 2017
     
    I will end up with 110mm drain pipes laid to minimal fall in the main slab - I will be wanting to connect 40mm bathroom sink and shower drains that are directly above that pipe - is it acceptable to connect each of those 40mm pipes with a solvent welded boss junction from the top (or near the top) - or should I use a 40 to 110 adaptor and then connect with a 110/110 junction.

    should the 110 pipe in the slab be orange/brown - or gray/black or does it not matter?
    • CommentAuthorMike1
    • CommentTimeOct 28th 2017 edited
     
    For all below ground drainage the minimum pipe diameter is 75mm, but 100mm is more common. You'll need a 75 or 100mm branch off the main pipe up to the floor surface and make your 40mm connection there.

    Note that foul drains must be laid to at least 1:40 to be legal - not sure if that's what you mean by 'minimal'. Since you're bedding the pipe in concrete you'll need to wrap the joints in polythene and extra measures are also required where the pipes pass through walls. Also follow any other pipe manufacturer's recommendations. And make sure the pipes stay put when you place the concrete. Personally I prefer clay below ground...

    Colour not important, provided you avoid blue, red, yellow and other colours normally reserved for other services.
  1.  
    I thought that grey was for above ground and orange was for below ground (in ground)
    • CommentAuthortony
    • CommentTimeOct 28th 2017
     
    I would like r0dding access too, if not then this kind of thing might help https://www.plastics-express.co.uk/underground-drainage/Underground-Drainage-110mm/110mm-adaptor-to-waste-pipe-p-pte334?kw=pla-106194235290+c&fl=1000&ci=43648356210&network=pla&gclid=Cj0KCQjw1dDPBRC_ARIsAJZrQfrB83-boT8y9LufGOb-d7QZjAUWmrq95KuEGY9RSYcqmRivDPbypFsaAqaXEALw_wcB

    Technically if you combine two waste pipes then they should be into 50mm tee then into 110mm drain

    Double 40 or 50mm branch might do it or a soil manifold
    • CommentAuthorgoodevans
    • CommentTimeOct 28th 2017
     
    Ok - my thinking is that the drain at this point can be considered to be more 'inside' the house than outside so I was thinking 18mm fall per meter as per table 2 of the part H guidance (this is a fall of 1:55 - why the guidence swaps between Xmm in 1m internal and 1:X gradient external I don't know). Once the pipe breaks outside of the slab I will use settlement connectors to go into ground drainage proper.

    The RC ground slab and ring beams are 'warm', suspended on piles and unventilated by virtu of using cellcore from Cordek.

    However because of the diameter of 110mm pipe the detail wherever this pipe is required is a little more complicated because I have to drop the level of the insulation to accommodate - However 40mm pipes can be laid in the screed, or between the reinforcement in the slab - the detail here is easier - but when I reach the 110mm drain below I wish to connect to the drain here.

    (for the kitchen/utility - I will use a gully because of the potential of fat deposits). I know 40mm pipe is regularly laid in screed and presumably it is not is not considered 'external'.

    I'm floundering here - I simply don't know what I don't know - and the regs don't seem to cover my situation.
    • CommentAuthorMike1
    • CommentTimeOct 28th 2017
     
    Posted By: Peter_in_HungaryI thought that grey was for above ground and orange was for below ground (in ground)

    In general plastic underground is terracotta-ish in imitation of clayware, with white or grey above - sometimes black - but maybe there are exceptions out there. The important thing is to get the correct pipe for the purpose - you certainly can't use pipes intended for above ground use below ground.
    • CommentAuthorgoodevans
    • CommentTimeOct 28th 2017
     
    But are pipes in screed (or rc slab immediately below that screed) above or below ground? For me ground level may be another 500mm below my pipes.
    • CommentAuthortony
    • CommentTimeOct 28th 2017
     
    Plastic Drain pipes in the ground need to be thicker walled to protect from ground pressure and in ground loads
    •  
      CommentAuthordjh
    • CommentTimeOct 29th 2017 edited
     
    The notion of my drains running vertically through the slab gave me enough concern, I'd hate to have horizontal drains actually embedded in the slab. Could you put the drain inside a duct so it would be possible to repair it at a later date without digging up the slab? Also, and just to be sure, have you checked with your SE since the drain will significantly weaken the slab?

    Note that the mode of operation of Cellcore is that if heave occurs, the Cellcore is crushed. If the heave subsequently retreats, the Cellcore does not expand again; instead a void is left. I don't know if that would affect anything in your case.

    edite: Oh, and what Tony said about rodding access.
    • CommentAuthorgoodevans
    • CommentTimeOct 29th 2017
     
    Yes I'm aware that the cellcore will leave fins on the ground after a heave event - but I will have another 200mm of eps above that and any void left will be unventilated. The eps layer and fins will be bonded to each other and to the RC slab so it should behave like EWI should a heave occur. (but better because the ground will be warmer and the wind almost zero).

    Strength wise the SE was comfortable that the centre of the slab is not 'used' so a small pipe between the top and bottom reinforcement is ok, also ok is larger pipe 110mm through the centre of ring beams (A pipe this size would sit in its own pocket of concrete under the slab. A pipe located here would be stable, not subject to movement and provided it doesn't rot should last the lifetime of the building.

    Taking the stack vertically into the ground however means I have to accommodate heave/shrinkage at this point - using a larger duct (e.g. 160mm pipe) doesn't help as this also needs to accommodate movement at entry to the slab. I'm between a rock and a hard place (or more precisely concrete and moving soil).

    It also strikes me that although the building structure has to allow up to 150mm of heave - the gas/water/electricity cables seem to rely on enclosed pea gravel to provide stress relief to connections!
    • CommentAuthorMike1
    • CommentTimeOct 29th 2017 edited
     
    IMHO you should build the vertical and horizontal pipes into the slab (thickening the slab down and around it as required) and make provision for movement through the foundations using rocker pipes designed to accommodate the amount of movement expected.
    • CommentAuthorgoodevans
    • CommentTimeOct 30th 2017
     
    Yes Mike - that where I've got to and where I stated at the original post.

    But is it also the consensus here that "All pipes in screed or below must be 110 orange drains - no exceptions. In other words a 32/40mm pipe from a washbasin or shower must be adapted to 110mm immediately it reaches the screed - it may not be embedded in screed/slab then connected to a 110mm horizontal drain that happens to be passing nearby (or immediately underneath) within the slab." I ask because I can route the smaller pipes without disturbing the insulation / slab detail.
    •  
      CommentAuthorfostertom
    • CommentTimeOct 30th 2017
     
    Posted By: Mike1The important thing is to get the correct pipe for the purpose - you certainly can't use pipes intended for above ground use below ground.
    And I believe the terracotta ones don't have UV resistance for above ground use.
    • CommentAuthorgoodevans
    • CommentTimeOct 30th 2017
     
    Thanks FT - but I have no intention of using orange/terracotta/brown above ground. but I'd like your opinion on white waste pipe 32/40mm in the screed and its connection to horizontal drains.
    •  
      CommentAuthordjh
    • CommentTimeOct 30th 2017
     
    Posted By: fostertomAnd I believe the terracotta ones don't have UV resistance for above ground use.

    Eh, terracotta doesn't have UV resistance? Why has it been used for roof tiles for thousands of years then? Terracotta is one of the most stable substances known to man.
    • CommentAuthortony
    • CommentTimeOct 30th 2017
     
    He means terracotta coloured plastic pipes of course
    •  
      CommentAuthorfostertom
    • CommentTimeOct 30th 2017
     
    Of course!
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