1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Core drilling below extension - is a lintel required

Discussion in 'Building' started by SimonSnake, 16 Aug 2015.

  1. SimonSnake

    SimonSnake

    Joined:
    14 Nov 2012
    Messages:
    10
    Thanks Received:
    0
    Location:
    Hampshire
    Country:
    United Kingdom
    Hi.

    I'm building a new extension, but that bit is not relevant to this query, other than stating we wish to relocate all the waste water and foul water out of the existing bungalow into a new inspection chamber because the old chamber is slap bang in the middle of where the new extension is going.

    Also, some information to help one of you experts to answer my query:

    It is a bungalow, built approx 1929 to 1930.
    It has suspended wooden floors above concrete sub-floors.
    The kitchen (2m wide) sticks out 3m from the rear of the bungalow.
    A utility area, approx. 1.5m deep was built some time in the past at the end of the kitchen.
    A patio, approx 1m was beyond the utility area, now dug out.
    Approximately 1.5m from the rear of the utility area is the main 6" clay lateral drain (public sewer) running through the rear garden parallel to the back wall of the bungalow.
    I'm going to be installing a new round plastic inspection chamber between the outer wall of the utility area and the public sewer.

    What I've done:

    Upon excavating ground level outside (revealing a break in the private surface drain just as it joins to the public sewer - imminently being fixed), I exposed the side of the foundations of the utility area.
    From inside the bungalow, using a core drill with a 117mm core on it, I have drilled through the cavity wall at the rear of the kitchen, below the wooden floor about 20 to 30cms above the subfloor, sloping down at approx 2.5° from horizontal, then excavated the clay soil for an additional 1.2m under the slab that makes the floor of the utility area, met tough foundation blocks, purchased several 20cm extension bars for the core drill, then core drilled through the block to the outside.

    When building our new extension, we had to pour the strip foundations approx. 150mm either side of this public sewer by way of shuttering and filling with pea shingle after removing the shuttering, and this has to be topped with a lintel, so I understand protecting pipes with a lintel above.

    Observations:

    When watching videos etc. showing people using core drills to go through walls, either external cavity or internal single skin ones, to put soil pipe though, they do not appear to require or put in lintels above the pipe to protect it from any movement above.

    Diagram 7 in Approved Document H shows two pictures - one where no lintel is used and the pipe has flexible joints max 150 either side of the wall, and then a piece of pipe max length 600mm to another flexible joint. The other picture shows a much larger hole, around 50mm around the pipe with a lintel above.

    In our case, we have a cavity wall, 120cm of clay soil and a 100mm dense concrete block that have been cored through, a distance of around 1.5m. The only accessible areas are the inner skin of the cavity wall and, from outside, the dense block at the exposed end of the hole. The clay soil in between shouldn't move - it's only a small amount of clay soil under a concrete slab, so I'd hardly expect that to shift and squash the 110mm waste pipe.

    My question:

    So, I am asking if I need to cut out bricks/blocks to get lintels in to one or both skins of the cavity wall and at the dense block end, or does my cavity and the far dense block count as one long cavity so it means it would be easier to use the rocker pipe/flexible joint arrangement? (It would be easier to just use rocker pipes instead of installing 3 lintels.)

    I hope you understand all the above, if I haven't made it clear enough I don't know how else to describe it. I can take pictures if that helps.

    If all else fails, I'll have to contact our building control chap to get his views on what he thinks will be ok.

    Thanks, and I await your helpful replies.
     
  2. ^woody^

    ^woody^

    Joined:
    3 Sep 2006
    Messages:
    33,361
    Thanks Received:
    4,523
    Location:
    West Mids
    Country:
    United Kingdom
    I don't really understand any of that, but it looks like something to do with pipes going through walls?

    If so, above ground you don't need to allow for building movement, below ground you do. Lintels and gaps or fixed pipe and flexible joints.
     
    • Like Like x 1
  3. Sponsored Links
  4. Nige F

    Nige F

    Joined:
    28 Jun 2005
    Messages:
    21,178
    Thanks Received:
    1,732
    Country:
    United Kingdom
    Treat as one long cavity . If you use underground PVC orange pipe and fittings and a couple of Fernco bands for the flexibles, I'm sure that will be fine. Just run the type of pipe/flexi past the building inspector.
     
  5. SimonSnake

    SimonSnake

    Joined:
    14 Nov 2012
    Messages:
    10
    Thanks Received:
    0
    Location:
    Hampshire
    Country:
    United Kingdom
    So, that's one for lintels and one for flexible pipe joints. Anyone else able to put forward their views/thoughts?
     
  6. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
  7. Sponsored Links
Loading...

Share This Page