Proper drain for the made-up area with an extension

Discussion in 'Landscaping and Outdoors' started by dmr123, Sep 6, 2021.

  1. dmr123

    dmr123 New Member

    Dear All.

    We have moved into a house built in 1950ies (cavity wall).

    The house is situated on a slope down from the main road and that slope continues down into back garden. This house has a deep basement of 1.8m below the floor level. Looking inside it is dry. Vent bricks are all over the perimeter below DPC.

    In early 1970ies the previous owners build a living room and kitchen extension into back garden. Because of a slop down to the garden they firstly built a new made-up ground which is supported by a 1.6m-high wall in the garden. All this area was filled with the building rubbish like concrete blocks, whole bricks, etc. Then the extension was built.

    Above the building rubbish they filled-in a layer of about 20cm thick of red-coloured clay-ish soil mixed with large pebbles. This soil is very compacted and dense.

    On the top the area is covered with pawing slabs using mix-and-dab to form a patio zone. No visible drainage apart from one square drain for gutter.

    After some digging I discovered that extension foundation is about 0.6m deep of brick wall and then there is concrete footing (no idea how deep it goes) of 45-50cm wide (measuring from the wall).

    All the space above the footer is filled with building rubbish which is not compacted and has a lot of hollow spaces and cavities. And I can easily see water dripping there. It look like rain water can easily get through the top layer and then by cavities easily gets to the foundation.

    I am concerned about these cavities especially so close to the foundation and that rain can easily soak through the mentioned 20cm of top layer.

    What would be the best way to fix this to ensure that foundation is dry and to rain water is diverted away from the house to stop any potentian damage.

    I was considering installing a french drain, but there are a lot of confusing into online.

    Would appreciate help with my case.
  2. dmr123

    dmr123 New Member

    Please find a photo to support my post above.

    Attached Files:

  3. jonathanc

    jonathanc Screwfix Select

    If it’s been like that from the 70s without a problem I’d forget it. Time has given it a good test

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