building a 3-courses brick retaining wall - foundation?

Discussion in 'Landscaping and Outdoors' started by SpaceTofu, Jun 11, 2017.

  1. SpaceTofu

    SpaceTofu Member

    I am seeking an advice; my partner and I are in the process of starting to build a patio and we realised the slope is a bit too step as it is, hence we would like to build a small 3 courses brick wall to flatten it out (it would still retain a bit of a slope to help water flow).

    The soil is very clay-ish and we were wondering whether we should lay a concrete base or whether compacted type-1 aggregate and sand would be OK too?
    If the concrete base is a must, would you recommend that we lay a base of type-q aggregate and sand nonetheless, to avoid the cracking of the concrete down the line?

    Here is a visual (Fig. 9) that pretty much matches our situation (image courtesy of Wickes)

    [​IMG]
    I should probably mention that we are more than happy to skip the concrete bit, both so we do not have to deal with the cement mess and so that we do not entrench our soil with a massive concrete slab.

    Thank you!
     
    Last edited: Jun 11, 2017
  2. WillyEckerslike

    WillyEckerslike Screwfix Select

    There are a couple of things to consider here. As your soil is clayish, it will swell and shrink when wet or dry so you need to have a concrete footing to counteract that movement but....
    As you only need a 225mm high wall, is there an opportunity to simply cut and fill the ground under your planned patio? This means digging the ground that's high and placing it where it's low to 'level' the ground up - you still need a fall of about 1:80 to shed rainwater. Is there room to let the land drop away beyond the patio? Depending on your choice of finished surface you may also need compacted stone underneath which can also be used to correct the levels.
    Google 'cut and fill' to see what I mean. By the way - the Wickes drawings don't show any of the footings as wide enough - should be twice the width of the wall.
     
  3. Tricky Dicky

    Tricky Dicky Screwfix Select

  4. KIAB

    KIAB Super Member

    Gabion cages.
     
  5. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Hollow 18x9 blocks. Plant fings in 'em as well.
     
  6. SpaceTofu

    SpaceTofu Member

    Thanks for all of your suggestions (Gabion cages, hollow bricks and railway sleepers) but if we were to build a retain wall, we'd like the look of bricks.

    I googled and very interesting reading, thank you.
    If I get what you mean, do you suggest for us to excavate the slopey bit of soil close to the house (in green) so that then the patio level is "naturally" flat (we still would put aggregate and sand of course) and take the excavated bit and put it at the end of the patio area so to have a "natural" heap of soil retaining the patio as opposed to building a wall of bricks?

    [​IMG]

    It is definitely an option I believe
     
  7. WillyEckerslike

    WillyEckerslike Screwfix Select

    That is the gist of what I meant and might possibly mean less digging than properly excavated footings! You will need the fill to extend beyond the patio because you need sufficient soil to simply 'stay put' (a non-technical term) so save your topsoil for this and use subsoil for the fill if possible. The resultant bank/slope beyond the patio can be planted or turfed (if it wont be too difficult to maintain) and either will help to stabilise the soil.

    Whatever you choose to do, it will be essential that you fully compact the fill ('cut and fill' or behind a new wall) otherwise it will settle over time and spoil the patio. If you use the cut and fill approach and given that it is a clayish soil you might need to add some concreting sand to fill the inevitable voids that will occur - not a problem with proper hardcore/MOT Type 1 as they have a mix of 'fines' to compact evenly.

    Good luck with it.
     
  8. SpaceTofu

    SpaceTofu Member

    Thank you Willy.
    It is definitely an interesting approach; interestingly though we started looking at pictures online of patio bordered by railway sleepers and we will possibly go down this route, seeing also that there is a supplier close to our place.
    Thank you for all your inputs!
     

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