Retaining wall info needed

Discussion in 'Builders' Talk' started by LuckyPhil01, Jul 30, 2021.

  1. LuckyPhil01

    LuckyPhil01 New Member

    I am looking to make a retaining wall that is approx.10m long and 1.5m high.


    I would like to have a go at making this myself but it will be the first time laying blocks, I have recently renovated my property so fairly competent on the tools.
    Im not fussed about the looks of the Wall as I won't be seeing it (Wall would be retaining soil on one side, the step down leads into a field). I figured Concrete or breeze blocks would be the cheapest. is that right?..... Would anyone be able to advise on the size that the foundation should be (depth/width) and also the size of the blocks and which orientation they should be laid in- either laid flat so that the wall is thicker or conventionally?
    Would it be recommended to lay a perforated pipe along the wall? if so, what size and how many?
     
  2. Abrickie

    Abrickie Screwfix Select

    1.5 m high ? You would be requiring the services of a structural engineer ;)
     
    LuckyPhil01 and stevie22 like this.
  3. LuckyPhil01

    LuckyPhil01 New Member

    I see, well id build it as high as possible without needing a structural engineer
     
  4. Abrickie

    Abrickie Screwfix Select

    Lol, take your pick. NHBC recommend 600mm, LABC recommend 1m before SE
     
  5. LuckyPhil01

    LuckyPhil01 New Member

    60cm! WOW.......So, for the 1m wall, what bricks would you recommend? and can you advise me on the size of foundation needed? (depth/width) and also the size of the blocks and which orientation they should be laid in- either laid flat so that the wall is thicker or conventionally?
    Would you recommended to lay a perforated pipe along the wall? if so, what size and how many?
    Thanks
     
  6. stevie22

    stevie22 Screwfix Select

    If you need 1.5m then how are you going to get away with 0.6 or 1.0??????????

    Get an SE: it might be your child under it when it collapses.
     
    Abrickie likes this.
  7. LuckyPhil01

    LuckyPhil01 New Member

    not needing 1.5....was just a number I thought would be ok to keep the cows in the field and not in my garden ......Pretty sure 1m will do the job too :)
     
  8. Severntrent

    Severntrent Screwfix Select

    So assuming the wall foundations are set 500 in the ground is the wall 1000 or 1500 above field level
     
  9. LuckyPhil01

    LuckyPhil01 New Member

    If the foundation is 500 deep in the ground, then the wall would be 1000mm set on top.
     
  10. adgjl

    adgjl Active Member

    It depends on how heavy and determined the cattle are. A better bet might be a livestock Fencer to keep them away from your boundary, although you would obviously need the farmer’s permission for that option!
     
  11. stevie22

    stevie22 Screwfix Select

    Back up a bit: are we talking retaining wall which supports ground or a simple boundary wall to keep cows out of a garden??

    It would be the farmers responsibility to keep his cattle on his land.
     
  12. Severntrent

    Severntrent Screwfix Select

    Set on top of what, the foundation or the field ground level
     
  13. LuckyPhil01

    LuckyPhil01 New Member

    So my house is higher than the field...there is a 2m wide path on the side of the house next to this path there is a two step down, each step is around 500mm high and 500mm wide. at the bottom, there is a livestock Fence erected....Id like to remove the fence dig a trench, put in a foundation and then put a wall on top. Fill in the down steps to then have a 3m wide path.
     
  14. Severntrent

    Severntrent Screwfix Select

    OK here we go,

    So the actual height of the wall would be 1500mm, this is assuming that the foundation is 500mm below field GL which is an arbitrary figure as there is no info re your soil foundation properties i.e. if it was solid rock 100mm below field level then you would found your wall on this, if the ground is mush you may have to go deeper to put footings/foundations in all of which is another aspect of the intricacies of retaining wall design. Even though the wall would only appear to be retaining 1000mm of ground, retaining wall design does not allow for the fact that there would be 500mm of ground on the field side giving passive resistance to that side of the well hence wall height is taken as 1500mm (this I because the ground could be taken away or dry out and shrink away from the wall and thus any passive resistance would be removed)

    The simplest retaining wall design assumes that the weight of the wall resists the force of the soil acting on it and no tension develops at the base of the wall i.e the wall doesn’t lift off the ground and topple as a force is applied (imagine a brick being pushed with your finger and the front of the brick just lifting off the floor and the going over)

    Therefore based on the simplest method of wall design and assuming the retained material is cohesionless, would slope at an angle of 45 degrees if it was free standing, had a density of 1500kg/m3 and the wall is built out of bricks weighing 1800kg/m3 then your wall would need to be at least 570mm thick.

    A more involved analysis assuming the wall is stuck down onto the foundation ( mortar acting as a glue and a tension force allowed) would possibly reduce the thickness required to 300mm.

    Ultimately the retained soil may have a different density, a different angle of slope, be cohesive, have water contained in it and different brick densities may be used for construction all of which would change the results of the above design. And all this is before the actual foundation can be sized/designed!!

    As flagged up by others unless you have a wall less than 1m an SE input is definitely required and suffice to say no one on this forum can offer you any definitive advice re the design of your wall, unless its Mick the brick who has “always built walls like this sir and I have never had any problems”
     
    Jord86 likes this.

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice