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Garden wall

dmoblaydmoblay Posts: 14
in Garden design
I’m planning to replace the fence across the back of my garden and down the side with a 2m high wall.

im going to build from concrete blocks laid flat to provide suitable depth and strength to the wall.

the foundations will be 450mm wide (twice the block width) but I’m unsure about how deep to go on the foundations.

the soil has clay in it and there are also some decent sized trees in the neighbours garden. The ones to the back are about 1-5m from the wall.

height wise I would guess they are 25-30ft high.

i was intending to dig the foundations to 500mm - will this be enough? 
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Posts

  • K67K67 Posts: 2,506
    edited May 2020
    The norm for foundations is down to firm ground
    https://www.mybuilder.com/questions/v/2300/depth-of-foudations-for-a-7ft-wall
    https://www.diy.com/ideas-advice/how-to-lay-the-foundations-for-a-garden-wall/CC_npci_100135.art
  • ThebigeasyThebigeasy Posts: 190
    edited May 2020
    Down to solid ground, with a 2m wall the foundation will need adequte frost protection of about 450mm. 
  • dmoblaydmoblay Posts: 14
    Thank you. What do you mean by adequate frost protection? Do you mean from the foundations? 
  • ThebigeasyThebigeasy Posts: 190
    450mm below ground level to protect the foundation from frost, seen walls collapse over time due to this. 
  • wild edgeswild edges Posts: 10,497
    How long is the wall? If you have a length over 7 metres you might need to consider expansion joints and possibly a pier or 2 for stability. I'd be tempted to lay it with blocks on edge and use piers rather than on flat which would be a big saving in materials. How will you be facing the wall off?
    If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
  • dmoblaydmoblay Posts: 14
    wild edges said:
    How long is the wall? If you have a length over 7 metres you might need to consider expansion joints and possibly a pier or 2 for stability. I'd be tempted to lay it with blocks on edge and use piers rather than on flat which would be a big saving in materials. How will you be facing the wall off?
    Thanks. It’s 10m long. If I lay vertically I’d need to do a second skin as the wall is 2m high. I can’t build in pillars as it does t fit with the rest of the look and space in the garden. 
  • dmoblaydmoblay Posts: 14
    Thebigeasy said:
    450mm below ground level to protect the foundation from frost, seen walls collapse over time due to this. 
    Thanks. I’m thinking I’ll make the slab 450mm deep, but, allow for a course of bricks below ground level as well.  Would that suffice? What about tree roots? Will a slab that thick and deep withstand tree roots? 
  • LoxleyLoxley Posts: 5,698
    dmoblay said:
    wild edges said:
    How long is the wall? If you have a length over 7 metres you might need to consider expansion joints and possibly a pier or 2 for stability. I'd be tempted to lay it with blocks on edge and use piers rather than on flat which would be a big saving in materials. How will you be facing the wall off?
    Thanks. It’s 10m long. If I lay vertically I’d need to do a second skin as the wall is 2m high. I can’t build in pillars as it does t fit with the rest of the look and space in the garden. 
    Remember you can offset the piers to one side or the other

    See the source image


    "What is hateful to you, do not do to your neighbour". 
  • owd potterowd potter Posts: 979
    edited May 2020
    dmoblay said:

    Thanks. I’m thinking I’ll make the slab 450mm deep, but, allow for a course of bricks below ground level as well.  Would that suffice? What about tree roots? Will a slab that thick and deep withstand tree roots? 
    Slab?, I presume you are referring to a strip foundation beneath your wall?
    Reinforce your foundation with a layer of A142 mesh or such which will strengthen against most root problems
    Just another day at the plant...
  • wild edgeswild edges Posts: 10,497
    That would be a lot of mesh to cut for a 10m wall. I'd say you need to dig down below the root level and just use a root barrier where the problem areas are.
    If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
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