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Sinking posts next to wall

  • 17-07-2022 11:18am
    Registered Users Posts: 636 ✭✭✭ RainInSummer


    I have a small retaining wall, approx 18 inches high that I'd like to sink three 6 inch beams as close as possible to. As in almost touching.

    I'm guessing as it's a retaining wall it's got some kind of decent foundation. Any issues digging down through it for those small sections?

    Would be going down about 36 inches.


  • Registered Users Posts: 3,637 ✭✭✭ policarp

    Unless they are more than 4 or 5 foot tall

    why not fix them to the retaining wall?

  • Registered Users Posts: 636 ✭✭✭ RainInSummer


    Apologies, I should have stated that they will be 8/9 feet tall.

    The posts will be used to attach a hit and miss fence that could have potentially a high wind load and would be too tall I reckon.

  • Registered Users Posts: 4,229 ✭✭✭ 10-10-20

    Yes, a retaining wall will most likely have a footing unless it's an engineered wall (such as a cantilever or piled wall). How extensive that is all depends on the structure. Best excavate downwards and review. Attaching the posts to the wall is going to place both the retained earth pressure and the wind load on the wall, so I understand your desire to have ground support for the posts.

    You could remove a small section of the footing and perhaps re-concrete it back around the posts afterwards, but that all depends on the design and criticality.

  • Registered Users Posts: 30,750 ✭✭✭✭ Lumen

    I'd be inclined to use bolt down post shoes on the basis that you won't suffer rotting posts.

    Do whatever is required to extend the footings out and up (properly tied in to the existing footings) to provide a stable base you can bolt into.

  • Registered Users Posts: 636 ✭✭✭ RainInSummer

    Can you get 6x6 shoes? I've used 4x4 in the past and they are grand.

    Was hoping to only pour a light enough slab as there won't be huge weight on it, maybe going 3" instead of 4. The plan was to sink the posts just past the edges of the slab where the slab and wall meet. I'll cobble something up with the suggestions here though, cheers.

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  • Registered Users Posts: 636 ✭✭✭ RainInSummer


    Would certainly save a lot of digging...