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Yes, another question about garden retaining walls....

Discussion in 'Building' started by hobboman, 19 Feb 2021.

  1. hobboman

    hobboman

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    Sorry if this one has been asked elsewhere, but I haven't been able to find a clear answer. I'm building a garden retaining wall across a sloping plot, about 1m high, about 7m long, and with a 2m length return back into the slope. I'm planning to use concrete blocks laid on side with expanded metal lath for extra strength and then face the block wall with a local stone wall using 140mm coursed split face. The back of the block wall will be infilled with 20mm pea gravel, and the whole thing will retain a patio onto which a concrete slab and summerhouse will be built. 2 questions:

    1) Do I need to put DPM on the back of the blockwork? I'm not clear whether it's better to protect the blockwork from damp with DPM, or if by using it I'm effectively creating a dam, albeit with the usual drainage holes in the wall.

    2) Is there any merit in leaving a cavity between the block wall and the decorative stone facing wall? If so, presumably I'll need to tie the 2 walls together, or should I do that anyway even if I build without a cavity?

    Thanks in advance for any advice,

    Mike
     
  2. ^woody^

    ^woody^

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    Yes its best to keep the wall dry from the ground behind it. No cavity. The rear should be drained vie a land drain or weep holes in the wall
     
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  4. hobboman

    hobboman

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    Cheers Woody, I'll put some DPM on the shopping list....
     
  5. 5teves

    5teves

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    I did something similar once for a freind, and we did include dpm.

    Doesn't cost much and gives the added assurance even if nots a absolute requirement.
     
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  7. hobboman

    hobboman

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    Thanks 5steves, all ordered and underway from week after next.....
     
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