I'm going to building a retaining wall to level my garden. The wall is not touching the house, I'm trying to work out the drainage solutions for this wall. Its not going to be too dissimilar from the image below.

The lower section (below the DPC) will be double skinned engineering bricks. Above the DPC will be concrete blocks laid flat and then the blocks will be rendered. On the image, they suggest using copper pipe, however, are there any other options for this? I didn't want to use copper pipe as I would prefer something that looks a bit better, such as a standard weep vent, but I can't see any that are deep enough for the two layers of bricks (and bricks will be offset from each other anyway)

What other options are there?

enter image description here

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    It's opinion, of course, and you're entitled to yours, but copper usually looks pretty classy. You can get coatings on them so the remain copper colored instead of tarnishing to green right away. Additionally, with a pipe, you can stick a pipe cleaner of sorts in there to clean it out once a year, as opposed to simply leaving the mortar out of a joint as your weep space - once it's clogged, there's no easy way to clean it out.
    – FreeMan
    Commented Jan 16, 2023 at 13:43
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    Why do you need a DPC in an outdoor garden retaining wall? Commented Jan 16, 2023 at 17:36
  • The copper would (could) be cut off flush anyway. You wouldn't really even see it.
    – isherwood
    Commented Jun 15, 2023 at 16:21

1 Answer 1


That looks like a good start to me.

Your weep holes look a bit small. Also, do you have a way to daylight your drain?

You'll want a way to erosion-proof the surface near the back of the wall (turf grass may be sufficient), and have a way to drain that (slope to either end of wall). I'd consider backpitching the surface a short distance behind the wall to create a small swale, and not have water against the back of the wall.

Make sure there's enough topsoil above the gravel. You may also want to reconsider the pea gravel if there's traffic above. It squishes instead of interlocking like angular gravel.

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