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Retaining wall against garage and drainage

eandccollinseandccollins Posts: 5
in Garden design

Hi,

I am in a new build and have a sloping garden. I have a gardener who has leveled it into 2 levels and put in a retaining wall, made out of sleepers screwed together and placed on concrete, across the  whole garden and also behind/against the garage wall.

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For damp proofing, he has put 2 strips of plastic in between the garage and the sleepers....not much room for anything else. You can see the plastic sticking out of the right hand side.

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He plans to put drainage behind the length of the retaining wall and feed it into the drain at the end of the garage.

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Is this all ok?I've a nasty feeling that

1.there needs to be a larger gap between the garage wall and retaining sleeper wall and

2. the damp course/plastic sheet needs to go under the concrete, up the wall and stick out of the top of the sleepers

Also, he's put sleepers against my neighbours garage with no plastic sheet at allimage, stood on concrete.... is this ok? I thought we needed gravel then the wall?

....advice please as I'm worried he's botching it all up....pics to follow.... Thanks for any help!

Posts

  • LoxleyLoxley Posts: 5,398

    I think he should have left a 1ft gap. Even where he's put the membrane, water will be able to get behind the top sleeper and then behind the membrane. What does he plan on doing around the downpipe?

  • eandccollinseandccollins Posts: 5

    nothing ....as far as i know he was going to connect the new drain from behind the sleepers to that drain but don't know how

  • eandccollinseandccollins Posts: 5

    should the membrane go under and also over the top of the sleepers too instead of just behind...?

  • raisingirlraisingirl Posts: 6,885

    Does the garage - yours or your neighbour's - have a damp proof course? If yes and if you stick to Plan A, you need your new dpc to overlap with the existing one and the two strips will need to be very well taped together so water doesn't seep between them. Done as he has, the sleepers are on the damp side of the membrane. Water in the soil will soak into the wood but won't get to the wall beyond. Assuming water can't get through, the main problem will be the sleepers are likely to rot because the moisture will sit between them and the membrane with nowhere to evaporate away. 

    If the garages don't have dpcs, then the membrane is fairly pointless. Water will just pass underneath the bottom and soak into the wall

    A gap would be far more sensible - then the no dpc situation is as it was when the garage was built - no better no worse, and in the dpc case the sleepers will last a lot longer.

    As an aside, it is generally not permitted to connect a land drain into the sewers. So unless your rwp goes to a soakaway on your own land, he really shouldn't do that, at least not without building control/water authority permission

    “It's still magic even if you know how it's done.” 
  • eandccollinseandccollins Posts: 5

    Thanks for your advice. ...yes the damp course is there on both garages.  But I think a gap is best too.... plus he's not put any membrane on the neighbours side......looks like we'll have to take it all up....

  • eandccollinseandccollins Posts: 5

    Thanks for your advice. ...yes the damp course is there on both garages.  But I think a gap is best too.... plus he's not put any membrane on the neighbours side......looks like we'll have to take it all up.... start again

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