Rebuilding a 2ft garden retaining wall

May 20, 2014 11 Replies

Hi-



I'm finally getting round to the garden, which is on 2 levels, about 2 foot apart, separated by a stairway and a retaining wall that has collapsed.



I want to rebuild the 2 foot high retaining wall.



I obviously need to read up about it. Can anyone please suggest any relevant links?



Alternatively, please add to this thread.



Thanks :)



C

Can you get the old mortar off the bricks? If so, just relay them. Might be an idea to backfill with rubble and leave some gaps for drainage

Dry system (no mortar):

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?

Wickes sell it and it can be obtained on the internet by the pallet.

Still needs a foundation (tamped MOT Type 1 if following the instructions) but has the advantage that it will move if the round moves.

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I built a 1/2 brick thick retaining wall out of engineering brick in a Flemish bond, but with the cross bricks removed to leave drainage holes which we planted up with drought tolerant plants. So:

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without the black bricks. That did use mortar. I built a bit of a foundation first, but it wasn't very much.

The wall was about 1m high, and sloped back about 100 or 200mm.

Isn't it traditional not to put proper foundations in, then complain that the wall has failed after a comparatively short time? Indeed, it may be more cost/labour effective to keep rebuilding the wall than to put in proper foundations that probably need to go down the best part of a metre to work properly.

I didn't bother.

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This was built on slabs over dry mix and MOT type 1, reclaimed soft red brick with cobble top. The back was reinforced with a sloping, stiff concrete mix extending a few inches below the slabs. Hasn't moved yet although I suppose the curve is stronger than a straight wall would be.

A metre! Good grief. My foundations were no more than a spade's-depth, probably half that. The wall was fine for the ?five? years we stayed there.

The curve will be *much* stronger. Also the OP wanted a wall about twice as high as yours - which means it will be under at least twice as much stress, probably four times, and it might even by eight times.

Half way down a wall which is twice as high, the sideways pressure from the soil will be doubled, but the distance above the bottom will be double too, so the torque to topple the wall over (which is simplest failure mode) will be quadrupled. I think I'm convinced it's a square law.

Okay, and that is a really, really small wall. More of a wallette, really.

We have a 5 foot, or so, retaining wall at my old office. I remember it being replaced when I was a child, and I had it replaced when I was 35. A surveyor friend said that to work properly with that sort of pressure of earth we needed to treat it like a house wall and go down around a metre with the foundations - 90cm maybe? Maybe that was overkill, but I am 60 now, and the wall is looking absolutely fine. It looks a good deal better than the poor builder did when he was digging the foundations.

But it's very nicely done, I should have said!

In message , Martin Bonner writes

Looking over a house for sale with some friends.

Casually slammed shut the gate on the way out and the 4' single brick (or is it half?) wall fell over!

Clearly built in a hurry for the impending sale. There was a pier at the gate but the builder had incorporated a plastic dpc......

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