Building a retaining wall

17 Dec 2008
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United Kingdom
Hi all,

want to build a retaining wall in the garden, approx 3ft high by 20ft in length. It will act as a retainer as the earth the other side of it is sloping/ push down from the woodland above it.
We'll back fill soil to the top of the wall and plant flower beds (well the mrs will :)).
Question is, will regular breeze blocks do it or would i need some of the hollow breeze blocks that can then be filled with concrete to reinforce the wall. Or maybe some of these interspaced to add strength without going overboad.
Was thinking a 450mm footing would be ok (i guess that depends on the type of earth?)

Any help appreciated, thanks
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I would say that 3ft high block on flat would be ok, as long as it does't slope too badly upwards.

As for a footing 450 wide would be ok, but you need to make sure you go down to the proper depth, its going to need to be capable of supporting that wall. I would imaging a minimum of 600mm but would probably be aiming for 1 mtr.

Make sure you allow for weep holes there will be a lot of moisture build up behind the wall.
1m for a 0.9m wall? :eek:

The wall is only retaining an approximate 45° slice of earth from about 300mm up from the lower ground level

A foundation down the good ground, and then a further 150-200mm would normally suffice 600mm normally

I'd say 450mm wide would be OK too

Normal concrete aggregate blocks will be fine. 3.5N will do, but you might find that the face is a bit rough, so 7N may look better

You could build the bottom two courses double thickness and the top two single if you like
Thanks fellas.
Actually i originally meant a footing 'depth' of 450mm, I was thinking of going 300mm wide, as the blocks are 100mm wide.
Woody if you reckon a double skin at the bottom would be better, i'll go 450mm wide.
Really didn't think i'd have to go as far down as 600mm, but will if necessary.

We may willow screen or put half round post on the face of the blocks, so smoothness isn't an issue.

Thanks again. :)
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Kjacko, you should be aiming to be alot wider on your foundation than 300mm, retaining wall foundations are designed to resist rotation as well as material load from the actual wall. I would go for around 600mm wide and sit the actual wall towards the rear of the foundation. Depth wise will be determined by ground conditions but if you are into a good base 450mm deep will do.
And as said by others, pay attention to drainage behind your wall.
Thanks fellas.

Differing opinions there, but certainly something to think about though

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