Re: Building a retaining wall close to trees

Hello -

> > I'm planning to have a retaining wall built to hold back a 1 metre height > difference between two gardens, It will be built from blocks mortared > togther. I guess the concrete footings will extend about 1 metre below the > surface of the "low" garden. There are some trees within 30 cm of the > planned location of the wall, their trunk diameters range between about 5cm > and 20cm. I don't want to kill or substantially harm the trees. > > The builder I'm getting a quote from says he will put lintels into the wall > and footings so that roots larger than about 1cm in diameter don't have to > be cut. Is this a sensible approach, for the trees and/or the wall? > > Thanks

If you have roots which vary in diametre from 5cm to 20cm, and the builder 'accomodates' say, a 8cm root, will the 'accommodation' suffice when it gets to, oooh, say, 27cm?

So, I'll presume what the builder is hoping to be able to do is to create pillars of concrete on to which to rest the lintels; After all, I would think that there would be no point in putting concrete under a root. So, essentially, the wall would be built on a bridge of lintels? Sure would benefit drainage and therefore lessen the pressure on the wall to some extent.

And I'll assume that the idea will be to have, say 4 lintels abreast and in staggered formation: (like as in laying grass turfs) in order to limit the potential of the cracks which would most likely occur if they weren't laid thus.

A lot of trouble, and expense for a 1m high retaining wall. Why not go for a drystone wall? And whilst I think of it, I've seen this done (albeit only around 70cm high) with stkaes driven into the ground, leaning towards the bank of earth and wooden slates nailed inbetween.

Thanks for the comments. I think the wall needs to be a fairly substantial one, because there are buildings about 4 metres away on the high side. The height difference is currently retained by a wooden fence with 4" posts, but it is starting to lean over.

Does anyone have any comments on replacing the existing wooden fence with a fence using 5" concrete posts set in concrete, with concrete gravel boards to retain the soil. I think this is known as a "Berlin Wall" in the building trade. Hopefully it would be possible to position the posts so that they don't interfere with too many roots (there are only 4 trees along the 9 metre fence).

I think I'm going to get an engineer in to advise, but the idea of using concrete fence posts and gravel boards appeals to me initially.

Reply to
rtreter
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Shouldn't they be able to stand on their own feet, as it were, or do they not have foundations?

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for concrete gravel boards;;; You'd be better trying it with kerb stones; concrete gravel boards tend to first bulge (and they break easily) and eventually sort of have that ruptured look, with their rusting internal mesh for all to see.

Reply to
aquachimp

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If you go deep enough with the concrete posts (30" or more below ground level) and have the first gravel board just partly below ground level you should be OK. The spacing of the posts will allow the tree roots to find their own path through. Try to get a good spread of concrete along the line of the wall at the base of each post-hole to provide some resistance to the pressure of the earth at the top of the wall.

Cic.

Reply to
Cicero

This shot doesn't quite show the full nature of the upheaval, but here is one panel that is giving up the fight. The pavement has recently been resurfaced, but is already beginning to bulge again.

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Reply to
Chris J Dixon

Even a kerb stone would be undone in that situation I think. What I thought the OP referred to was gravel boards all the way up.

Reply to
aquachimp

I have seen a retaining wall made from concrete fence panels three high. It broke in several places within a couple of months. The last time I saw it they had inserted extra concrete posts in the centre of each panel, AFAIK they are still holding it back after a few years.

Reply to
dennis

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