Another retaining wall.

[Roger Hayter]

The recent thread about a retaining wall problem prompted me to post this picture of a very recently built retaining wall locally. I would be quite interested in opinions on it. My impression is that building control may not have had very much input:

It is about 3m high and about 6m long. The near bit is in front of an existing retaining wall but the two thirds of the length away from the camera has replaced a retaining wall nearer the road. It is built of roughly rectangular stones about one to three tons in weight and laid dry on top of each other in rough courses, four to five. Below the lowest visible course some similar stones have been buried, but not as single stones for the whole thickness of the wall and there are no formal foundations. The road is an official "C" road. There is a (as in the picture) a house a few metres back from the top of the wall.

I see this as a disaster waiting to happen, but am I being too pessimistic?

PS there is no material in the horizontal beds between the stones, but some very tasteful ferns have been planted in some of the gaps at the corners of the stones.

[Steve Walker]

I have no experience of retaining walls, but looking at it, I'd say it's going to take a fair bit to shift hose big stones.

[williamwright]

I built a similar wall about twenty years ago. Mine was made from stones that could be lifted by a JCB, and smaller ones. The wall was 4 metres high so I had to build an ad hoc scaffold. It was keeping back ground five metres high, the top metre being sloped back at 30 deg to the horizontal. I put in a concrete foundation and used concrete as mortar. I put weep holes along near the bottom, and low down behind the wall left a gap that I filled with rubble to allow the water to find the weep holes. I angled the wall back at about 10 deg to vertical, and used smaller and smaller stones as I worked my way up. I planted the nooks and crannies with flowers, and to encourage moss sprayed the wall with diluted cow shit. This worked well. After I'd built the wall (it took me months) I was immensely strong, but I lost the strength quite quickly. The wall hasn't moved at all.

Bill

[Andy Burns]

I'm building* a house that requires a retaining wall and building control have confirmed they have zero interest in the retaining wall, other than guarding against people falling off it, and even they're "guidelines" rather than hard rules from part K.

Can't see them rocks going anywhere, but depending on what's on the other side, it might not satisfy the fall protection "guidelines".

Mine will be "one ton lego" blocks, they come in various designs that loosely interlock and doesn't need any formal design for walls up to 2m high, you can just buy them and stack them, above that height the supplier designs/approves.

[*] it's been on pause for a year.

[Jimmy Stewart ...]

Builshit ...in Scotland anyway we delt with loads of proposed retaining and failing retaining walls ....stone concrete gabions brick block or timber ......

[Andy Burns]

All sounds good, today they'd probably say just use compacted MOT type 1 instead of a concrete base, put geotextile against the back face, and use perforated drain pipe instead the rubble at the base ...

[Chris Hogg]

Yes

[Roger Hayter]

What if some of the lower stones sink more at the front and the upper ones slide off? Or the soil behind the wall gets very wet and forces out some of the middle blocks?

[Jimmy Stewart ...]

stones used as foundations are called footings rather than foundations what they used to do in the past and it worked well.....

[The Natural Philosopher]

That's what engineering calculations are for...

[Jimmy Stewart ...]

stone...titter titter....

[Jimmy Stewart ...]

totly

[newshound]

Agree with you. Might be OK now, wouldn't like to speak for 50 or 100 years time. Although any dangerous distortion should be visible before it collapses.