Garden retaining wall advice

[GravesendPaul]

Hi all

Long time lurker, first time poster here. Hope someone can help.

I live in an end of terrace house, which is on a slope. Facing the front of the terrace, it slopes downhill to the left and my house is the end on the right, at the top of the hill. At some point in history the owner raised the garden level and built a wall between my and my attached neighbour's gardens. The wall, below with pics from neighbour's garden, is approx 1.2m high and 10.5m long, branching off the end of my conservatory. The earth behind is approx 40cm lower than the top of the wall, so the wall is retaining earth approx 80cm high.

Untitled

• GravesendPaul
• 3 Feb 2013
• 1

Untitled

• GravesendPaul
• 3 Feb 2013
• 1

The neighbour complains it is leaning and looks likely to fall - I'm not necessarily agreeing, but want to do something about it. I'm pretty sure I own it since it is aligned with my conservatory wall, and I assume there was no wall before, just a boundary line. I assume it wouldn't have been built over both properties when initially built.

Anyway, a builder has suggested the wall be replaced by concrete posts and slabs, then backfilled with some shingle to help the drainage. It seems there is no drainage in the current wall. My question is really around whether concrete slabs would be strong enough to hold back 0.8m of earth, and is there anything else I need to consider in the job. Not sure yet whether to have a go myself, or employ someone. The builder quoted around £2k for everything.

Any thoughts?

Second part of the questions. Builder seems to think the wall is far from fit for purpose as it is, and obviously so. Is a wall like this something that should be picked up on a HomeBuyer Survey? I know its not a detailed report, but there is no mention at all of a retaining wall, when the report does mention other, lesser, things. It seems they didn't even know the garden was raised. It would have been easy to access the garden next door to take a quick look at the wall... Anyone have experience of complaints procedure etc?

Many thanks

Pav

 

[peterperfection]

It's only a matter of time before the wall 'gives out'. Could be next week , could be next year or 2 .
It's the collection of water on YOUR side that is making the wall 'Bow'.

There are a few solutions . Cheap to do solutions and more expensive solutions.
One solution however that has been mentioned to you- is the concrete post and panels jobby. I would not at all consider that. Far too much loading for mere concrete posts and panels .

Most simple solution is to dig down your side of the wall and remove the earth and (as been mentioned) fill with gravel /limestone. Then drill some holes from your neighbours side and insert rainwater pipe inserts.
Problem with this though-- is your neighbour would have to agree to maybe have a few constant cascades of water into his garden when 'as we do'-- get lots of rain here in UK.
Also- a few simple brick butresses on your neighbours side (more expense) would help enormously to keep the wall from collapsing .

Very best solution though is to remove the earth on your side-- knock the wall down and have a new wall built and lower the ground level on your side-(900mm wide next to wall)- maybe to 400mm depth less than current depth and form a pathway .
Also fit a drainage sort of system under the path--again running into your neighbours land .
May sound drastic-- but in reality--it's just lots of donkey work and not too much materials .

 

[GravesendPaul]

Thanks. So what kind of cost do you think would be involved with having a new wall built etc? Cost is quite a constraint. And you're suggesting a path along the wall at 400mm lower than current depth. Would I then need a new retaining wall, albeit only 400mm, between the path and the lawn? I suppose if I did this then the replacement wall would only need to be a little over 400mm or so to hold the path?

Unfortunately I also have a shed at the back alongside the wall which is on concrete...

Don't think I would get problems with keeping the wall and inserting drainage, but you think the wall would still stay up? Not sure if they'll be up for buttresses...

In terms of the panels, should they ever be used for retaining earth and if so, just small heights? I do have them on the other side of my garden holding back about three feet of earth, but that earth only goes back about three feet before another wall (I'm surrounded on two sides by ten'ish foot high walls with higher gardens).

 

[peterperfection]

Thanks. So what kind of cost do you think would be involved with having a new wall built etc? Cost is quite a constraint. And you're suggesting a path along the wall at 400mm lower than current depth. Would I then need a new retaining wall, albeit only 400mm, between the path and the lawn? I suppose if I did this then the replacement wall would only need to be a little over 400mm or so to hold the path?

Unfortunately I also have a shed at the back alongside the wall which is on concrete...

Don't think I would get problems with keeping the wall and inserting drainage, but you think the wall would still stay up? Not sure if they'll be up for buttresses...

In terms of the panels, should they ever be used for retaining earth and if so, just small heights? I do have them on the other side of my garden holding back about three feet of earth, but that earth only goes back about three feet before another wall (I'm surrounded on two sides by ten'ish foot high walls with higher gardens).

Cant comment on the cost of a wall down your area. Your local builders have different prices than we do up North .
They do not however have to sting you on cost of bricks. Many suppliers have 'slight defect' bricks that are maybe 80% lower than the 'perfects' price-at the builders merchants.
The wall can also be 'intermingled with cheapo blocks too--especially under ground level.
yes you will need a small retaining wall on your 'Lawn' side of the path-- Purely 80% cosmetic though . Just to stop your path getting mucky.(the water/loading- will be further down.

Yes-- quite correct-- the NEW retaining wall could be lower --say about 600mm BUT- I'd keep it at the level it's at now -complete with higher level drain holes .

Just take a step back and 'think'-- consider it as if you are in a 'waterfall'
Neighbours higher up than you- and 'otherside of the problem wall' lower down the chain.

Yes-- I do believe that if you put maybe 1 per Metre drainage holes in the current wall-- It MAY keep things at bay. But - a couple of buttresses on neighbours side (properly constructed) would assure the walls survival.

Actually- buttresses look quite nice 'to a Brickie'. It is a old skill indeed.
Regarding your neighbours maybe not liking a buttress- I'd say build a BBQ on the back of them-- for them.


ps-- it's about time your neighbours shifted some of their binbags and bought themselves a Lawn Mower huh ?.

 

[dann09]

1. When did you buy the house?

2. Is that when a surveyor did a Homebuyer Survey?

3. DId the surveyor mention the Wall-Tie Patress Plates in-situ ( upper left on pic 2 ) on a sloping site, end terrace with a knock-thro below? I know that it's not your main concern, but you did introduce a survey into the questions.

4. You must determine the legal boundary - from the pic you appear to be over the line ie. beyond the middle of the party wall.

5. Can you do more pics of your side and your elevation to roof.

6. The wall has failed, the render is delaminating at the oversailing block courses - indicating sideways pressure.

7. Where is your soil pipe ( S&VP )?

8. The manhole/IC is positioned for a shared lateral sewer.
BCO would likely condemn it for no common/legal access, and lacking working height.
The lintel appears to be of wood?

 

[^woody^]

I can't see what the problem is. The wall has failed for whatever reason. Posts and boards wont be good enough.

A new 215mm wall in blocks or bricks will cope no problem with this amount of retained earth. The foundations may need to be checked and replaced too if inadequate

Drainage has nothing to do with it and wont be a solution now

The rear garden would get a brief looking at on a Homebuyer survey, but the surveyor would not go next door to look at the wall from that side. It depends how obvious it was from the property's rear garden

 

[GravesendPaul]

1. When did you buy the house?

2. Is that when a surveyor did a Homebuyer Survey?

3. DId the surveyor mention the Wall-Tie Patress Plates in-situ ( upper left on pic 2 ) on a sloping site, end terrace with a knock-thro below? I know that it's not your main concern, but you did introduce a survey into the questions.

4. You must determine the legal boundary - from the pic you appear to be over the line ie. beyond the middle of the party wall.

5. Can you do more pics of your side and your elevation to roof.

6. The wall has failed, the render is delaminating at the oversailing block courses - indicating sideways pressure.

7. Where is your soil pipe ( S&VP )?

8. The manhole/IC is positioned for a shared lateral sewer.
BCO would likely condemn it for no common/legal access, and lacking working height.
The lintel appears to be of wood?

Hi Dann

Purchased in early 2008 with survey done at the same time. The survey mentions sloping site, and separately mentions tie bars in gable flank and rear walls (I have two sets of ties on the flank that are about a third of the height of the house). It's on a front to back slope too - from the road it's two stories, from the rear - three.What do you mean by knock-thro below?

Can do some pics later possibly. My soil pipe comes from the toilet at the front of house (lower ground, outer wall side) follows the flank wall, turns under conservatory and exits into that manhole. House is C1900 and the drains up to the manhole are covered by ex-section 24. Yes lintel is wood.

Woody - actually just noticed the following: "substantial retaining walls have been constructed at the rear and these appeared satisfactory." I would assume they are talking about the two other high walls retaining other people's land. Would they not take a look at all walls if access was obvious?

 

[freddiemercurystwin]

Homebuyers surveys are not worth the paper they're written on, that is a highway to nowhere.

 

[dann09]

1. The OP never came back with the promised pics, however:

2. My ref. to drainage obviously had to do with the manhole access and usage, nothing was claimed, or implied, for drainage influencing the faiure of the retaining wall.