Garden/Driveway Retaining Wall?

[middleman]

Hoping someone on here can help me with this specific problem. Have done a search but can't find anything like this unfortunately.

I have a space beside my house which I refer to as the 'blind side'. Useless space, can't grow anything except weeds with it's aspect but it would be wide enough to use as hard standing to extend the drive from the front. First I need a retaining wall and drainage to adjust the level bringing it up towards the other level across the front of the house.

Before I go on my neighbour is agreeable to any work providing it's done right from his side as he will be looking at it. Written permission is available if required.

House was built on a sloping site with me being significantly higher up than my neighbour.
Currently there is a double brick wall 0.8m high between us (not really retaining but it has lasted these years although not in great nick) as can be seen below.

Blind Side of House



It's 16m long to the rear of my house. The house front to back is 8.5m and the wall is 3.8m from the house.

I would like to keep the small tree in the foreground with a kerb/bed around it and create an area of hard standing across the front (asphalt probably) running all the way up the side of the house for car parking/trailer etc.

Am I right that the wall will have to be designed and built to spec? Likely cost of design.
I can only see 1 rainwater gully at the side of the house, how will a sort out drainage?
Building control notification?

Have more photos taken from different angles including in the neighbours side looking back at the wall.

 

[middleman]

 

[Blagard]

You are not looking at a major issue but you are absolutely right it must be done properly. To that end I would suggest you employ a structural engineer to provide not only a design solution but to sign off the actual work as being satisfactory.

Building control have no obligations to you, so you cannot rely on them to ensure the works are done properly. There are a wide variety of wall solutions and it will to some extent depend on what you want the finished product to look like as much as the function i.e. hardstanding areas rather than soft landscaping. Having only one gully is probably not really a problem as additional drainage can usually be added if and when necessary. The levels ot the existing drains could be an issue and some excavation may be a good idea to establish the inverts of what is there now.

 

[middleman]

I was informed that I would require a structural engineer to design the wall due to the height and the amount it is retaining. I was also told that it may prove more economical the way as it would be built to spec rather than extra materials being used to overbuild it as such if the builder was doing it without specs and was over cautious (not to blame him obviously).

Roughly what would the structural engineer charge for design? I don't see too many advertised that favour domestic jobs like this one.

With regards to drainage I have manhole covers at the front of my property at the top end of the drive so I'm assuming there must be a pipe in there somewhere for gravity to do it's work.

Do building control have to be consulted about this type of work in a garden? I assume they do due to the nature of the wall.

 

[Blagard]

Any change to the drainage is usually a building control issue anyway. Although you have manholes they may not be to the drainage you need. Generally there are two types of drainage in use, foul and storm. Surface water drains go into the storm system.

Charges by SE's will vary enormosly and ideally you want some-one local. Best to do some ringing around for a quote /estimate and go from there. If you have a builder in mind ask them who they know.

Have a read of the following
https://www.planningportal.co.uk/info/200130/common_projects/20/fences_gates_and_garden_walls/2

https://www.gov.uk/government/publi...d-maintenance-of-boundary-and-retaining-walls

It is also possible you may need to apply for planning permission! Specifically I suspect the wall will increase in height by a fair bit in places. Hopefully some-one with knowledge of such change may be able to advise.
Do not under estimate what is involved and be aware of the party wall act https://www.gov.uk/party-walls-building-works

Specifically Building control does not apply to Garden walls. But you would be best to get professional advice from a SE along that boundary as the height judging from your DPC level could increase significantly.

 

[middleman]

I'm in Northern Ireland where the legislation differs greatly. From what I can see I don't need planning permission for erecting a wall as long as the height does not exceed 2 metres https://www.housingadviceni.org/boundary-disputes.

I will be consulting a few builders and will be making the points to them. I'm not looking to go up as high as the DPC level shown (I'm assuming the DPC is about 2 courses below the coloured brick) as this would indeed be a substantial increase and would from what I can see mean that although my site would then be level right across, the wall would be as tall as the first level of my neighbours house up to the soffits. I can't imagine he would be happy about a wall that size and it wouldn't look right anyway. I may add a small fence to the wall but that would be about all I would consider.

I may also contact my local council authority to seek there advice with regards the planning/building control in any case. Safety of the wall is my biggest concern and obviously managing the run off of any water from my property. As I said most of the SE's I see here advertised seem to concentrate on commercial jobs but they may be able to point me in the right direction if they are not interested in my particular job. I supposed it may be good experience for a recently qualified SE within a larger firm.

You've encouraged me to look into it further though because your about the first person who has said that I'm not looking at a major issue. It was mostly landscapers though who said they wouldn't tackle it as I did need a builder. Landscaping will be for after the wall is in.

 

[Blagard]

I think you have the gist of it. The safety of your neighbour is the most important aspect of what you propose as a collapse of the wall for whatever reason and injury to person or even damage to their car are what you are safeguarding against. Personally I would be inclined to build a 215 dense concrete block retaining wall your side with a cavity then a tied in brick skin in front (on the line of that existing face) for appearance and reduced to brick on your side where it becomes exposed. The foundation needs to be wide enough for all that and possibly a toe to the foundation. Having seen such walls built on sites I have worked, the back can be thickened by further blockwork the taller the wall needs to be and then stepped back as it rises. The cavity with weep holes at the bottom ensures the facing bricks are not subject to ground water and so remain dry and looking good.

 

[^woody^]

That wall looks ok to deal with that small bit of ground.

Don't overthink things. The land bring retained is a 45° slice from 1/3 up the wall and a one brick thick wall is fine for that purpose.

 

[Blagard]

As an example of a pure block retaining wall without a skin of facings I managed to locate one of the first sites I worked on about 40 years ago! The top of the wall is thereabouts at road level topped by handrails. You can see the top 5 courses are a single thickness of 215mm thick blocks (I know because I was there!) then the next courses down from there are blocks laid as headers and futher down the wall gets even thicker. As the steps are in the back of the wall you just see the single vertical face. That was the engineers design there. If also shows the mess of water coming through over that period of time. The ground there was a hillside of shale just on the outskirts of plymouth. Horrible stuff to excavate though as one side of a trench would be vertical and the other side at 45 degees where the layers of shale slide into the trench.

OK bigger than what the OP needs but the principle is good as that one is still there.

Block Retaining Wall

• Blagard
• 12 Oct 2017

 

[middleman]

That wall looks ok to deal with that small bit of ground.

Don't overthink things. The land bring retained is a 45° slice from 1/3 up the wall and a one brick thick wall is fine for that purpose.

Its not really just the small amount of ground but the fact that I'm going to be raising it and turning it into hard standing with drainage to park a vehicle on so the wall needs to be able to support that and to last.

 

[^woody^]

It's still a small amount of ground, and a small load. Raising it makes little difference to the load it retains as the loading is still further down the wall.

 

[middleman]

It's still a small amount of ground, and a small load. Raising it makes little difference to the load it retains as the loading is still further down the wall.

Does the type of soil and amount of water it holds etc not have a bearing on this although I will be raising it with cleaned stone as I have a supply handy? Haven't had any builders look at it yet but I will be wanting them to stand over it with something in writing as I'm not being held responsible if it falls and does damage or worse injures someone. Had a bad experience in the past with a 'retaining wall' hence my reluctance to just throw a wall up.

 

[^woody^]

Does the type of soil and amount of water it holds etc not have a bearing on this although I will be raising it with cleaned stone as I have a supply handy? Haven't had any builders look at it yet but I will be wanting them to stand over it with something in writing as I'm not being held responsible if it falls and does damage or worse injures someone. Had a bad experience in the past with a 'retaining wall' hence my reluctance to just throw a wall up.

Not in your case. It will be no different to what is going on now. Plus, if you are forming a hard standing, then it will be draining somewhere else and if necessary you should be putting in drainage to deal with surface water run off in any case.

 

[r896neo]

First thing to do is to dig down beside the wall, often these walls look like they are just 9'' brickwork from the top but are actually backed up by blockwork and so at their base they can be 13 or even 18'' for a course or two and step in towards the top.

 

[middleman]

First thing to do is to dig down beside the wall, often these walls look like they are just 9'' brickwork from the top but are actually backed up by blockwork and so at their base they can be 13 or even 18'' for a course or two and step in towards the top.

I know this one isn't as the level it is at now was from soil removed from when a concrete base was put in around the rear of the house for a shed 3 or 4 years ago.