Garden Wall building to Tier a slope

[Earlm]

My back garden is a fairly big slope. When we moved in it was gravelled and whilst it looked alright it wasn't really usable. I now want to redo it so that there are a 2 main tiers with brick supporting walls.

Here's the garden:

This is a very amateur diagram of what I'm thinking.

I've never done any building work so will have to get someone to do the wall - I dont mind doing the shovelling. How long would it take a builder to build these walls if I do the digging and dig the trenches? What sort of price should I expect?

I assume this really is bread and butter stuff for a builder?

How far below ground level would the foundations need to be?

Am I thinking along the right lines or does anyone have any better ideas for what to do? Any thoughts?

Many thanks,

Miles.

 

[noseall]

do you intend replacing the side and bottom timber fences with masonry walling?

is there a significant difference in ground levels between the property at the bottom of your garden and your own?

 

[Earlm]

I intend to build walls infront of the fences, only as high as my new ground level + a brick height.

The ground level of the garden at the bottom of my garden is pretty much the same, the slope continues down their garden, as you can see by the top of their fence.

 

[noseall]

just be wary of made up ground. the walls will need to be min 225mm thick so dig down to good virgin earth making the footing min 450mm wide. cast the concrete min 225mm thick or mass fill if you wish.

include some weep holes into the wall using say, square gutter down pipe as it's the same size as a metric brick.

the finished height will govern the wall thickness. any retaining wall above 1200mm needs some serious thickness.

 

[Earlm]

Thanks for the help mate.

I've just stuck some better numbers into the diagram, the middle wall will have to support 2.5 ft of soil, and the top and bottom walls 1.25 ft, the sides will be similar.

The soil seems very clean and firm regular top soil - the houses we only built 4 years ago so its been laid / disturbed quite recently.

How deep roughly do trenches need to be?

 

[noseall]

on solid undisturbed ground, a minimum of 700mm below the surface.

 

[Thermo]

or you could do it with sleepers (dont use reclaimed ones) And you could get a landscaper in to do it!

 

[Earlm]

Thanks again.

I thought about sleepers but they wont fit in with the rest of the house, its a 4 year old flat pack house so the 'rustic' look would be out of place.

As for getting someone in, I'm too tight!

 

[noseall]

p.s. don't forget to raise and level that inspection chamber cover, and be sure to slot and lintel over any drains.

 

[bernardgreen]

A slight curve in the wall resists the toppling effect from pressure behind and permits less depth of foundations to be used.

Worked well on the 2 foot high retaining wall set into the soft ground at the side of the stream that was meandering and eroding our garden. We used dense concrete blocks and will face them some time in the future. In a 15 foot long section of wall the deviation from straight is about a foot.

Foundations were about a foot deep .

A set of steps set through the wall provide a solid buttress anker point.

Bernard
Sharnbrook

 

[noseall]

A set of steps set through the wall provide a solid buttress anker point.

Bernard
Sharnbrook

i kno w anchor point.

i dont kno w anker point.

 

[Earlm]

Thanks again for the suggestions. I was thinking about putting some steps in the middle of the walls.

If I want to use ornate (expensive) bricks, can use cheaper ones in the foundations then build the wall that will be seen on top?

To go 700mm underground would have as much underground as above it? Is that right?

 

[noseall]

you can use 7n dense concrete blocks where not visible, i.e backing in the wall, below ground. if your facing brick of choice is non engineering, then you will need to show at least two corses of class b engineering bricks at and above ground level.

dig down to 700mm pour footings say 400mm thick this will leave for courses to ground level. retaining walls benefit from good foundations.