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Retaining walls


EverHopefull

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I guess this is a bit like the "How long is a piece of string" question but would anyone know the approx cost for a retaining wall that is 24m long and 2m high (highest point)?

This element of the build is not being quoted by the timber frame guys for obvious reasons but none the less nothing build wise can commence until the wall is constructed.

 

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The answer to your question is highly context-dependent. I suggest you take well-qualified , competent local advice. And network hard in relation to who is going to do the job.

 

Using SPONS Architects' and Builders' Price Book (2016) CRC Press,  - which mentions the construction of retaining walls in the context of building an affordable apartment block: 

  • Concrete retaining wall; temporary propping £510 per m² (Hourly wage rate £260)
  • Excavation and disposal, including dewatering £5,250 m²  (Hourly wage rate £56)
  • Tie in slab edge to retaining wall    £170m (Hourly wage rate £180)

(Page 140)

 

These figures are based on the 2016 rates and, as written,  take no account of geology or other local factors - such as lack of access for example. In that respect, I would expect the first question to be - can we get a machine in to do the job - followed by a 16 tonner or  5 tonner - and what about access for the wagons / dumpers and other  paraphernalia? 

 

Thus for us locally, the figure of £5250 / square meter looks very 'steep ' : Easy access, easy ground, good local contacts,  16 tonner (digger)  and a farmer who needed the  spoil and a plentiful supply of  20 tonners.  Locally, that is not the case now. There is a major shortage of drivers.

Good luck

Ian

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Just been through the detailed costs for our retaining wall, which is around 40m long overall and 2.5m high at the highest point, ~76m² total wall area. 

 

The construction was a large reinforced concrete foundation (2m wide at it's widest) with a double width 215mm hollow block wall keyed to the foundation by being built with steel reinforcement coming up through the block, along with steel reinforcement running through the block bonds.  The hollow blocks were backfilled with concrete so there are vertical reinforced concrete piers within the wall.

 

The basic cost for the wall foundations and structure came to just under £20k, including the SE fees.  On top of that there was an additional £3k to build a stone wall on top of it as a boundary and about £2.2k for the rendered finish to the retaining wall, so overall the cost came to around £25k.  In terms of cost per m² of wall, that works out as being around £330/m². 

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Thanks for all the replies. It is proving to be an ever growing list of "unknowns" for the build.

Current panic thinking is that this build is something that we should not have even begun to think about.

Sadly, I do think that we may just cut our losses and put it back on the market. We will see...........

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15 minutes ago, EverHopefull said:

Thanks for all the replies. It is proving to be an ever growing list of "unknowns" for the build.

Current panic thinking is that this build is something that we should not have even begun to think about.

Sadly, I do think that we may just cut our losses and put it back on the market. We will see...........

We too went through this stage of thinking. a lot of people do.  In fact we did buy and sell a couple of plots without building.  We decided to stick with this one and build it out as it ticked so many boxes for us.  You will always have 'unknowns' it is the nature of the beast.

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52 minutes ago, EverHopefull said:

(...) It is proving to be an ever growing list of "unknowns" for the build.

Current panic thinking is (...) 

 

Welcome to the Oh Sh!t Club. There's hardly anyone on BH who hasn't lost many nights sleep trying to square the circles in today's kaleidoscope. 

A read of the BH blogs is helpful. Look at JSH's for a good story of how even a very competent person can walk slap bang into a brick wall. (The water supply saga) I bet you almost all of us have had - or are working through - a real humdinger of a problem . 

Turn a few of your unknowns into the opposite. 

Keep networking locally. 

Compromise. 

Be persistent. 

Good luck. 

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I had quotes up to £70k for my wall (4m x 14m)

 

I done it for a fraction of that with concrete Lego. It doesn’t need a crane. Farmer and digger worked out fine. 

 

No need for se either. I wasted time and money on silly over engineered designs. 

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12 minutes ago, K78 said:

I done it for a fraction of that with concrete Lego. It doesn’t need a crane. Farmer and digger worked out fine. 

 

I looked at those but thought they would take up too much space, then looked at the bolt down solution (though i am still at the planning stage)

 

https://www.forterra.co.uk/bison-precast-concrete/retaining-walls/the-standard-range/2-5m-retaining-wall

 

These are about £300 - £350 + VAT a pop, without the installation or associated materials.

 

@EverHopefull don't worry there is usually a solution, but takes a bit of digging to find the right one which is cost effective.

 

Just think about the poor developer & SE that got faced with this challenge!

 

20190212_142515.jpg

Edited by Moonshine
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14 minutes ago, K78 said:

I had quotes up to £70k for my wall (4m x 14m)

 

I done it for a fraction of that with concrete Lego. It doesn’t need a crane. Farmer and digger worked out fine. 

 

No need for se either. I wasted time and money on silly over engineered designs. 

 

 

Out of interest, how did you get your insurance company to agree to accept the risk without any SE sign off?   This was what convinced me to pay £360 to an SE, as although I'd designed a couple of retaining wall configurations that complied with Eurocode 7 my calcs weren't acceptable to the insurer.

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1 hour ago, JSHarris said:

 

 

Out of interest, how did you get your insurance company to agree to accept the risk without any SE sign off?   This was what convinced me to pay £360 to an SE, as although I'd designed a couple of retaining wall configurations that complied with Eurocode 7 my calcs weren't acceptable to the insurer.

 

It was designed by the block supplier. Incline, gravity retaining wall. 

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1 minute ago, K78 said:

 

It was designed by the block supplier. Incline, gravity retaining wall. 

 

Sounds fine, Stepoc offered that in their package when they quoted to supply blocks for our wall (couldn't use them as the neighbour wanted a stone wall on top for the boundary, rather than the timber fence that had been there...).

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1 hour ago, Moonshine said:

 

I looked at those but thought they would take up too much space, then looked at the bolt down solution (though i am still at the planning stage)

 

https://www.forterra.co.uk/bison-precast-concrete/retaining-walls/the-standard-range/2-5m-retaining-wall

 

These are about £300 - £350 + VAT a pop, without the installation or associated materials.

 

@EverHopefull don't worry there is usually a solution, but takes a bit of digging to find the right one which is cost effective.

 

Just think about the poor developer & SE that got faced with this challenge!

 

20190212_142515.jpg

 

I looked at boltdown concrete panels similar to those. I had a quote and was going to use them. Couldn’t find a SE who would do the design. 

 

The concrete company recommended one based in Chester. He wanted £5k for a design. 

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Just now, JSHarris said:

 

Sounds fine, Stepoc offered that in their package when they quoted to supply blocks for our wall (couldn't use them as the neighbour wanted a stone wall on top for the boundary, rather than the timber fence that had been there...).

 

Incline gravity walls are commonly used for river bank reinforcement/erosion protection. I used the incline foundation to reduce the footprint. 

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6 minutes ago, K78 said:

 

Incline gravity walls are commonly used for river bank reinforcement/erosion protection. I used the incline foundation to reduce the footprint. 

 

 

Funnily enough, the reason I didn't use a retaining wall with batter was to reduce the footprint!

 

Building a vertical retaining wall gave us about an extra 1.5m of garden, plus allowed the house to be positioned a bit further back towards the wall, whilst still allowing for a decent path around the back.  In turn, moving the house back allowed the drive to be extended up past the front door, giving us more parking space (proved to be really useful when I got an electric car, as it made positioning the charge point I use most of the time easy).

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3 minutes ago, JSHarris said:

 

 

Funnily enough, the reason I didn't use a retaining wall with batter was to reduce the footprint!

 

Building a vertical retaining wall gave us about an extra 1.5m of garden, plus allowed the house to be positioned a bit further back towards the wall, whilst still allowing for a decent path around the back.  In turn, moving the house back allowed the drive to be extended up past the front door, giving us more parking space (proved to be really useful when I got an electric car, as it made positioning the charge point I use most of the time easy).

 

I was shocked at the width of a non incline gravity retaining wall.

 

I would have preferred sheet piles or soil nailing but not at the quoted prices. Block was a lot more expensive too and still needed a wide foundation. 

 

With sheet piling I would have gained a metre, but it would have been a very expensive 14m2. It wasn’t economically viable for me. 

 

I really thought the retaining wall would blow my budget and I would have to sell. Thank god for concrete Lego. 

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4 minutes ago, Alexphd1 said:

Anybody looked at ICF for a retaining wall, most manufactures produce up to 300mm concrete core and some even more. Certainly possible to DIY & a lot cheaper than any of the figures above.

 May work out cheaper at 2m height?

 

Was more expensive for my wall before I factored in SE cost. 

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18 minutes ago, K78 said:

 

I was shocked at the width of a non incline gravity retaining wall.

 

 

 

Interesting, as our wall is 430mm thick at the base, 215mm thick at the top.  Any of the block systems I looked at were going to be three or four times wider than that, as the key distance for us was from the base of the wall on our side to the face of the wall on the neighbours side.  The thinner we could make that the more room we got.  In the end, because the lower part of the wall is under the neighbours garden, the wall only lost us the top section thickness of 215mm, plus the thickness of the render, so maybe 230mm in total.

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39 minutes ago, Alexphd1 said:

Anybody looked at ICF for a retaining wall, most manufactures produce up to 300mm concrete core and some even more. Certainly possible to DIY & a lot cheaper than any of the figures above.

 

For a 300mm core, ICF will work out about £150m². Ordinary shuttered concrete will work out much cheaper as you can build the formwork yourself.

 

We're building a partial basement and there will be an external retaining wall extending for about 4m out from one of the gables. It's my intention to build everything out of ICF for ease and speed - single pour etc.

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our retaining wall is 9M and around 2.4M high (we will have to remove some soil above to get down to that). Basic SE design, foundation with key, vertical rebar, 2 courses of 100mm blocks and 150mm gap filled with concrete.  Had a quote for £16K and not going with that! The first 1.5M is rock so its only holding 1.5M ish of soil. looking at other options. Nothing above it except sloping (wooded) ground. oh, and access is crap, so anything that takes less concrete is a billy bonus

Edited by redtop
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