# Forum Home Renovation Retaining Walls  Besser Block Retaining Wall Footings Design

## plucka

Hi,
Would like opinions on this footing design:  Wall will be 12M long built with 400x200x200 blocks.  To complicate things the ground slopes by 1M over the length and will also be curved wall.  Because of the slope I will use a stepped base wall in 5 sections thus: 
Section     Size(LxH)     Footing Size(WxD)     Trench Steel     Vert Starter Bars
    1         2.6Mx200       300x200                      None                   None
    2         2.2Mx400       300x200                      None                  every 400
    3         2.6Mx600       300x250                    200x200 Cage       every 400
    4         2.2Mx800       350x300                    200x200 Cage       every 400
    5         2.4Mx1000     350x350                    200x200 Cage       every 400 
Core filled of course.
Concrete Calculations: Footings-1 cubic m, Core Fill: 1/2 cubic m. 
Soil is clay, retaining soil garden bed.  Is trench cage ideal or can just use mesh instead? 
Thanks,

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## METRIX

Best off to speak to an engineer regarding specifications, as any retaining wall over 1m in height requires engineers sign off to ensure it is constructed safely.

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## barney118

> Best off to speak to an engineer regarding specifications, as any retaining wall over 1m in height requires engineers sign off to ensure it is constructed safely.

   :What he said:  
Unfortunately engineer needed here. 
Since you are in gods country try these dood, looks impresive: I havent bother to call them for mine yet, as delivery to NSW 900 klms away might not be cost effective. http://www.renovateforum.com/f215/ne...roduct-107380/

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## shauck

No comments on construction method but the wall isn't over 1m. It's only up to 1m at it's highest point so surely that doesn't require an engineer???

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## plucka

> Best off to speak to an engineer regarding specifications, as any retaining wall over 1m in height requires engineers sign off to ensure it is constructed safely.

  It's not over 1M. 
I found this interesting pdf: http://www.materialsintheraw.com.au/...ing%20Wall.pdf 
Seems a wider but only 200mm deep footing is the go.  Might follow this guide.

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## plucka

> Unfortunately engineer needed here. 
> Since you are in gods country try these dood, looks impresive: I havent bother to call them for mine yet, as delivery to NSW 900 klms away might not be cost effective. http://www.renovateforum.com/f215/ne...roduct-107380/

  Interesting product but that's going to help me with a curved wall is it.

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## METRIX

> It's not over 1M. 
> I found this interesting pdf: http://www.materialsintheraw.com.au/...ing%20Wall.pdf 
> Seems a wider but only 200mm deep footing is the go.  Might follow this guide.

  If it not over 1m then no engineer required, The most important thing with any retaining wall is the get the moisture away from the base of it, and it the number one reason for failure of any retaining wall. 
As a general rule, this is usually done with agg pipe at the base surrounded by fine blue metal and covered with geotext fabric, before putting soil back.
Follow the guide it should keep you on track.

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## plucka

> If it not over 1m then no engineer required, The most important thing with any retaining wall is the get the moisture away from the base of it, and it the number one reason for failure of any retaining wall. 
> As a general rule, this is usually done with agg pipe at the base surrounded by fine blue metal and covered with geotext fabric, before putting soil back.
> Follow the guide it should keep you on track.

  
Yep goes without saying,  will waterproof the inside wall and use socked agpipe, blue metal all wrapped in geofabric.  What do you reckon 65 or 100mm pipe?

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## METRIX

Sounds like you on the right track, I would go for the bigger Aggie, as 12m is a decent length of wall and can build up a lot of water in downpours. 
The price difference is not much, and this way you know it will handle any major downpours with ease, if you have a problem later with the smaller pipe, it is a lot of work to get down to it to up size it, small cost extra now could save you a lot more in the future.

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