# Forum Home Renovation Retaining Walls  Design/Engineering of Retaining wall

## Tubby2

I'm in the middle of excavating my front yard with intention of building a retaining wall to even up the front lawn. Its only going to be about 600-700mm high and I will be building out of either blocks or brick and rendering it. I will be putting a concrete footing down and if I go the block way will put in the starter bars and core fill the wall. 
The question I have is if I go the brick way how many "skins" deep will I need to go.
I want to end up with a double skin wall at the top but will I need to start the wall off at 5 or 6 bricks thick at the bottom. 
I will put in a proper ag drain and it will be retaining a soft clay soil. 
I attached a little pic of where I'm putting the wall to give an idea of the type of soil and wall height. 
Cheers

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## TEEJAY

I don't know what I am giving you but there you go - knock yourself out  :Biggrin:   
Of course both walls require drain and gravel behind.  :Smilie:

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## pawnhead

There's a diagram here:  

> Increase wall width by one course every four courses in height http://www.northrop.com.au/useful/te...ning_walls.pdf

  Sounds about right. 
edit: Eight courses seems a bit light on TEEJAY.

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## patty

hey tubby, Have you thought of using the interlocking retaining wall blocks instead of a besser block or brick wall, with the interlocking wall no concrete footing is needed no starter bars no core filling I am only suggesting this as an option I built a retaining wall 2 tiers first wall 900 mm high wall behind it 600mm high with garden bed bout 600 mm  between the two and it was really a piece of cake plenty of hard yakka but the results speak for themselves  I'll dig up the pics and post them might give you some ideas

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## TEEJAY

> hey tubby, Have you thought of using the interlocking retaining wall blocks instead of a besser block or brick wall, with the interlocking wall no concrete footing is needed no starter bars no core filling I am only suggesting this as an option I built a retaining wall 2 tiers first wall 900 mm high wall behind it 600mm high with garden bed bout 600 mm between the two and it was really a piece of cake plenty of hard yakka but the results speak for themselves I'll dig up the pics and post them might give you some ideas

  
Patty this is the sorta stuff I would build - rendered block walls are very prone to cracking unless you put in vertical control joints every 6m and a solid footing - if they crack they look like absolute crap. 
Interlocking blocks absorb movement as they have joints to articulate through out. They look good too.

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## Planned LScape

You still need some sort of footing, your wall will most likely be either 600 or 800mm high as most blocks are 200mm high. I usually lay down a compacted 100mm c/rock base and lay the 1st course on mortar to get it 100&#37; level and strong, as these walls look terrible if there are and bumps and uneven blocks.  
Once your base level is spot on, the following courses are a piece of pie. Just watch to clean off any "dags" which is caused by the moulding process and excess concrete, and best to lay each course with a stringline at the back to get nice clean lines. 
Make sure you use the Landscape Liquid Nails for the cappers too, the normal liquid nails doesnt last long.

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## TEEJAY

> You still need some sort of footing, I usually lay down a compacted 100mm c/rock base and lay the 1st course on mortar to get it 100&#37; level and strong,

  
Where you buy the block from should have an A4 instruction sheet with recommendations for footing and drainage  :Wink:

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## ozwinner

If you do it in brick do 2 skins with a 75mm cavity that is filled later with concrete.
You still need starter bars with a brick retaining wall. 
Heres one I prepared earlier for blocks, but the principle is the same for brick. 
Al  :Smilie:

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## munruben

> hey tubby, Have you thought of using the interlocking retaining wall blocks instead of a besser block or brick wall,

  This is what I used to retain a garden bed when I had a back patio built at my place last year. No footings but actually sat the blocks on the concrete edge of the patio slab.Filled up the holes in the blocks with blue metal and they haven't moved since I installed them.
My wife helped me and was done in a day. I had considered bricks but I'm no brick layer and to much work anyway. This way, for me was easy.

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## PhilMcCrackin

I can strongly recommend you read this document before you begin your project. I have used the design several times with no cracking or movement. Don't forget to waterproof back of wall and footings if you dont want mineral salts showing up o nthe render in 5 years time.  http://hansonbp.biz/document_get.aspx?id=195

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## Tubby2

Just an update, I've booked in a brickie mate to help on this project and have decided to build the wall using a brick footing. Bricks straight onto the dirt, fist 3 course 470mm deep then step it up to the final 3 courses only 230mm deep. I'm not exactly sure on the dimensions here as I going from memory ( Bricks are 230mm x 110mm x 86mm yeah?) anyway I've been advised that this will more than do the job of retaining up to 1m that I need.

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