Help with Retaining Wall

[Blazeit]

Hey guys, i am embarking on a garden makeover and have a few questions regarding a retaining wall which i would like to build.

Fist some info the wall will be 900mm high and will be "L" shaped the longest side will be 3200mm long and the shortest 2000mm long. I am looking to use besser blocks with mortar. The wall will be used as a raised flower bed decorative.

Now for some questions:

1. How deep do i need to dig the footing?

2. Will i need to use reo bars in the footing and up through the blocks?

3. what would be the best option for drainage, leave weep holes in the base course with ag pipe and blue metal in behind the wall?

Any other suggestions that may help me in making this wall sturdy and lasting would be much appreciated.

cheers,

Ben.

[autogenous]

Its hard to say about the footing at that height. Often footings to suit those types of walls are heal and toe footings with at least some y12s to go up the centre of the core at least every 4th core.
Engineers detail is always good.

1. How deep do i need to dig the footing?

This will depend on the type of footing

3. what would be the best option for drainage, leave weep holes in the base course with ag pipe and blue metal in behind the wall?

if you are in clay type soils, yes. clay or similar have poor drainage

Go for a 6 sand : 1.5 cement: .5 lime mortar mix a little bit stiffer than brick mud so it is just workable to wipe on or slide spread.

If the blocks are "wet" dont lay them.

Can't find Borals Spec sheet for footing design. They have their home handyman product Connex which requires no joint mortar.

http://www.boral.com.au/CB/products/...asonryProducts

[journeyman Mick]

........
1. How deep do i need to dig the footing?
.............

Depends on the soil type and footing design.

........
2. Will i need to use reo bars in the footing and up through the blocks?...............

Yes, size and spacing as specified by engineer.

........
3. what would be the best option for drainage, leave weep holes in the base course with ag pipe and blue metal in behind the wall?
...............

Ag pipe (with suitable fall) and blue metal (trench rock) behind the wall, covered with geo textile to stop fines clogging it all up. If possible I prefer to run the ag pipe out to a low point and drain all the water through it, rather than having unsightly weep holes.

........Any other suggestions that may help me in making this wall sturdy and lasting would be much appreciated...............

Horizontal reinforcement every second course of blocks and possibly two bars in the top course. Every core filled. Back of the wall coated with a cement/silasec mixture (2 coats) and 2 coats of bituminous paint.

Mick

[Blazeit]

hey guys thanks for the input, the ground is a clay makeup and the footing will be poured concrete.

[journeyman Mick]

Footing design encompasses more than just deciding they will be of concrete, I'm afraid and there's more to soil type than just "clay". You really need to get an engineer to design the footings as they may need to be "L" shaped. Size, depth and quantities of reinforcement are all variables.

Mick

[Jacksin]

Have you considered Boral Gardenwall blocks as an alternative?

No footing to pour, can be built up to 1m high, various colours and look heaps better than Besser blocks.

[Camart]

Hi Ben

I built a besser block retaining wall about 6 months ago which was about 800mm high (4 blocks high using 200 series blocks) and roughly 18 metres in length with a zip zap shape. I was not sure what I was doing but here is what I did, hopefully it mite help you a bit!

For the footings I made my own footing cage using "ligs" (I think that is the technical term 200mm by 200mm joined by y12 steel rods. ( I would not make these up myself again. You can get pre made footing cages for a little bit extra, but lessoned learned!). I also had the starter bars which I had going in every second block hole.

I laid the first 3 layers of blocks then added a horizontal steel bar and then laid the top block over this. I used a channel block for this hoziontal bar to be inserted in.

I then core filled the holes with the starter bars, then waterproofed the back of the wall and added gravel and ag pipe behind it.

Maybe this was overkill but I was not sure what i was doing but it has been 6 months and so far so good.

I found this document from hanson quite a good reference. I did not follow it precisely but gave me some ideas.

http://www.hansonbp.biz/document_get.aspx?id=195

Hope this helps
Cameron

[autogenous]

Have you considered Boral Gardenwall blocks as an alternative?

What make you house look like a freeway off ramp and depreciate it $50000

They definitely have their place. They do look alright. However I have never seen them used in around a flash house.

Blazeit hasn't said what soil type he has yet?

There is also concrete post and panel retainers as well which serve a purpose and look half decent.

http://www.twinside.com.au/walls_fences_perth.htm

All good for DYI people.

[Blazeit]

Hey Cameron thanks for the run down what depth did you dig your footing to and was the footing L shaped or just cubed. ie.
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Also autogenous i'm not 100% sure of the soil type in technical terms all i know is it is of a clay makeup.


cheers,

Ben.

[autogenous]

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| side view |
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That would be a section detail of the wall...

Clay make up is generally a little up sized due to the movement in the soil through water take up and evaporation.
You should put drainage in at the back of the retainer as well being clay.
An engineers section detail may save you money rather than guessing.
he may make it very simple.
I wouldn't say the detail will cost you a lot of money. Its worth calling and asking how much.

[sports fan]

in nsw retaining walls over 300mm in height have to be designed & certified by an engineer.... but if you follow that heel and toe design someone described earlier should have no problems.. make sure you include weep holes, ag line behind wall has fall etc

[Camart]

[quote=Blazeit;696020]Hey Cameron thanks for the run down what depth did you dig your footing to and was the footing L shaped or just cubed. ie.
|-------------------------------------------|
| side view |
|-------------------------------------------|


Hi Ben

The footing I dug was "cubed" and around 25-30cm deep. I think it was around 30-35cm wide. In it I had the 20cm by 20cm footing cage.


Cheers
Cameron

[Jacksin]

Surely Autogenus you cant be serious?

There is also concrete post and panel retainers as well which serve a purpose and look half decent.

http://www.twinside.com.au/walls_fences_perth.htm

We use that cheap looking rubbish to line expressways as a noise barrier and somewhere for the graffiti vandals to amuse themselves. They are constantly repairing them as vandals practice their kicking and break the panels in two.