# Forum Home Renovation Retaining Walls  Plz advice a cheap but permenent retaining wall solution

## gamesover

Hi, my whole backyard is located on a slopy land. There is a broken wall laid by previous owner. No concrete, no footing. I have no choice but to pull down and build a new one. 
Surely, it is a true retaining wall, NOT for decorative. I have no requirement of cosmetic; whereas it must be strong, permanent and comparative cheaper-I understand there is actual no cheap solution. 
The current soil is around 1.2m in height X 19m in length. But a lot of builders said the machine(digger or bobcat) is not easy to access. However, they can manage it. 
A) It is said a rock retaining wall is the cheapest. A builder quoted me a moss rock retaining wall $7000 to build a 1.4M in height x 19M in length wall. He said for moss rock one, there is no needed for footing, drainage and council approval. My friend told me footing is no required for moss rock, but drainage(ag pipe) is stilled needed. My council told me any retaining wall higher than 1M needs their approval, even a moss rock one. I am confused, who is right? 
B) Another builder quoted me $8000 to build a 1.2M concrete sleeper retaining wall. In addition, he suggest me do not let council knows and they will put some soil at the base of the retaining wall to make it looks like 1M only. Some builder also suggest me to build 1M concrete sleeper only. However, my current soil is 1.2M in height. Would a retaining wall 1M in height is good to go? 
C) I also received some quotations to build a block or brick wall. At least costs 15,000, some even over 25,000. Therefore, basically I ruled out those block and brick proposals. I really cannot afford to them-certainly, they are much more beautiful than moss rock or concrete sleeper ones. 
BTW, I would appreciated if you can recommand some builders or design companies(in case the wall have to higher than 1M) in Adelaide.

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## Random Username

Strangely enough, the council is right - retaining walls over one meter in height need the certification of an engineer (or engineered plans) and the council's blessing. 
Workarounds include raising the bottom level slightly so the wall is under that height, or using two half meter retaining walls, step fashion - one set back from the other. 
Unless you can find your rock for free, and assuming you aren't a dab hand at drystone walling, you'll probably find that CCA treated timber sleepers will be your cheapest option.  A friend at work is currently having a rock retaining wall built - at about 1.2 meters - and it's costing him $200 per lineal meter for rocks and laying, and that's a developer's 'we're doing a lot of them in the area' rate.  Treated pine works out at about $70-90ish assuming you are doing the work.

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## gamesover

> Strangely enough, the council is right - retaining walls over one meter in height need the certification of an engineer (or engineered plans) and the council's blessing.

  Thanks, I will discuss with rock builder who said council approval is unnecessary.    

> Unless you can find your rock for free, and assuming you aren't a dab hand at drystone walling, you'll probably find that CCA treated timber sleepers will be your cheapest option.  A friend at work is currently having a rock retaining wall built - at about 1.2 meters - and it's costing him $200 per lineal meter for rocks and laying, and that's a developer's 'we're doing a lot of them in the area' rate.  Treated pine works out at about $70-90ish assuming you are doing the work.

   Thanks for your advice. From what I serached in this forum, timber is just a temp solution. You have to replace or repair a timber wall in 5 or 10 years. I seek for a permanent solution. Therefore, timber is not my option.
If 1.2M x 1M =$200, it is a good price, around $167 per square meter. My friend told me a regular moss rock wall charges around $160-$180 per M2.

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## Pulse

Just don't use the stairs.... :Eek:

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## shauck

Rocks/boulders would be the most maintenance free option. Look at nature, he/she always uses this method.

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## Random Username

Good H4 treated pine has a service life of 50 years + in ground.  Check the manual in this thread for information specific to your area - http://www.renovateforum.com/f196/ti...76/#post876556

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## stevoh741

> Good H4 treated pine has a service life of 50 years + in ground.  Check the manual in this thread for information specific to your area - http://www.renovateforum.com/f196/ti...76/#post876556

   Ha, not in qld. Last time I used H4 treated pine it lasted 2 years and was rotted through. Bollocks to 50yrs

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## Random Username

Obviously the results of 35 years of observations and testing at sites across Australia are erroneous, then.

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## Farmer Geoff

Might be worth thinking about 2 shorter walls instead of one high one. A high one will need much greater engineering and strength, any failure would be a big drama and there may be a tendency for the area below the wall to drift into 'out of sight, out of mind' neglect - ie you get little use out of that land. There are enough concrete blocks to build at least one short wall on footings with starter bars and cavity fill. Possibly not need council approval, etc, etc if two shorter walls are a good space apart so that possible failure in the uphill one wouldn't impact on the lower one.

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## shauck

Boulders and Rip rock in the landscape 
This guy talks a bit about rock/boulder walls and is professional.

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## ringtail

> Good H4 treated pine has a service life of 50 years + in ground.  Check the manual in this thread for information specific to your area - http://www.renovateforum.com/f196/ti...76/#post876556

   
50 years + ? Unless its in the Simpson Desert absolutely no chance. Everything H4 pine that I've had to demolish and rebuild has been under 10 years old. Some of it 2 - 5 years old and in 1 case 1 year old and that wasn't even in ground, just a garden bed.

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## stevoh741

> Obviously the results of 35 years of observations and testing at sites across Australia are erroneous, then.

   Obviously. I am going from fact on personal experience and I have seen it rotted out in under two yrs on more than one occasion. Besides the original OP wants a permanent wall so all timber is out IMO.  
To the OP: try the cement manufacturers, they used to use the excess from pours to make large retaking wall link blocks. They are quite cheap and lock together but you need a crane to lift them. Worth a look for price comparison though

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## oceanaussi

Interesting thread! I willhave to build a 70 m long, 1 m highretaining wall, so I'm looking for good options as well.

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## shauck

I reckon boulders would be the easiest (sit back and watch them being placed), least maintenance (it's a rock) and longest in service lifespan (they're millions of years old and counting). Wonder how much 70m would cost tho? At least your grandchildren's grandchildren wouldn't have to save up to replace it.

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## oceanaussi

Howdo the bouldersstay in place? Would I need to get them concreted in? Yeah,not looking forwardto that quote... :Shock:

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## shauck

> Howdo the bouldersstay in place? Would I need to get them concreted in? Yeah,not looking forwardto that quote...

  The excavator will shape the landscape to accommodate and use the soil bank to sit the rocks into/on. it will be stepped into the soil bank so will require a fair width at bottom. Meaning, it won't be a vertical wall, it'll have a batter. So long as you get someone who knows what they're doing, it'll be a case of sit back and watch the magic. Maybe orchestrating from you a bit, as to which rockface you prefer but probably best to let them do their thing.

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## Bloss

The Treated Pine debate arises again. I don't deny personal experiences, but my own tells me the main reason it fails is because users do not follow instructions on it use (I know too many tradies, and DIYers, who simply have never read or followed installation & use instructions or data sheets - and not just for TP!) 
If in-ground and exposed to constant water then minimum is H5 not H4. In coastal areas H5 - so all Qld coast & hinterland H5 is specced for any in-ground application. In all cases any and all cuts must be re-treated - and this is regularly not done, or not done as it is supposed to be from my own observations. I have seen TP failure in under 3-5 years too - but not because of the TP itself. 
Again only my own experiences, but I have many treated pine in-ground installations still in excellent condition after more than 40 years in what I think are less than ideal conditions (in ACT, Tassie and Nth Coast NSW). I bush walk and regularly see TP in-ground in very harsh conditions - the major issue is that gal fixings were used and they often rust out, but the timber stays OK. 
But on the OP question - a structured wall from Boral and others would work well here and easily done by a DIYer eg: Retaining Walls & Retaining Wall Blocks - Boral they are reasonably priced and you can DIY to save labour, they are strong and will last a long time, and the instructions are clear (and available!).

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## oceanaussi

I personally don't like to use timber for a retaining wall. It needs much more maintenance and I have had a realbad experience with atimber retaining wall. 
I like the rock retaining walls. I had a guy come in for a concrete one and am just curious of the quote. I found out there's a lot of earthworks involved as well...  :Roll Eyes (Sarcastic):

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## oceanaussi

I finally have received a quote for the retaining wall and amgoing ahead with 60m2 of concrete rockwall installation starting in 3 weeks time.

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## stevoh741

how much $$$ out of interest?

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## oceanaussi

$10,500 for bricks and labour. Not too bad I thought...

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## Uncle Bob

We once made one from broken up concrete paving. Cost, a box of beer for the truck driver (and a saving for dump charges) and a couple of weekends of back breaking work.

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