Retaining wall Wood or Stone?

[tacofleur]

I have no previous experience with retaining walls whatsoever, and hope to find some answers to my questions here.

My main question is, what is the best material to go for, wood or stone?

The wall is about 3 to 4 meters high, and I like to split the wall into 3 or 4 levels, with each level being able to plant plants, i.e. dirt in between the levels.

What is the cheapest to go for?

Thanks in advance.

[soundman]

Any timber retaining wall will eventually rot, no iff's or butt's. Looking round town here at the moment I'm seeing a number of failed timber retaining walls that would be between 10 & 15 years old.
By the same token I'm also seing some brick ones failing for different reasons. Basicaly bad design.

As don bourke says If you can't step over it you should be getting professional help, at least in the design.

pay attention to structure, drainage, batter & soil type.

[bitingmidge]

1) Don't do cheap.

2) Don't do wood unless you want to do it again some time in the next five to ten years.

3) Find an engineer and get a design properly drawn.

4) If by stone you mean a nice random stone wall with lovely pointing, get a concrete or reinforced block wall behind it to stick it on, if you mean you want to stack great big boulders on top of each other, fine, but in both cases see 3) above.

Finally, make sure that the wall is properly drained and back filled so that it is there for all time.

The consequences of building a cheap retaining wall can be very expensive indeed!

Sorry to be so stern, but there is no easy way for this one!
Cheers,

P

[tacofleur]

I definately want to hire a professional to get the job done, any links to websites you can provide?

Can you eleborate on

"make sure that the wall is properly drained and back filled"

Sorry but I'm really new to this, I appreciate your effort.

Any ideas on the price? Just like a very very ruff figure? I have requested some quotes but if you can give me an idea?

There is only the back wall (3-4 meters high) approx. 20 meters long.

Thanks again..

[Gumby]

I've recently put one up which is the Nubrik Linkwall system. The blocks i used sre called Vertica....they are about 50kg each !

Look at this site.

http://www.nubrik.com.au/downloads/8_easy_steps_to_link_wall.pdf

Back fill with rock/stone and the water runs through if it gets overloaded. They look good but aren't cheap. At least you can do it yourself.

[Robert WA]

There are a number of concrete products for retaining walls.

I built one from "mini-crib" some 15 years ago, about 1200 mm high at its highest point, and it is still standing.

I have seen it used here in WA by our Main Roads Department for walls 3 to 4 metres high in cuttings and the like.

That product has the advantage of a partially open face so that you can grow plants in it. You don't need to step it back as in terracing because it slopes into the retained earth.

Concrete doesn't last forever, but it outlives timber by a long way.

[tacofleur]

They look good, and probably more sturdy than a wall made out of loose boulders.

Their website is not much help for prices and installation etc. Any idea on the prices and where to go to get it installed? Or at least get help or professional guidance on the installation?

[Robert WA]

Hmmmmmmmm?

Mini-crib seems to have changed its name.

The stuff I am talking about is the left hand picture on the site below.

http://users.chariot.net.au/~rwi/

[tacofleur]

I did a search for mini-crib in google but no results, any links to websites to read up about this material? I'm open to everything at the moment.

cheers.

[Gumby]

Originally posted by tacofleur
They look good, and probably more sturdy than a wall made out of loose boulders.

Their website is not much help for prices and installation etc. Any idea on the prices and where to go to get it installed? Or at least get help or professional guidance on the installation?

Soory mate but can't help with the exact price. I got mine through the builder who was originally going to do a sleeper wall and that was included in his quote with other building he was doing. I just paid him the extra when we decided to go for the link wall. A call to Nubrik tomorrow will sort it out. They had people here in melb who they could put you on to and they'll do a full install. Not sure about interstate.

[theborg1]

Hi Tacofleur,

I recently had a retaining wall built. Depending where you are located, if in Victoria you are required to obtain a permit and engineering computations/drawings where the retaining wall is in excess of 1mtr high.

I used the AB Blockwall supplied by C&M Brick. The relevant site is as follows:

http://www.cmbrick.com.au/retain_install_allanblock.html

If you use this system, make sure you use a contractor recommended by C&M brick. I didn't and had a lot of difficulties with him not doing what he said he would do.

If you call C&M, they will tell you the cost of the blocks, I believe they also have access to engineers who will produce the plans.

The blocks/materials cost me approx. $3,000 and the labour was $3,500. The length of my walls were just under 1 metre by 10 mtrs (included a stair well of 1.2mtrs wide), and a wall 11.5 metres in length which stepped down from just under 1 mtre to 30cm.

I cannot recommend the contractors I used, just the opposite.

Good luck and hope the above helps.

Theborg

[bitingmidge]

Mr Cautious back for another speech!!;)

Council's allow construction of retaining walls less than a metre in height without engineering details for a reason: if they fail there is little likelihood of serious repercussion. Above that and things get more complicated.

3-4 metres high is a serious retaining wall, and will put serious surcharge loads on the ground on which it sits, even if you build it in three or four one metre high steps, unless you mean steps two or three metres apart, and you are therefore building a series of one metre high walls which don't impose loads on each other.

You will need to have a substantial footing, designed in reinforced concrete even if you go the interlocked block route.

There are a number of concrete block systems ranging from garden walling to the sort of crib walls you see beside freeways which are capable of being built to quite significant heights, but it is foolhardy to guess at what your wall might cost without knowing anything of the soil conditions.

At the one extreme, you could have a solid rock excavation which would need no support at all, on the other a highly reactive soil on a slip plane which could require a piled footing system.

At the height you are talking, drainage means more than rock and gravel I'm afraid. You'll need a geofabric filter to stop the "fines" in the soil settling into the gravel and rendering it useless, you will probably need slotted pipes at a few different levels as well.

At 4 metres or even 3, the consequences of failure could be severe, but at the least you'll get to build it again!

Don't speculate.

Don't try to obtain an engineering degree over the web in a weekend.

Look in the yellow pages under "structural engineers" to find a local firm that can do the job. Ask at your local council office for a recommendation.

A competant engineer should be able to give you an indicative estimate for the work as well, but don't expect advice for free! (Pay peanuts and you can expect to get a monkey.)

I am not an engineer, and have spent a lot of time arguing with members of that profession because they are such a conservative bunch of so and so's, but every now and then (like now) they are a necessary evil!!

The increasingly boringly concerned that you'll get hurt (physically,financially or both),

P

[Robert WA]

Anyone can build something that will stand up. It takes an engineer to build something that will just stand up.

Having said that, the advice that you get engineering advice is good advice. There are too many variable factors for you to just have a go, or let the local builder or landscape gardener have a go.

I would start by going to your local government engineering section. If not able to give you specific advice, they can point you in the right direction.

Any supplier of a restraining wall system should give you information as to load bearing capacity, height limits and foundation specifications. If you come across a supplier who won't do that, find another supplier.

[soundman]

a couple of years ago a 3 metre or so block retaining wall colapsed in a car yard in brisbane after very heavy rain, made a real mess of a whole row of new cars, fortunately no one injured.

From what I heard this wall was destined to fall down from the day it was built, it was just a matter of time.

this was a plain straight block wall filled from behind. No batter no butressing, scant reinforcement, drainage??? a few weep holes.

there are a lot of retaining walls in a similar situation.

I wouldn't lean against one to have my smoko.