# Forum Home Renovation Retaining Walls  I Beam Retaining wall

## oohsam

Hi guys, 
When I bought my house, It came with a 1100meter high retaining wall thats about 3 meters long. It is made from Metal I beams, and the the sleepers are treated pine. 
I have never seen these I beams for sale anywhere nor do I  know how much they cost. Is anyone able to assist on this question.  
Also, Because they are steel, I am thinking that I dont need need to dig as deep holes for them, being steel instead of wood..or am i wrong? 
(The wall will be 1meter high)
Regards

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## pawnhead

> It came with a 1100meter high retaining wall thats about 3 meters long.

  That's a hell of an achievement. You should tell the Guinness book of records, since they reckon the tallest structure is Burj Dubai that just passed the CN tower at about 550 odd metres.  :Wink:  :Biggrin:  :Sneaktongue:

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## Sturdee

Eastern suburbs Sleeper Supplies in Heatherdale Rd Ringwood sells them but I think they are made of aluminium.  
Peter.

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## namtrak

Visit a steel merchant, it is a very common way to build retaining walls. 
From memory (and I think steel has gone up since) the I-beam is around $33 per metre.  And you still need to have a decent hole (600-800) with concrete.

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## oohsam

> That's a hell of an achievement. You should tell the Guinness book of records, since they reckon the tallest structure is Burj Dubai that just passed the CN tower at about 550 odd metres.

  bahahahah sorry bout that. I meant 1.1meters or 1100mm.  
Thanks for the replys guys. 
$33 a meter is so damn expensive...Would be cheaper to build it from just sleepers.

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## namtrak

> bahahahah sorry bout that. I meant 1.1meters or 1100mm.  
> Thanks for the replys guys. 
> $33 a meter is so damn expensive...Would be cheaper to build it from just sleepers.

  You may want to price it all out. 
I think block retaining walls, timber retaining walls and the I-beam walls all work out fairly similar in cost once everything is taken into consideration.

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## woodbe

> Also, Because they are steel, I am thinking that I dont need need to dig as deep holes for them, being steel instead of wood..or am i wrong?

  We built one last year, and I think the below ground depth required depends on the overall height above ground, not the materials used for the uprights. 
Ours used the steel posts and concrete sleepers. It's not that rustic, but very efficient.  :Biggrin:  
woodbe.

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## oohsam

OH i will definatly be pricing it all up....I will visit some steel merchants this weekend to get prices and calculate the cost. 
I am thinking of nailing cement sheeting to it once its finished and rendering it with this paint, it basically looks like bag and paint when its finsihed, without having to cement render it.  
I've seen this done before and it looks great.

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## Planned LScape

I do these walls pretty frequently- I get the steel from a steel stockist, the galvanised UC100 (100 wide) is $37 Lm, but they may charge you for a full length if there is an offcut left, I think a length is 9m long. There will be a cutting fee of around $2-3 per cut, which is very well worth it as it's a bugger doing it afterwards with the 9" grinder. 
I set out my wall 1st, get my heights making sure the depth under the ground is sufficient to the wall height and order them already cut- it saves a lot of time and hassle. Go the galvanised also as the ordinary mild steel ones rust very quickly and look pretty ordinary.

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## oohsam

Thanks for the info PlannedLScape.  
I've done the maths and after costing out everything, the prices are very comparable using steel vs Sleepers as stumps. The upside is that I dont have to bolt/nail each sleeper to the stump with the I/H beam so assembly will be much quicker once the posts are in the ground... 
Just  quick question - 
The retaining wall I will be building will begin at a 1meter height and span for approximatley 10 Meters (2 meters per post), and the wall will reduce in height as the wall continues, it will be about 1/2 a meter at the 5 meter mark.  
My question here is:
1. Should I keep all my depths 600mm still however, order shorter posts 
(ensuring they are high enough to hold the amount of sleepers required for the height) so the wall will stagger down,  
or  
2.Do i reduce the depth of the post holes as well based on the height of the wall at that point? 
or 
3. Do I make the wall the same level all the way (1 meter) but simply backfill the lower points and make a 'garden bed' out of it?  
I know its all personal perferance but some advice would be great....

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## Planned LScape

You could reduce the depth of the posts as the wall gets lower, but it wouldnt be much. 
Generally I put my posts in @ 800mm into the ground for 1m above, for half that I wouldn't go any shallower than 500mm deep. It depends on the backfill of the wall and what sort of material it is retaining- if it is soft clay it will require deeper footings as the clay will be very heavy when wet. 
Last year I had to do a wall on the fill side of a house cut, engineering plans said to put the posts down 1.6m to every 800mm. It put the costs up thats for sure! 
Just get your sleepers to line up with each course of sleepers, it will be nice looking aesthetically then

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## oohsam

Thank you so much for the advice. I really appreciate it.
Im only going 600 deep. The 1100m retaining wall that was put there by the engineers was only 600 deep so Im sure it should be fine.

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## Gingermick

Dont forget to put some coarse stone inside at the bottom of the wall to help drain any water from the soil. This also needs to be able to get out. So weep holes in your bottom sleeper or something. Water behind retaining walls is the main reason for them falling down

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## oohsam

Gingermick, 
I was just going to put some coarse stone at the bottom, then some AG pipe, and then some more coarse rock on top, covered with back fill. OR is that wrong?

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## Gingermick

Good, just make sure you have an outlet for the ag pipe. :2thumbsup:

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## oohsam

Is the neigbours backyard ok...LOL Joke! 
yeah I'll drain it somewhere. I read that its not good to connect it to your storm water as it could overfill and the water come back up the pipe... 
So its ok to cover the coarse rock with backfill, or does the coarse rock need to go all the way up to the top of the wall for the width of the AG pipe?

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## Gingermick

Probably best if you get some geofabric to cover it.

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## Tubby2

I'm assuming this is the type of thing your talking about.
$37 per l/m seems a bit dear compared to a 100x100 post thats $15-$20 for 2400mm length.
I understand that there will be coach bolts to buy as well but still, does it really work out the same? 
I need to do a retaining wall at the back of my place, about 35 l/m

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## oohsam

Yes tubby thats the stuff. 
The cost is roughly the same, which is about $200 difference in total. Thats hardly much (To me) when I look at the amount im spending on my garden/deck etc to make this sort of descion.  
Im still unsure which way I am going to go...

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## Planned LScape

If employing a contractor to do the job, I/H beam would be quicker and have less labour costs associated with it, as the sleepers just slot in after the posts have been set, but as you're doing it yourself it would pay to tally up materials and see what would be cheaper. But, depends on what will be easier on you to, and what will be quicker and if you're prepared to work on it longer for a particular design style.

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## fenderbelly

you could try steel salvage yards for your I beams.

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## Terrian

> bahahahah sorry bout that. I meant 1.1meters or 1100mm.  
> Thanks for the replys guys. 
> $33 a meter is so damn expensive...Would be cheaper to build it from just sleepers.

  2.1x75 pine sleeper, less than $20 each, you want lengths of about 1.7, 
$33 x 1.7 = $56,  
I am having trouble seeing how steel is going to be about the same price as treated pine  :Smilie:

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## namtrak

> I am having trouble seeing how steel is going to be about the same price as treated pine

  Okay this has been bugging me for a few weeks now, so I thought I would take the ten minutes it takes to figure it out. 
For this example, I am building a hypothetical 10m long fence, which is 800mm high.  Now, given that we are using the same 100 by 75mm treated pine sleepers as the rails, and we need the same amount of concrete, aggregate for drainage and ag pipe etc.  The only point of difference price wise are the actual posts. 
Assuming that we use the standard 2.4 lengths of rails we need 5 posts set at 600mm deep.  
For the steel that would be 5 steel posts at 1.4m long at $30.27 per metre for a sub-total of $212 add another $25 for the cost of the 5 cuts and the total is $237 
For the treated pine posts it would be 5 treated pine posts at 2.4m long at $26.40 each (I have assumed the retaining wall is built for longevity using the standard 100 by 200 sleepers) for a sub-total of $132.  Then we need to add the cost of the galvanised coach bolts.  Once again doing it properly there are 4 per rail times 16 rails at $1.60 each for a sub-total of $102.40.  Which gives a total cost of $234.40. 
Now, I'm not yet finished.  There is an unfactored time cost for drilling, and bolting up the 64 separate holes, the wastage of about 5m of treated pine, and the durability of the steel over the treated pine. 
Make sense?

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## Pulse

Saw those posts advertised in metalcorp brochure today, if I still had it I'd tell you the price! It was sold as a retaining wall sleeper post/ 
Cheers
Pulse

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## Terrian

> Okay this has been bugging me for a few weeks now, so I thought I would take the ten minutes it takes to figure it out. 
> For this example, I am building a hypothetical 10m long fence, which is 800mm high.  Now, given that we are using the same 100 by 75mm treated pine sleepers as the rails, and we need the same amount of concrete, aggregate for drainage and ag pipe etc.  The only point of difference price wise are the actual posts. 
> Assuming that we use the standard 2.4 lengths of rails we need 5 posts set at 600mm deep.  
> For the steel that would be 5 steel posts at 1.4m long at $30.27 per metre for a sub-total of $212 add another $25 for the cost of the 5 cuts and the total is $237 
> For the treated pine posts it would be 5 treated pine posts at 2.4m long at $26.40 each (I have assumed the retaining wall is built for longevity using the standard 100 by 200 sleepers) for a sub-total of $132.  Then we need to add the cost of the galvanised coach bolts.  Once again doing it properly there are 4 per rail times 16 rails at $1.60 each for a sub-total of $102.40.  Which gives a total cost of $234.40. 
> Now, I'm not yet finished.  There is an unfactored time cost for drilling, and bolting up the 64 separate holes, the wastage of about 5m of treated pine, and the durability of the steel over the treated pine. 
> Make sense?

  I see your figures, and wonder why you would buy 2.4m x 100mm sleepers when you want 1.4m for the posts, buying 2  3.0 x 75  and 1 1.8 x 75 would be a cheaper option,   
Working from memory (about 2 years since I was last selling garden supplies), about $30 each for the 3m sleepers & $14 for the 1.8 sleeper, about $74, add your 102.40 for gal bolts, gives $176.40, quite a lots less than $237, but, thats just my take on it (says he who has just used 3.0m bridge timbers and about 2.4m 'b' grades, expensive way to build a wall) (oh yeah, no bolts  :Smilie:  
75mm  will last just as long  as 100mm for the posts (about 20 years if I recall) and a heck of a lot less wastage.
As for the time factor for drilling holes, really it is a non issue for the person building the wall themselves. 
If you really want the wall to last longer than a lifetime you would use steel posts & concrete panels  :Smilie:  (thats the next wall I build!)

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## Planned LScape

Depending on wall height however the 2.4m 75 or 100mm sleepers are the stronger option. Anything over 2 sleepers high I go 2.4 lengths.

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## Tubby2

> Saw those posts advertised in metalcorp brochure today, if I still had it I'd tell you the price! It was sold as a retaining wall sleeper post/ 
> Cheers
> Pulse

  I gave them a quick call and the price was $45 l/m. They come in pre cut lengths starting at 900mm and increasing in 300mm increments. These a Galvanised and 5mm thick

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