Retaining Wall

[Dan_574]

Posting a question for a mtae. He has 31m of retaining wall 900mm high double brick. The engineers plans call for a footing 600 wide 500 deep with reo top and bottom and bars coming up between the bricks concrete in the middle. He's looking at 10k. A question for all who may want to voice an opinion.
How about getting the dirt battered back at 45 then putting in a treated pine retaining wall with gal steel UB posts, then putting a single face brick wall in front on footing. Crushed rock on the other side of the wall and a garden bed on top.
Your thoughts and comments please.

[ozwinner]

How long is the retaining wall going to be there??

If only for a short time, go with your idea, if for a very long time go with the engineers plan.

Al

[bitingmidge]

Wot Oz Sez.

P

[kiwigeo]

Hi Dan,

If youre doing your own wall then dont forget to factor good drainage into the plans. Not having proper drainage can lead to significant pressure building up behind the wall and lead to failure of same.

[ian]

Your wall still seems to be supporting a similar load to that of the engineered wall.

Is your mate insured?
It's most likely his house / property / third party insurance company will dump him if your home built wall failed and injured someone or damaged someone else's property.

In general, if your retaining wall will be higher than one of the walls pre engineered for the home handyman see http://www.cmbrick.com.au/retaind_pguide_all.html for an example you're better off staying with the engineer's advice, at least he has to keep his insurance current.

If $10K seems too much, and I have no idea if it is, ask for a cheaper option.

[kiwigeo]

To give you some idea of cost...I had a .9m x 10m engineered retaining wall built recently. Uprights are steel and go 1m into the ground and are cemented in place. One upright penetrated an old septic tank so a tie back was attached to this upright. Concrete sections were inserted between the uprights and wall was backfilled with clean quartz rubble (10mm) and tamped down. Total cost was about $8000 and it was about three days work for 3-4 people.

The wall wasnt engineered but general design was visually checked by an engineer during and after construction.

[vsquizz]

31 metres of engineered retaining wall in reconstituted limestone blocks, TOW 900mm: I would do this for less then $6000.00 (typically) but it depends on the site and earthworks required. I don't know the cost or availability of 1 metre re-con blocks in Mexico. For shear mass the re-con limestone floggs a brickwall in outright retaining and there is no footings to pour.

Cheers

[Gingermick]

We allow about $650/m² for the wall and a separate rate for the footing for link block walls. The footings usually aren't anywhere near as sunstantial as 500x600, but these walls have a fabric reinforcing that runs back into the ground. ie they require more excavation.
I work for a large consultant engineering firm and we do lots of retaining walls in new estates.
I just finishhed one with a treated pine wall. I kept the wall below 600 though to avoid the need for certification from the other end of the office.

[Eastie]

On the two plans I've got the engineering spec is for a cavity (for scoria drainage) behind the wall of no more than 300mm. Both specify if the fill area exceeds this the engineer must be consulted. Taking it back to 45 would add a fair bit of work to an already large job.

[silentC]

If he can batter it back at 45 degrees, why does he need a retaining wall at all? Just throw some rocks and creepers on it and it will look like part of the scenery in 12 months or so. Or terrace it. There's more than one way to skin a cat...

[Gingermick]

The engineers must have determined that the angle of internal friction of the soil was such that the batter would not be stable .

Would be a ####### thing to maintain too.

[silentC]

The engineers must have determined that the angle of internal friction of the soil was such that the batter would not be stable

Yeah, they must have - they're good at that type of thing

It's 900mm high, right? Nothing to be built on top of it? I think there's a tendency to look for the most complicated solution when a simple one will do. I've got one of these to build soon, and I wont be getting any engineer's design for it. I'll batter it back (probably lower than 45 degrees though) and maybe throw down some T/P logs pinned into the bank. Plant some creepers at the top and walk away.

Amazingly these sorts of slopes occur in nature and they don't need retaining walls to hold them in place

[bitingmidge]

900 mm @45° is probably OK for just an interlocking mulch like pine bark or whatever.

I agree completely Darren, at the Home of the Biting Midge, I dropped a toe of sandstone boulders to take up the first 400 mm or so, and battered a little shallower (a bit steeper than 1:2).

A year later the planting has taken over. One or two spots have been rebuilt a couple of times after heavy rain, but it works fine.

In a previous life we used 2-3" diameter saplings pinned across the slope to hold the mulch till the plants took over. The timber rotted out in two or three years, but by then they weren't needed.

Cheers,

P (who thinks retaining walls are for railway cuttings, not landscapes!)

[vsquizz]

900 mm @45° is probably OK for just an interlocking mulch like pine bark or whatever.

P (who thinks retaining walls are for railway cuttings, not landscapes!)

Well you "Batter it off" guys jus keep it up . I should be able to buy another excavator by the end of the year while "Batter it off" is prevalent . Come on, logs??...plants..are you guys hippies or poofs or something?. Not to mention the white ant treatment guys should be paying you as well .

(Cheers from squizz who just finished excavating a "She'll be right" "Battered Off" boundary line in preparation to instal a REAL MAN's Retaining wall. )

[bitingmidge]

..are you guys hippies or poofs or something?.

Oooooooh you are soooooo sweeeeet!

My lips are pursed just thinking about you jigggggggling up and down on those big black rubber tyres!!



P