Length of posts for Armco used as land terracing ?

[CompoSimmonite]

My garden slopes. Years ago I roughly dug out terraces but never got around to making a wall or similar to hold back soil and finish things off. The soil is compacted and even after 10 + years hasn't moved so have now decided to use Armco as retainer. There are two areas it'd be used and they would require both 2 & 3 pieces stacked on top of each other. Each length is 3.5m long (works out at 3.2m after overlap) and approx. 12" deep so will provide 2' & 3' of depth coverage.

So what is the opinion of how much of the uprights would need to be concreted into the ground for 2' & 3' of soil retention above ?

FWIW secondhand Armco is very cheap - look on eBay and price seems to be £20-25 a length. Uprights however are quite dear by comparison so am still debating whether to use them or cut additional lengths of Armco down.

Cheers

Paul H

 

[mike os]

needs to be at least the same down, so 2-3 feeet

 

[CompoSimmonite]

needs to be at least the same down, so 2-3 feeet

Thanks. That is about what I thought. Intend cutting down 3.5m lengths of Armco to make uprights as cheaper than the Z type posts normally used. It'll all be buried and visible aspect covered in herringbone pattern decking to "beautify".

 

[normspanners]

Just my idea, but because the ground has consolidated well, if you put a length of armco side ways IE same as above ground pieces,and the same orientation but just below ground level, across the next terrace down, if the underground armco was on the down slope side of the posts and the posts lent on the underground armco, you would then have a lot of area of earth for your posts to push against, and therefore not have to dig the posts in so far
also if using armco for the posts but using it 'flat' ( there is ample strength in it )for your posts, do you really need to concrete in ?? because the armco is, what?, 300mm wide?, which wider than the average fence post mass of concrete, after all when 'piling' the piles are not concreted in they are just knocked into the earth.

 

[normspanners]

Just had another idea how about pointing the armco posts and try drifting them in, to save freeing up the earth,and un-consolidating it (is there such a word?)a little effort with a FBH 20 lb sledge but then that would be a lot less than digging FBholes.
I made some galv supports for my knackered concrete fence posts, slid them down the posts and hammered them into the earth which was 300mm deep they went in easily.

 

[CompoSimmonite]

Some Armco posts are "drive in" -

So whilst a normal post would require a plate welding as in the above pic I think just a short length of Armco would be OK on it's own.
Only problem is our ground is very rocky with it being an old quarry so it might be easier said then done to drift them in !

 

[normspanners]

bigger the job, bigger the hammer

 

[mike os]

rocks + really BFH