How many Concrete Blocks

[SortedPlumbing]

hey i am Building a retaining wall in my back garden which in total overall length is going to be 18m and Height of 1.5m(over estimating slightly)

couple of Qs:

Anyone give me a rough idea of how many concrete blocks i will need?
(i will be laying them on their side)

How deep and wide do i need to build founds?

And how deep concrete do my founds have to be?


Cheers in advance obviously building walls isnt my trade !

 

[chessspy]

500
The depth depends to some extent on the pressure you think you may be holding back. If it's just a sloping garden thing then 9" of concrete will do.
obviously if it is in a critical situation then get some calcs done.
Put in some weep tubes to stop water pressure, however I've never seen any water come out from these. Pop some 2" waste at or near the bottom
you may need to chip a bit of block off to get 'em in.
Are you going to face 'em up with anything atractactive? If so bed some 18" lengths of 6" wide expamet in some of the bed joints to hold whatever you decide to use as facing up.
your local adult education probably offers bricklaying classes, or otherwise get a few bricks and have a practice.

 

[chessspy]

wide=18"