Retaining wall - Design & materials

[jez]

I am extending my patio and have dug out my garden. I now need to build a retaining wall on 3 sides.The back wall will need to be 1.3m high x 6m long, the left side 1.3m high by 3.7m long and the left wall 1m high x 4.6m long. The ground is made up of solid chalk and flint up to a height of about 0.9m, so I expect good drainage and not much (if any) movement.
How deep will the foudations need to be?
I was going to use a base course of engineering brick followed by another type of brick. What type of brick would be suitable?
Do I need to add piers to strengthen the wall ?
What type of bond would be suitable- English - Flemish?
I will put a waterproof membrane behind the wall but given the ground is chalk do I need a perforated drain behind the base of the wall? Thanks, Jez:)

[Mikey_C]

any wall, retaining or free standing, above 1.2m really needs the advice of a structural engineer. there is some information regarding retaining walls here. hollow concrete blocks with vertical steel reinforcement seem a favorite from a structural point of view but require rendering to provide an aesthetically pleasing view.

[Rich H]

Or you use them for the hidden back of the wall and tie them to bricks at the front.