Help needed with retaining wall and drainage!

[Poppy27]

Hi

I have a big raised soil bed in my back garden that I would like to patio. I've dug out the foundations but have found that the existing retaining wall is just sat on top of the soil - so I need to rebuild this. Can anyone please provide any hints and tips of how I do this please? Do I just start to build a wall next to the raised earth until I reach the same height as the existing wall (having removed it first of course?). Once this has been done, do I then put down the foundations for the patio?

Also, I'm unsure what to do about drainage for the patio. The raised bed is surrounded by thick concrete so I have no easy access to the only drain (which is next to the house). Does anyone have any suggestions about what to do regarding drainage? I'd like to slope the patio away from the house but where will the water go? I have attached a diagram of my garden layout to make it easier to see what I mean.

I haven't undertaken a project like this before but would really like to give it a go to save money on someone else doing it.

Any advice appreciated. Thanks

 

[studips]

well, if i'm understanding your situation right, then in your position i would:

remove old wall, dig out a foundation (say 350 to 400 mm wide, having dug down to firm ground), set 9" hollow concrete blocks on the foundation and face with something atractive, or for lighter duty use medium density concrete blocks with a facing brick to make a solid 9" masonry wall.

9" hollows allow you to have rebar set in the foundation and infilled with concrete - the height of the wall is a concern as well - how high is it?
Always remember that although the soil retained may not be dynamic, it still can exert pressure - the wall has to be up to snuff.

personally i go for a 1:6 cement ballast foundation, for a retaining wall i might set some rebar in the foundation - i'm a bit paranoid about things moving and call backs

weep holes at the bottom of the wall are a good idea (even if the soil behind is covered by patio.

A soak away should be used to lose the water if you can't move it to a bed or other soil area - you're not supposed to discharge into the drains. soak away crates can be had from your local build centre for a patio, maybe 2 crates would do (that would take around 400litres of water for slow dispersal to the ground below).

you should google 'pavingexpert' and read through aj mccormacks site - there's lots of really good and correct information in there!! dpcs, sub bases, mixes and so forth.

 

[r896neo]

The most important factor for any advice is the height of the wall?