Sub base advice

[boardman411]

Hi All

First post after reading a lot of the website.. I have a question that maybe someone can advise me on.

I'm in the process of laying a new patio and have a query around my sub base. The Edge of the Patio will have a step down onto the grass of around 6- 8" .. As my patio will consist of a circle kit, which forms part of the edge and will contain some curves finished of with a sett to edge.. How do I build my subbase if I don't have a permanent edge to start of with (if was a straight end that would be easy) do I just extend my subbase past the point of the patio and cut in, once I've layed my circle kit.. as the circle kit may require some adjustment when being laid, so a boarder cannot be laid first and then infilled with Type1. Any advice would be welcomed. Thanks, Shaun.

[seanandruby]

Build a low retaing wall maybe.

[rxbren]

Either raise ground to suit or you'll have to build a wall or slab om edge to make the radius

[boardman411]

Don't want to raise the ground, that's too much work.. Probably need to work out the exact perimeter and build a retaining wall to the height of the subbase.. I was hoping to get the sub base laid before the slabs/circle kit turned up.... but it all depends on the position of the circle kit.

Might be easy to wait for this to turn up, then dry lay the circle kit and work out perimeter/edge and build a small retaining wall afterwards. Or, thinking about it - I could build a rectangle and fill with MOT and then extend the sub base for my curves etc once the kit has arrived (so that 90% of the base is then completed ) As it's more or less a 4m x 10 rectangle.. I think I might have found a solution, by sharing the issue.. I can use my old patio slabs as a retainer, sunk into the ground to create my perimeter..

Thanks,
Shaun.

[seanandruby]

Problem with retro building the wall you could undermine your finished work. Will your old flags be thick enough as a retainer ???

[boardman411]

I believe they will be (25mm thick) buried in the ground. It's only got to support 75mm of subbase.. Remember that once I know where the position of the circle kit will reside, I can then extend the sub base on the other side and edge with another small retaining wall..

[seanandruby]

Seems a cack handed way of doing it to me, temporary works is time consuming and costly. Why don't you make a trammel from circle centre to edge and build the wall to the correct dimensions alliwing for a 20/30 ml over hang at wall edge. That way your only building one boundary and less chance of differential settlement.

[boardman411]

Thanks for that, never heard of a trammel before, I now know what this is... Okay so I can make one of these and plot my edge.. Ta for that.

[seanandruby]

Your welcome.