Sub base / capping help

[Coop5]

Hi all.

I have read the various faqs on here which are great.

Can someone please simplfy something for me:

I have started to dig out my patio area (10m x 4m) which also needs to be raised.

Anyhow, I have found a good few soft spots and a good few roots meaning I have had to dig deeper down to get to the better clay type base.

This has made in infill greater, so I was planning on using mot1 in layers of 150mm compacting as I go until I reach the desired level.

I have since however seen some pepole discussing a capping layer. I can't seem to find clarification on this, so my question is would this be better for me? More time effective, cheaper? Or should I just stick to my original plan. The depth will be approx 400/500mm

Many thanks all

[Coop5]

This is the area, as you can see the groud all needs taking up. Please ignore the line, purely for initial guide only

[seanandruby]

A capping layer is material placed on a inadequate sub grade and you start your build up from there...membrane, ( if needed ) sub base, bedding and paving material. . You can use any granular material like crusher run, dtp1. Why do you want to bring it up so high ??? Surely a low level patio with steps would be less work and a lot cheaper to do. You would need to build a retaining wall at 450/500.

[Coop5]

Hi Sean.

Thanks for your advice. It's hard to see but the rest of the levels are at the usual 2 bricks below dpc. So I wanted the rear to match. Ie I don't want a step down when walking down the side of the house to the patio.

I am getting a retaining wall built but I always prefer to do the graft myself, so digging out and filling the lot is something I will do (back breaking I know)

I just needed some clarification on what to fill it with. What would be the cheapest yet best option , as I said my intention was to use mot1 but thats a lot of mot1 so if there is a cheaper option then great.

Thanks again

Ian

[jwill]

What's it like 200mm below that turf? Looks like just turf has been scraped off to me

[seanandruby]

Might be 2 below in places but it's a steep gradient to fill. The side of the house will need to be at least 900, so a lot of cut and fill. You'll need to dig out all organic material + founds for wall.
I don't think there is a lot of price difference between crusher run an mot but you could cap with c r and top up with mot, sorry dtp. 75ml layers for compacting. Interesting task, be nice to see finished job. Good luck.

[Coop5]

Thanks guys.

Jwill. Nothing has been dug out yet in this pic. The soil is where I have removed an old greenhouse base (basically slabs on five dabs of cement)

Sean. Thanks mate, yes it will be a large task but I wouldnt be happy with a step down - I don't like to see the brickwork under the dpc either, plus my drains are visible also.

It will be a big job, and I'm going to need a good few tons of hardcore I know!

I'll get some better pics up so you can see what I'm dealing with.

[seanandruby]

Coop, the idea is to see the brickwork 150 below dpc m8. You could lay 2 below and step up at the door threshold level.

[rxbren]

Crushed is around 1/2 the cost of type 1

I vary rarely use crushed as the few times I've had it, its not been the best quality - very muddy with bits of plastic/wood/metal and occasional asbestos in it

[jwill]

As above the norm is 150mm below dpc. The engineering bricks cope better with the constant splash and no danger of damp coming thru

[Coop5]

Thanks again both.

Sorry I must not have explained properly.

I want the level of the entire patio to be at the level of the second blue brick. Ie so two blue bricks are visible.

So my retaining wall will be constructed with this level in mind (plus the appropriate fall)

I think I am going to stick to dtp1 as you say crushed may just be full of all sorts!

[Coop5]

This is my plan (using mspaint) the raised bed idea is going though.

As you can see the entire level allows for the 150mm visible dpc

I just have to get digging now hey