Patio Help please

[DAZZA76]

Hi,

I'm new to the forum so hi everyone!

I've been searching the web trying to find specific help but can't find anything.

I am laying a new patio but need to increase the ground level by around 12inches with hardcore (this is old material I had laying around the garden such as bricks and concrete from an old patio). I am building this up in stages.
The first course layer of hardcore went down fine as they were going down onto earth, but as I put more over the top of it it become quite wobbly/unsteady.

I intend to go over with sand and then whacker plate then with type 1 before my slabs go down.

My questions are:

Is it ok for the the upper layers to be wobbly? (sorry if this is a silly question)
If not how can I get around this?
Will it notice once the sand & sub base go over it?

At the moment I am putting down slabs and concrete and giving them a good whack with a club hammer, the pieces are that small, how big should they be?

Thanks for any responses in advance.

Dazza.

 

[r896neo]

Trying to add sand or type one on top of rubble like that will result in settlement. The best thing in your circumstances would be to get all the hardcore in, then top it off with clean stone such as 10mm, rake this into the gaps and plate the lot a few times. Clean stone and rubble are good fill material as long as they are restrained on all sides and cannot spread and also as long as you don't put anything on top that can filter down into the gaps.

So once this is done lay your slabs on a full bed of mortar. This leaves nothing to filter down and cause settlement.

Or if you are block paving as a second best option you should lay a good quality geotextile membrane over the entire area and use your type one on top of this as it will not filter down through the membrane and sand and pave as normal.

 

[DAZZA76]

Thanks for your reply, so you think its fine to keep on going even though, underfoot it feels unsteady and this can be remedied after? I just don't want to waste lots of time and effort if the end result is not going to be good.

It is being supported all round, I just need to raise the ground level of a tiered garden.

I saw on another post to water sand in the fill the gaps, Is this a similar solution to the problem?

Thanks

 

[r896neo]

does it feel wobbly side to side as if its moving around if so that's fine and plating and infilling with small clean stone will stabalize it. You need to be Wackering it as you go in say 100mm layers.

If however it feels wobbly as in it feels spongy that is not fine and would imply the ground below is too soft.

Spreading sand over hardcore and watering it in is a bodge, it doesn't matter if some people say it worked for me, its still a bodge and likely to result in settlement.

 

[DAZZA76]

Yes it's wobbly side to side, there's no real give in it as such just didn't want to get it all down, then wack it down for it to still be moving. The hardcore pieces are around quarter brick size is this ok? Will 10mm pea shingle be ok? Thanks

 

[r896neo]

try and add layers rather than a single fill. So some bricks smashed up then gravel compact it, same again etc.

10mm cut stone would be better.

 

[DAZZA76]

That makes sense. Thanks for your advice I'll let you know how I get on. Cheers. D.