Fitz wrote:
Phil L wrote:
Fitz wrote:
I've been googling for this but I seem to have lost my mojo.

I'm going to be laying a patio soon and plan to use a 75mm layer of
compacted dtp1 on top of soil. Then bedding layer and then flags.

The thing I can't seem to find is any indication of how thick the
uncompacted layer of dtp1 should be

It doesn't go down very far so don't go berserk with it!

For a patio I would use only an inch or two, just as a firm base for
your sand/cement mix, to get 50mm all over (prior to whacking) use
trammels....two lengths of 50mm timber down each side, fill in with
hardcore, then run a trammel (another length of straight timber)
across the top of both (like a letter H)so that the thickness is
even and the surface is fairly flat,

HTH

Thanks for the info - exactly what I was after. I'll probably aim for
about 75mm uncompacted then see where it ends up.

Presumably if this stuff sets up as hard as described after
compaction, once you take the trammels away you don't have to worry
about the edges falling away? I've been wondering if I should use an
edge stone to provide a boundary around the edge of the sub-base.

The edges will need support yes, either kerbs or filled in with concrete
later, they will cave in after the trammels are taken away, but the idea is
to s-l-i-d-e the trammel out and infill it using a trowel, so that it's all
level(ish) prior to whacking it.
The hardcore won't be as hard as I mentioned above using just a whacker, to
get it so compact you'd ned a vibrating roller, although this is overkill on
a patio.
It doesn't 'set' at all, ever, not that you'd want it to because it needs to
be porous.