In message ,
r.p.mcmurphy writes

"The Natural Philosopher" wrote in message
...

I'm on clay here, and simply laying slabs was OK for a while, but
ultimately they ended up sagging and crooked. So I went overkill last year
with deep substrates and sand. It's a bit of a decision as to how much
your soil will compact, and how long you want the things there.

The soil doesn't compact, what's happening (as demonstrated by Charles
Darwin well over a century ago) is that earthworms are slowly but surely
moving the soil (or sand, or limestone - they like limestone) from
underneath your slabs to on top of them.
Go with the flow - every so often, lift them and level them with some
more sand.

have a compactor plate so if i run that over the lawn and make sure its well
compacted...is it more likely to be ok?

The compacted lawn won't grow very well. Plants like their soil pretty
much as spongy as possible, so that water can drain away and air can
reach the roots.
Compacted clay is a good base for a pond or puddle though.

--
Sue ]