Phil L wrote:

When you come to relay the flags, rake the sand base level and
sprinkle in a few shovel fulls of cement,[1] you don't need to
mix water with it, there's enough in the sand.
Rake it in to mix it up a bit and lay the flags directly onto
the bed, do'nt use 'blobs' of sand/cement as this just leaves
voids underneth each flag, moreover, this blobbing is no good
IMV (I lay drives for a living) as the rain will simply wash
the sand from underneath the solid blobs leaving each flag
rocking...simply lay them on a dry sand/cement mix and the
overall effect will be a semi-solid bed with flags on top.
You will still get colonies of ants taking up residence but
they will be much smaller nests and will be unable to make much
of a dent on the foundation.


Agree with all that, but there is a common misconception about the "5-spot"
method of laying slabs.

As you recommend, the full bed dry sand/cement method is by far the best,
but can be difficult for the amateur as the bed need to be evenly compacted
and levelling the slabs can be a real bind. Too much or too little bedding
and you have to lift the slab out again. It is a far more skilled job than
it might look.

The "5-spot method" is easier for the amateur as the blobs can be set high
and the slabs gently tapped down to the correct level. BUT, and it is and
important BUT, we are not talking airy fairy fist sized blobs, but big spade
sized blobs that effectively meet in the centre of the slab as it is
levelled down. the net effect is a nearly-full bed of wet mortar.

All professionals I know use the dry or semi dry method.

pk