by MickBee »
Wed May 04, 2011 3:00 pm
stoneyboy wrote:jlc,
Just use sharps sand, you can then re-level as needed.
end
The implication behind this advice is that if you only use sand, you will need to re-level from time to time.
On the other hand, if you want to do the job only once, an alternative way is to:
(1) make sure that the subsoil is firm (jump up & down on it)
(2) put down a bed of sand approx 1" / 25 cm thick, & level it to a depth below the slab-top of (25 cm + the slab thickness)
(3) put on a 25cm layer of sand & cement (for a small number of slabs, Lafarge Slablayer is simpler to use & not too much dearer.)
(4) Water the underside of the slab, and ideally coat it with Waterproof PVA adhesive
(5) Water the sand-cement mix thoroughly, and lay the slab.
When you have re-laid all the uneven slabs, don't forget to point between the slabs with a cement-mortar mix - for this too, it is better to prime the edges with Waterproof PVA adhesive.