Pavers on top of concrete

[orraloon]

I've had a browse through previous posts to see if been raised before, but not found.

Client wants to replace old concrete flag patio with Stonemarket pavers, 50mm. Patio only, no vehicle traffic.

Started lifting old flags, uncovered a 150mm raft concrete underneath, on which the flags had been laid using the old 5 spot method. Leaves about 80mm depth between concrete raft and top level.

Reckon I don't want to lift the concrete, as in good nick, it's level, and who knows what horrors lurk underneath. So propose to switch from a flexi sand base to a rigid bed using standard mortar mix, going for a full mortar bed lay as per flags.

That would mean that I'd need to mortar point as well to waterproof it all.

Is this right? Or do I have other viable options?

Cheers for any advice.

[bobhughes]

Have a look at the main site and all will be revealed

[lutonlagerlout]

you cannot really lay pavers on mortar it doesnt work too good
if you concrete edge restraints in ,then you can just lay them on 25-35 mm of compacted sand as per usual
the edgings will stop it moving
cheers LLL :laugh:

[orraloon]

Maybe the question should be 'what's the min. depth sand bedding layer I can get away with?' Looking at 20-30mm across the width, but getting as thin as 10mm above the concrete in one area where a path extension comes off the patio.

I will be putting in solid edgings so paver movement will be prevented.

[lutonlagerlout]

i would have thought 10 mm was "touching cloth " as they say,but 150mm raft is a great subbase,shame to break it out,i normally try for about 30 mm of sand which seems optimum for me,any less and theres a danger of the subase being too high,any more and the blocks get the infamous "tracks " in them
block paving looks absolutely shite pointed ,so whatever you do dont do that mate
cheers LLL