Bradstone polished sandstone lifting - Help needed for remedy.

[Design Rob]

Hi guys, I am an established garden designer of some 23 years experience, working with a small group of quality landscapers. Last December we laid a considerable sized terrace in Bradstone's Polished Natural Sandstone paving, a product we have never used before. None of the work was carried out at freezing temperatures, all the areas were covered at night. The flags were solid bedded with the recommended 10mm joints, (a pain in itself as although the flags are supposed to calibrated there was up to 5mm variation). The sub-base was granite millwaste between 100 and 150mm deep, compacted in layers. This has not moved. The whole terrace has been laid to a gentle camber to allow run off.

Recently (March - April) a large number of flags are detaching from the bed, and although still in position have that hollow sound when walked on. Lifting some flags to see what's happened the underside of the flags seem very wet, almost as if the whole flag has been porous and allowed water through.

In all my time in the landscape industry I've never seen anything like this. Here's the rub, the client has said lifting and relaying is not an option due to cost.

Does anyone have any ideas for treating this without lifting and re-laying. Personally I can't see anything working as once detached the flag will always move fractionally, he's asked if we can get a product that can be applied through the gaps and then re-grout afterwards, (almost like an adhesive?)

Any ideas would be hugely appreciated.

[Design Rob]

Apologies, I thought I'd posted this in Paving and now can't seem to move it (Newbie)

[bodgeitandscarper]

Your not related to me by any chance!!

[GB_Groundworks]

some of the resin based products are in liquid form, romex etc but without a solid base your gonna struggle to fill all the voids and make it solid.

re the client, is that your client i.e the landscaper or the patio owner as surely the landscaper should be relaying them at his expense as they aren't fit for purpose.