Stonemarket truestone flags dont stick

[Fox123]

Has anyone had similar experience with sandstone flags not bonding. My 70m2 patio was laid last November using Stonemarket Truestone flags (quartzitic sandstone). I'm now finding flags havn't bonded to bedding layer or grout. Some flags move when tapped firmly from above. Most of centre slabs showing fine cracks along either side of grout (ie. along edges of flags). Edge slabs lift away cleanly & grout taps off easily. Was laid on 75mm sub-base plus full bed wet 5:1 sharp sand/cement. Grout 3:1. No frost or sun when laid. I didn’t apply PVA or anything to underside of flags. Manufacturer suggests this "might assist adhesion".

My question is, will a make-over (ie. regrout & fix edge slabs to pre-laid bedding layer with epoxy or PVA/neat cement mix) give reasonable length of patio life or should I remove & clean off the flags, remove bedding layer & start all over again. Anyone's experiences or advice would be most welcome Fox123

[paul ush]

There's some advice and similar experiences if you do a search - I was looking for something else but found some answers to your problem here - not sure if this link will work!

http://ext.pavingexpert.com/cgi-bin....ing+gun

[Fox123]

Thanks for that Paul. Sorry so long to get back.

[hseagle]

A bit late in replying but I've just finished laying my Stonemarket Trustone patio & had to re-lay about the first third due to rocking and lack of adhesion. Some of the rocking was due to my father-in-law (the original bodge-it-yourself man who insists on the 5 dab method) standing on the slabs, testing them for rock, within a couple of hours of them being laid. I could have walloped him with my rubber mallet but I digress....

But I also laid them on exceptionally hot days, probably too dry a mix, probably didn't bed them down enough (the technical expression escapes me).

I couldn't see any other way than to dig out and relay on fresh mortar. I tried your patch-up method as a test on one slab but no joy. When relaying, thankfully in cooler weather, I used a much wetter mortar mix and had the mild "floating" affect described on this site - not too bad to cope with though. I also coated the slabs with a neat cement, pva and splash of water mix. I wasn't sure if that was right but I think it helped. This time after consolidating and levelling with the old mallet I could really feel the slabs sucked into position and feel a lot more confident they will hold. Time will tell.

I had quite a long delay before pointing but still veered towards a drier mix to avoid staining so I am less certain about it. I did use a pointing bar thingy (pricey for a bent piece of metal) and it was worth every penny - much easier to strike the joint firmly avoiding any gaps and get a more professional look.