Morning

I need to relay some Indian stone flags that sit on top of a retaining wall as they’ve come loose.

As they’re not that heavy can anyone tell me what sand/mortar mix to use for good adhesion and should I add some PVA?

Thanks

Like you say, the problem with using indian paving as wall tops is the lack of weight , also the mortar doesn’t key to them like a more course/porous wall tops. Try and use a soft grey or red building sand 2-1 mix. Pva would be no use in the mix. If its a particular problem area eg. Being stood on a lot, knocked all the time and it isn’t a long run? You could resin bond them.

Always a problem is you haven’t got weight, surface area or both. Try bonding some “keying material” to the surface of the coping – EML or some light mesh so that the mortar bed can get its teeth into it.

Also wet the coping (face going onto the mortar) before laying

We used a form of epoxy resin on copings the kids kept pushing off at my parents.

Aint shifted since. Perhaps one of the buildery people can shed more light on the epoxy resin used as i havnt a clue 🙂