Flagstone project problems

[JKLC]

Just finished a flagstone project at a lady's house... we place sand between the flagstone for filler... the problem is she like the look but not the fact that this provides no structure for walking etc.. it's not a patio and it's mostly a decrative piece more that anything.. now she want's me to mortar in the flagstone..

My question is can i leave this flagstone on a bed of sand and just work my mortar in over that, between the flagstone in place of the sand...

or if anyone has a better suggestion as to a solution...

we can't put it on a concrete base due to the location of a tree and its root not allowing us to dig down deep enough to lay concrete.

[joshua]

didn't you put down a base? thats the big question. you should of used ag. slag. i'm using flag stone for a trailer pad i put down a 5'' base and the pad isn't finish yet. the trailer get put on it everyday and not 1 stone is out of place. that slag hardens and doesn't budge.

[sheshovel]

Don't mortar it it will crack all over the place,is this a walkway,pathway,patio or what?

did she mean to use it when she asked you to do it?or did she just say "I want you to put some pieces of flagstone along here or out there?".
Dont want to mortar it also for the reason of the tree roots will heave it right up.
You will have to remove the stones,dig down and put a compacted base,or build up and put a frame around it and build up your base from there and set you stone in it.
But regardless of what you do the tree roots will heave it anyway sooner or later.
BTW you charge her for a redo cuz she changed her mind from a decorative to a usable flagstone area if that is what she did.