Laying flagstone

[tsanders]

Can anyone give me feedback.
I want to lay brick / flagstone over both an existing concrete slab and an area with gravel.
Can I tamp the gravel level to the concrete slab then put 1-2 inches of sand over everything and lay the flagstone?
I really don't want to (a)- rip up the existing concrete or (b)-lay down more concrete to match. Would drainage be an issue if I just used sand on the concrete pad or should I use a mortar mix for that part and sand for the gravel area?
Your thoughts would be greatly appreciated!

[Stonehenge]

The odds that you are going to have an issue with the flagstone at the point where the base transitions from concrete to crushed stone is pretty high. You could mitigate some of those odds by attaching a densely woven geogrid (like Versa-Grid) using tapcon screws with washers to the concrete and extend it several feet into the crushed stone base prep. But that's not a perfect solution for your situation. The perfect solution is one of the two methods you mention (a & b).

I'm not a fan of taking a shortcut on an installation because there's too much work involved in doing it right. My suggestion is to do A or B. A would be my first choice.

[tsanders]

Thanks
I figured as much.
If I did lay more concrete first, then is a mortar the preferred way to go or is sand on top acceptable?
The concrete slab is still in great shape. ie an existing smooth top patio and is about 5-6 inches thick (15'x12') so ripping it up would be pretty intensive

[tsanders]

Sorry, One more thing.
If I lay flagstone on the concrete slab, can I just put sand on it and lay the stone on that or should I use mortar mix.
I've read no less than 50 forums on laying flagstone and they all say different things.

[HardDaysKnight]

Mortar the flagstone in. Flag comes in varied widths and mortar compensates for that. Sand on a slab for flagstone makes no sense to me. You will have a better and an easier to-do project with mortar.
Good Luck with it.... Johnny.