Question
I question has to do with laying a flagstone patio in mortar on an excavated soil base not on a slab. How to do this on a slab seems rather obvious, much like laying tile. My question is do I lay the mortar to soil or do I have to put down an compacted gravel type base and then a mortar bed for the stone to set in? How deep does the mortar bed need to be if that's what's needed?

Answer
Hey, Chad.

Personally, I would not try to lay a flagstone/mortar pavement on anything other than a slab. It's just going to crack and fall apart, especially if you're in an area that gets daily rain and sunshine, or an area that gets freezing temperatures. The better the base preparation, the longer the flagstone/mortar will last, so you can take great care in preparing a compacted gravel base, but the time and expense for taking great care in doing that many times is more expensive than just pouring a concrete slab base.

If you have a Home Depot in your area, they have some good books about various types of patios. If not at your home improvement store, stop by Borders or Barnes & Noble.