[Bob Mariani]

In cold climates with a hillside providing a lot of runoff water problems would a flagstone sidewalk and a flagstone patio be best constructed over a 4" concrete base then set in mortar and mortar joints or best over gravel base, then stone dust then polymeric sand?

 

[ccarlisle]

IMO you'd have to consider run-off and water freezing...#2 would be my bet.

 

[Bob Mariani]

yeah, that is what I was thinking too. Now to convince the client to change from the planned concrete work. I plan to use 4" 3/4" trap rock compacted with 4" drain lines added along the water path. Then 2" stone dust compacted. Add another 1" stone dust to set 1" flagstone and border with Belgium block set in concrete. Then the polymeric sand.