add or remove DG. if your lay out is on a slight slope or in my case sloping slightly toward drain I used my thicker flagstone towards one side. I actually compacted my DG piles lightly into the grooves. figure better compaction the stronger. I did not see in this video if he added / used the stabilizer? a liquid or dust is available which hardens the DG. I will have a video coming out soon- hope it does well.

it all depends on which flagstone you want. thickness and how thick you want your grout lines. anywhere from 300-900 a ton. Tone covers 80-120 square feet. DG is about 60 a yard. (always buy by the weight because if you bag it it cost more. same with the baserock class2 that can go underneath DG which is about 40 a ton.