Wrong bedding? and how to edge

[surface3]

Hi All

I have just laid a patio consisting of 600mm X 600mm flags. I laid them on compacted soil with about 30mm of quarry dust compacted then about 50mm of building sand with no cement mixed in. The sand has been well compacted when laying the flags. My worry is after reading on your site that I might come out the back one day after heavy rain and the flags are floating past me. Will there definitely be settlement due to the bedding material used, i.e. building rather than sharp sand? The site is well drained as it is on a slope.

Also, what is the best method to edge the flags. On one side there will be a flower bed. On the other three there is between 6" and a foot drop as the flags are raised off the original soil base?

Thanks for the help

[Tony McC]

I can't say that the building sand will definitely wash away, but it is at more of a risk than a sharp/grit sand would be. It's too fine and so it is very easy for it to be carried away by any groundwater.

Edging - with a drop of that scale, I'd strongly suggest a Flag on Edge