Driveway kerb - granite setts - Specification for laying

[speedycar]

I have a pea shingle driveway bordered by lawn and want to edge the drive with a kerb of granite setts.

I am concerned that they should be laid on a solid foundation. The driveway is old and the sub base is just compacted stones and clay.

What should I specify to the contractor or expect from him?

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[seanandruby]

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