I have a client that has just returned from Europe and is in love with the pea gravel pathways in some of the gardens over there. She wants to change out a couple of garden room pathways from sand set brick pathways to Brick borders and pea gravel field, so it would seem to be an easy switch. Just pull up the sand set field bricks and remove the sand and replace with pea gravel keeping the mortared borders. I have a couple of concerns. How thick to have the gravel? I don't want it to be like wading through thick sand. What base? Is it OK to lay down on clay or do I need to come in with ABC? What am I missing? Nothing is ever as simple as it seems. Thanks in advance for any help.