The contractor surely is suggesting to lay them in a mortar set over the existing concrete right? If so, it works but better be done properly or else one stone coming loose will be very difficult to repair. The surface joints too would need to be well mortared and sealed to prevent any moisture from entering, and don't forget expansion gaps. Laying a gravel base over concrete is an even worse idea IMO. Doesn't compact and creates an impermeable foundation beneath what little gravel base you may have. Furthermore it leaves your entire patio susceptible to any movement experienced by the concrete slab. Gravel bases are used in our climate in part due to their flexibility. In the end I wouldn't do it for a client and if I did I wouldn't warranty it. All that said though, you do have an opportunity to install what I consider to be one of the nicer and more underrated outdoor ground surfaces- reclaimed red brick turned on edge. One of my favorite designers James Van Sweden is big on this as it creates one of the warmest and most transitional (home to exterior) ground surfaces as well as being very amenable to patterned desings. Would need to work with your home and greater landscape though.

I think the thought process was based on 3 things. 1. there is need to access the fireplace ash clean out from inside this space. 2. gravel to fill the pit would be about 28 yards and the source and dump trucks are about 45 min to one hour away from the site here. 3. the contractor wanted to keep his carpenters employed building something. None of these are good structural reasons, I know. But the question now remains: Will it work to support the planned patio of layers of gravel, sand, and pavers for the next 50 years?? The site is on top of a hill, nothing higher for a mile.

We are having a paver patio installed. It will be a rectangle of 20"x20" pavers with 3" of 5/8" gravel separating them from each other as well as the edging around the perimeter. Pea gravel will cover the ground outside the edging. The contractor removed dirt flat across the entire area and compacted some paver base on top, like a rug that is slightly wider than the paver area. He plans to install the edging on top of the paver base. I asked about the base material spreading from the edges if the edging is installed on top of it but the only answers I got were, "You don't need it", "It doesn't move", "We've been in business a long time", etc. -- nothing to actually explain how the edges of a free-form layer of gravel simply never ever move. Is there any validity to his argument? It seems to defy logic but I would like to get other input just in case. Thanks!

If you view any of the 30+ videos on Youtube for building driveway, paver, and similar-application bases, there is not a single one where they do not care about making the sub-base smooth, flat and level. There is a target grade, and they spend a LOT of time to make sure the sub-base is level to that grade and has an extremely dense and flat (and visually smooth) compaction. The purpose of sand in a paver install is not to level the pavers! The purpose of sand is to fill the gaps between the pavers, on their underside, and thereby lock them into place. Of course, you do approximately level the sand layer, but you don't compact it because you want the sand to slip up between the pavers. The additional layer of polymeric sand applied on top of the pavers does the same thing on the top side. Further proof of that point is that in installations where there is a large space between stepping stones, they typically install the stones directly on the compacted sub-base without sand. They fill the gaps between the stones with mortar, polymeric sand, or dirt (depending on application). In that application, the sand over the base layer would not fill the gaps between the stones, so it is not needed.