Since the existing patio is on a granular base (as opposed to solid concrete) I would absolutely, positively NOT consider any mortared work on top of it. The reason is that the earth is a flexible surface. Though it moves so slowly you can't see it, it is doing it nevertheless. If you were to mortar flagstone or thin brick on top of it, this work would effectively be only as thick as the mortar that glued it on ... 1/2" maybe (?) It wouldn't be thick enough to support itself as the earth underneath shifts. If you're going to mortar something on top, you need a 4" solid concrete, driveway-like base (3 1/2" actual) that will not flex at all. But you could go over it with regular thickness pavers on sand IF you insulate the two layers with an inch of sand. (This is predicated on knowing that the existing base is of SOLID compacted material. Since it's been there a good while, its present shape is a good indicator of how solid the base is.) I would go so far as to say that if the present patio was perfect condition -- smooth, of perfect grade, and all slab joints perfectly matched -- you could go over it without the sand insulation. But it's not likely that it's that perfect. If you go over it, one thing you'll need to pre-plan carefully is the finish grade. It looks like your grade might end up being too high. I don't know what all the holes at the foundation are for, but they're probably not wanting to be blocked. If you need a lower grade, sell all those slabs on craigslist (someone would probably love to have them ... they look like step treads, BTW) and build directly onto your already existing base.

You seem to have thought through the construction correctly, with edging and sand. You do need to compact the dirt so the section over dirt doesn't sink relative to the section over concrete. Of course if it does, you just need to lift the pavers and add more sand. KarinL

Wren- Yes!! That's sounds great. I'm planning something similiar myself. In the meantime, I expanded our front stoop by using those concrete one foot square pavers. The red and grey ones. We just have the stoop just next to the driveway, no walkway, and the stoop wasn't big enough to navigate comfortably when guests come in. I dug down about 5-6 inches, hauled away that dirt, and tamped in some sand. Oh, almost forgot, my husband cut some edging for it from pressure treated lumber I scrounged from someone's trash. (Two rows of two by fours, mitred corners,screwed together) I decided on the edging to help keep things neater. I think we put the edging in first, then the sand. Be sure to pack the sand down firmly. My husband took a two X four (about three foot long, comfortable for me to work with,) and screwed a one foot square piece of plywood to the bottom for my 'tamping tool.' Then I set the pavers in place. Oh, I think I layed the pavers out before hand, so I knew how big to make it. But we were only doing a small area. Then I swept sand into the crevices. It's been about five years, and not a problem. No frost heave, nothing. It shovels easily in the winter too. Mine is on the north side of my 1959 ranch house. Even dear husband, who throughout the whole project said it wasn't going to work, that it would frost heave, that it would look bad, has since admitted it worked well. Those red and gray pavers aren't the most beautiful, but the price was right, they have 'aged' a bit, being on the north side. They blend in nicely with the existing stoop and driveway. The only thing is ants always tunnel under the pavers, so I sweep sand off during the summer. After five years, the whole thing has sunk down about an inch-inch and a half, so it's no longer level with the driveway. Amazingly though, it sunk completely evenly. This summer, I'll pick up the pavers, add some more sand; it should be good to go for a few more years. I'm thinking if I use some gravel, maybe the ants wouldn't be able to 'excavate.' I don't think I'd use pea gravel, as it might shift, being round. But see if you can find some sharp gravel. (I'm not sure what it's called, but a gravel yard would help. Probably just sharp gravel.) Good luck with your project. Someday, after we remodel the entryway to the house, I'm going to do that picket fence, with the patio behind the fence :-) cantstop

I don't know if I can say if it's a good idea or bad idea without knowing a little more on how you plan on using the pool or more info. I really loved the look of coping only, and wanted to save my grass. I think it's a scary thing to look at your nice yard of grass and know that so much will be torn up. But after it's all over, everything will go back together, and it will look nice -- even with decking! I just posted some pics of my finished pool last night. We opted for one side of coping only. We have not yet played volleyball in our pool or any type of game. (We have a toddler.) But I expect that side of the pool will be annoying when the ball gets out of bounds and tracks mulch into the pool. I'm glad that we went ahead and did a large deck on the one side to tie into our existing patio. It just made sense with our layout. But it gives us a chance to set up a lot of tables and chairs for a large group or party. Which we did make use of on 2 occasions last year alone. Our coping side only is not grass. But I can't understand how you don't end up with a lot of grass clippings in your pool when mowing. I tried to plant ground cover plants like potato vine that cover the mulch. If you are "in love" with the look of grass surrounding, then nothing may change your mind. I would do what you love, and you think you will enjoy looking at so it's your peaceful oasis in your backyard. If you are doing it to save money on decking or just a whim, then I think it's a bad idea.