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I've recently become a first-time home owner, and have inherited an interesting patio crafted from pieces of broken concrete. I like both the look and the recycled approach but I need to make some adjustments. My lack of experience with patios period, let alone this artistic endeavor, makes it difficult to come up with a strategy.
The primary problem is that many of the pieces are unlevel and a wee bit dangerous. Is there a remedy short of digging up pieces and re-laying? Can I buy a mallet and tap pieces/corners in deeper?
Next issue: I want to rearrange a couple of places to create a more natural/convenient walking area. I've pulled up some pieces and can detect some sand in the soil, but not too much. I've read some instructions on the process that indicate the concrete pieces should be sitting in 2-6 inches of sand. Are there variations on this formula? Can I use more soil in hopes of growing thyme (or some plant) inbetween the stones? (One small section of the patio still has some pea gravel in the cracks. I like this look, but the patio gets too much debris from nearby trees and will require constant sweeping. I assume that's how the rest of the pea gravel was lost!)
You can try to use a rubber mallet to level the pieces if they are not too uneven. Anything more than about 1/8-1/4 inches difference, though, I'm not sure you'd have much luck. Can't hurt to try, tho.
As for the base - to do it right, you should have enough of a sand base to both drain water off of the patio and to defray any thickness differences in the concrete pieces. The more irregular the thickness of your pieces, the more sand you should have. In other words, any trip-you-up bumps and dents in your pieces should be directed towards the sand where they won't be noticed and still have enough sand under the thickest piece to let water thru.
To plant between the pieces, fill the cracks in with good soil. The sand is needed UNDER the stones, but you can fill up between them with (almost) anything that will help hold them in place.
Thank you for your insight. Perhaps the sand strategy will become apparent when I actually try it. I can understand the sand as a leveling agent, but I'm not sure I understand its use in drainage (versus regular soil).
These concrete pieces are indeed irregular in thickness — some two or three inches difference, and therefore much heavier. Should I be laying in dry or wet sand? Does it make a difference? How much height should be left above the sand before filling in with soil and/or gravel? Should the thinnest piece of concrete lay just on top of the sand, while pushing (pounding) fatter pieces until level?
Additionally, do I need to dig and position wooden "borders" to frame this new path I wish to create (before pouring in any sand)? It's not the best shot, but I've attached a photo that shows the wood piece I removed in order to extend a walking path. Should I now cut this piece, and use the smaller lengths to frame the area where I'll lay concrete?
And lastly, for the sake of the house this patio butts up against, should there be some slight grading involved in the laying of the concrete pieces (or, rather, of the soil and sand before they were ever put down)?
Sand drains faster than soil, so it tends to keep water from pooling on your path much more easily than just soil. It also only packs 'so much', which means that, even when you pound down the blocks when you place them, the sand won't pack as much as dirt would so that water will still be able to get through. If you just used dirt, you could end up packing it so much that it wouldn't drain.
Wet/dry doesn't make a difference as far as I know except as to how messy you'll get working with it ;-) Though if you can wet it down thoroughly at least once before you start laying the blocks, it will help settle it. (but it doesn't have to actually BE wet when you start laying the blocks). Try to avoid walking on it after that, because you will stir it up again. A little won't hurt, but try to minimize it.
You can lay the thinner pieces right on top as long as you fill in between them with the sand/soil to keep them in place. But twist & tap them a little to make sure the sand under them is as settled as you can get it so that they don't sink later. The height above the sand doesn't matter all that much, since you'll be backfilling with dirt. The cement pieces should all be thick enough so that they won't pop up when you walk on them - I'd say at least an inch or so. Anything thinner will have a tendancy to slip out of place.
Wooden borders are not necessary if you're digging out the sod first - the dirt on either side will hold the sand in place. But you might consider it for a more uniform look with what you already have. You'll need a frame to hold the concrete in place as you mentioned (a dirt-only border tends to end up looking very ragged), but the frame is typically removed once the cement cures. It can be left in place as an expansion border if it's in between 2 areas, however.
As for the grade, a slight grade is never a bad thing when it's next to a house. It can be slight enough that you don't notice it when walking, but enough that water will run off away from the house. This can help empty any shallow low spots that you have (you WILL have some ;-) ) and, if you're trying for a grade AWAY from the house, you won't inadvertantly end up with any kind of slope TOWARDS the house.
Hope this all helps. Let me know how it turns out.
