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I plan on laying a patio, and I would like it to be permeable. After some book and internet research, I think I have a plan that will work, but I would like to have someone with more experience confirm it. In particular, I would like to use compacted 3/4" limestone chips with no fines as a sub base, with an inch of sand on top to set the pavers in. I will space out the pavers a bit so that water can drain through. I will rent a compactor for the project.

Here is a picture of what I have in mind: permeable patio base

I gather that this design isn't the standard practice of using crushed limestone with fines, which will compact to a firm base. Will my base hold up over time so that the patio stays flat, or should I give up on permeability and just use crushed limestone with fines?

It is probably relevant to note that this is in the Chicago area, so we do have freezing conditions in winter. We have quite heavy clayey soil here. The patio will experience only foot traffic.

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  • that should work fine for light-loads, albeit likely a bit more costly than other base materials. Limestone is about the best material (save shells). You can add fines if desired by over-handling the material, but they are not needed to matrix such a small grade (0.75"). I would also compact and add lime under the base, or go to 6", or add 2" of a courser sub-base under the chips; 4" is slightly skimpy IMHO, even for calcite...
    – dandavis
    May 23, 2022 at 18:24
  • @dandavis Thanks! How do I "over-handle" the gravel? I expect it will get dropped at one spot on my property and I'll have to wheelbarrow it over to the patio site. Could that be done in an over-handling manner, or do I need more serious tools? If you make your comment an answer, I'll accept it. May 30, 2022 at 21:40
  • handling would be stuff like moving the pile, loading, and unloading, etc. For a consumer, that's a probably lot of work. you could spread it out and drive over it to decrease gradations. You could also mix in a bit of smaller agg like course sand or cheap "lava rocks" before compaction. You probably don't need fines, but they might be good if you have big roots under the patio as fines will lock the matrix to guard against push-up (the direction of force a draining mesh would be weak).
    – dandavis
    May 31, 2022 at 4:35
  • you might also want to extend the base several inches out into (under) the lawn, which makes the brick edges resistant to curl-under and lessens whole-patio "hammocking" where frost cleave is an issue; it's more comfortable to sleep on an over-sized mattress...
    – dandavis
    May 31, 2022 at 4:39

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