I want to put limestone blocks 2x2x5’ for seats in a 10x12, 4’ deep fireplace area, I rented a digger and dig a good amount and plan to put 6” of bass or minus then the blocks around the pit.. will it sink over time?

I need it to drain and stay put right?

  • Hmm not sure how much depth you'd need here, but for strong bases for heavy stuff you lay gravel in 3" "lifts" and pack each lift with a packer before adding the next. A properly packed lift feels hard like you're standing on concrete. More lifts and more packing give more resistance to sinkage. I definitely wouldn't think about less than 2 3" lifts, but I'd consider more. Nature of the gravel provides drainage and can be connected to weeping tile if you wish.
    – K H
    May 4, 2021 at 11:24
  • Well, yes, I presume you "need it to drain and stay put". Are you asking if you need drainage in order for it to stay put? Please feel free to edit your post to clarify that bit. Also, are those blocks 2' x 2' x 5'? They're mighty big and heavy. I'm no expert by any means, but I'd think that 6" of gravel may not be enough to support that - I'll let others with more experience chime in, though.
    – FreeMan
    May 4, 2021 at 11:58
  • 6” is a lot of rock when compacted. I use 3/4- in my horse stalls and even our big boy ~1800 lbs doesn't have problems with 6” and a 1” rubber mat over that, your soil conditions could require more or not even need an inch it all depends on what is there.
    – Ed Beal
    May 4, 2021 at 13:41


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