I am building a mortared stone retaining wall and I am wondering on what depth to dig down for the foundation with which the stones will sit on. From what I gather from resarching, they say to dig down to the frost line to prevent frost heaving. The problem I am having is that the retaining wall will only be about 2 feet high, and here in central PA, the frost line is 4 feet! It seems silly to dig down twice the height of the actual wall, but maybe that's what people do? It is also just me with a shovel so I would like to not kill myself digging until the cows come home.

Would it work to only dig 2 feet down? I also plan on using lots of gravel and install drainage behind the wall in the gravel. The wall will be cinder block with a layer of concrete and gravel on the bottom.

And opinions are appreciated!

  • Is the wall decorative? Will anything be on top of it? In other words does it carry any load other than itself? – Tyson Jun 16 '18 at 22:06
  • It is decorative, but it will be carrying the load of the earth behind it (retaining wall) – user41178 Jun 16 '18 at 22:44
  • Oops, I missed that concept, even tho you say “retaining” several times. Two remaining things that will help if you edit into your question are length and possibly a picture of the area. I’ll leave actual answers to those that do this far more often than I, but I had a handyman type build something similar but a little different with interlocking brick, they countered the frost heave problem by pouring a 6” thick concrete footer with re-bar just below the surface. I questioned him at the time but he convinced me not to worry about it, so far it still looks perfect (3years) – Tyson Jun 16 '18 at 22:59
  • I think you're overstating the PA frost line. information I've found quickly online says 6" to 2'. What part of PA are you in? – The Evil Greebo Jun 17 '18 at 0:40
  • I am smack dab in the middle of PA in State College. Pretty much every link I click on when I google "PA Frost Line" says that the frost line here is between 3 and 4 feet. – user41178 Jun 17 '18 at 14:15

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