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Some retaining walls from the home improvement store stated that Maximum Wall Height is 2 feet. For example, Tranquil Olde Manor Concrete Retaining Wall Block from Lowes. My question is that why there is such limitation and if I can do some "workaround" to get it to stand up for 3 feet instead? I mean if I glue them and have proper crushed rock / drainage, I don't feel like 3 feet would cause any issue.

Can you give me some suggestion on why or why not? Thanks

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  • I think they must be worried about liability issues, I have seen similar walls 4' high. – Ed Beal Jun 1 '16 at 13:06
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    You likely want to go with 6" or 8" blocks for larger walls. Alternatively, you can stair step your walls. – DA01 Jun 1 '16 at 14:50
  • What was your actual solution to this? I am running into the same issue. – eaglei22 Apr 24 '17 at 16:43
  • @eaglei22 My wall ended up to be around 3 feet but I installed the first one completely buried below soil level. When I stacked another one, I use construction adhesive to make sure they don't move. Behind the wall, I put lots of gravels and landscape fabric against the wall. Finally on top, I put the cap blocks and cement them together. My wall "curved" a bit so they are not one big flat piece that could fall over. They are like L shape. – HP. Aug 29 '17 at 4:56
  • Ah okay thank you. I had did something similar as I had finished my wall already as well. The only thing I did differently was put drainage pipe behind the wall to reduce any water build up. Now the only issue I have is water sitting at the bottom of the wall and puddling up since it's clay soil. So now I have to add some sort of drainage there too. -_- – eaglei22 Aug 31 '17 at 15:30
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This is about load bearing and claims. The pressure associated with 2 ft of dirt is probably well within the load bearing specification of the blocks in question. 3 feet may not cause any issue, but you cannot hold the manufacturer liable if it collapses and/or if someone gets hurt.

If you exceed the manufacturers specifications an inspector might have a problem with it too. I would recommend adding weep holes, french drains, and possibly a deadman. And since much of the weight comes from moisture, the backfill could be gravel, to improve drainage. In fact there are lots of ways to shore-up a retaining wall, but the onus would be on the "engineer" if something were to fail.

Here's a good picture of some retaining wall features. Source: http://www.fairfaxcounty.gov/nvswcd/youyourland/soil.htm

enter image description here

Edit- A tie back is used on block walls. Screw types and anchor plates are common, but there are probably many ways to accomplish the act of tying or holding the wall in a similar fashion.

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  • Good diagram, but note that one is for timber which is often a bit different than block walls. Block walls don't use deadman and are typically stair-stepped so each block steps back from the one below. You'd also want a drainage plane along the full height of the wall with (ideally) a french drain if need be. As an aside, I'd always suggest river rock rather than gravel as the drainage plain fill. – DA01 Jun 1 '16 at 14:52
  • @DA01 Oh, semantics... you got me. A tie back or anchor is used on block walls. – Ben Welborn Jun 1 '16 at 15:04
  • Maybe it's a regional or height thing? I've never seen that as a recommendation nor requirement for residential block walls in the US under 4'. Also, it's not so much semantics as entirely different materials. (That's not to say it's not a good idea to have one!--just that I haven't seen them built that way) – DA01 Jun 1 '16 at 18:12
  • @DA01 Yeah, 3ft is minor... I probably wouldn't bother unless the ground was pretty steep or shifty. A deadman can be stone... the defining characteristic of a deadman is that it's long - not that the material is wood. And I don't see why a log-deadman couldn't be used on a stone wall or why an anchor couldn't be used on a wooden wall. I'm sure it happens. – Ben Welborn Jun 1 '16 at 18:48

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