Advice please on best approach to deal with this failing garden wall

June 22, 2018 7:13 PM

These 3 images: #1, #2 and #3 show the current state of my front garden wall which is about 7 years old. It's not looking good, and so I need some advice.

This was done by a professional landscaper who did a much bigger job for us which is now about 10 years old and shows no problems at all.

The pro has since moved out of the area, and I can only assume that either his crew made some mistake on this smaller job they did for us, or the odd layout of our front garden really didn't allow for an ideal durable solution, or something else. It originally looked much better than the landscaping timbers that were there before.

In case it's not obvious from the pictures, it seems to be pulling apart from the top corner on the short return run to the house. Please ignore the ancient landscape lights, they will be replaced as part of this project.

My main question is: For those who have some experience with this kind of thing, what would you do if this were your wall?
My sub-questions are:

1. Does it appear to be cosmetic or likely to fail completely at the worst possible time?
2. Is this the kind of thing where all the plants, soil and mulch have to removed (by shovel), wall rebuilt, etc. or are there other alternatives?
3. If I engage a new landscaping professional to redo the job, any suggestions to avoid a repeat or have a better result (different material?)

This is the New Jersey suburbs of the Philadelphia area, so we get lots of snow and freezing rain in the Winter, if that helps your analysis.

posted by forthright to Home & Garden (9 answers total)

Best answer: Looks like the substrate under the part by the steps is softer than that under the short return to the house, so the long part is tilting.
1. I'd consider it cosmetic.
2. All the stones would have to be removed, and the substrate filled and compacted. A mechanical tamper is about 12- 18" wide IIRC.. A plate compacter is smaller, but isn't going to get the substrate as well compacted, and will wear someone out.
3. Compact some stone into the earth under your wall, with a mechanical tamper.
posted by rudd135 at 7:28 PM on June 22, 2018

Best answer: I agree with rudd. The soil has settled and the stones have shifted. Possibly the original landscapers didn't tamp down the soil well enough under that section of the wall, or possibly this is just what happens after ten years of freezing and thawing. Cosmetic for sure; any further settling will likely happen at a slower rate than what's happened so far, and it doesn't look like the wall is currently anywhere close to actually failing. What I would do is just shift the stones a bit so as to redistribute the extra gap and make it less obvious. Actually, that's a lie—what I would actually do is nothing, but if I were going to do something then I'd try shifting the stones. The right way to fix it would be to have a landscaper or mason come and re-do the wall, adding some fill underneath that section and compacting it before rebuilding. However, I personally don't think it's worth it. It doesn't look perfect, but what does?
posted by Anticipation Of A New Lover's Arrival, The at 7:59 PM on June 22, 2018

Best answer: There may be subsidence under that corner that is contributing, but I think the main problem is that the overlap pattern was not well thought out precisely where the split is forming. I would try taking off the top two stones on either side of the split (corner stone and the one next to it, maybe even the skinny stone underneath those two on the short side). Then use a sledgehammer (or one of the stones you took off) to pound the corner stack back toward the house as much as you can. Finally, when you reassemble the top two stones, swap their positions so the long piece is in the corner and overlaps more with the layer underneath.
posted by drlith at 9:18 PM on June 22, 2018 [1 favorite]

Best answer: I can't quite tell whether the greatest degree of displacement is due to tilting or to the fact that the unmortared bricks have slid with respect to each other from the bottom up, with the top course of bricks displaced the most.

Either way, I think you could correct the looks almost completely by digging a narrow channel right next to the wall on the inside and all the way to the bottom (some of which you'd probably have to do anyway to replace the lights), and moving the top three courses of bricks toward the house until the gaps at the corner are closed up, and the edges of all four courses are aligned.

And I think the result would be perfectly stable.
posted by jamjam at 9:19 PM on June 22, 2018

I've also seen people in Seattle put angle iron with 2-3" wide shelves at the corners of brick retaining walls for extra support, though I think that would be superfluous for you.
posted by jamjam at 9:34 PM on June 22, 2018

Best answer: That looks perfectly fine to me. I'd live with that for a long time if it were mine. That's not going anywhere. It won't "fail" more.

Those look like Mutual Materials Roman Stack Stones. You can see on the short leg that the running bond isn't done well. You have vertical breaks running through two courses. You can easily take that apart and try to have the vertical breaks topped with a full stone so that they don't align so much.

This isn't something to worry too much about.
posted by humboldt32 at 9:36 PM on June 22, 2018 [1 favorite]

Response by poster: Thanks very much everyone for helping me with something I know almost nothing about!

You've answered all my questions and given me background into your reasoning, I couldn't ask for more! So I'm just going to mark each of your main answers as best.

I like that one of the options is to let it go, at least in the short term. I realize, no guarantees in this world. Thanks again for your time and expertise.
posted by forthright at 10:51 AM on June 23, 2018

I would have thought a sledgehammer to be the most difficult possible tool to use for fixing a minor cosmetic issue like that. I'd try sticking the tip of a crowbar (not one of those feeble little one-handed hooky nail pullers, but a serious chunk of steel - what I believe the US calls a digging bar) into the crack between the wall and the concrete path, then just gently leaning on it to make the upper courses of wall stones slide back into place.

Unless there's some ongoing process causing the foundation soil to wash out under the wall, I would expect this to be a permanent fix. And even if it wasn't, it wouldn't be hard to do it again in another seven years.
posted by flabdablet at 11:37 PM on June 23, 2018

Response by poster: Thanks for the additional thoughts, flabdablet! Yes, I am familiar with digging bars from seeing contractors use them, so I can see what you mean (though I didn't think of that).

Perhaps it would make sense to combine your approach with jamjam's idea about combining this project with the lights replacement (i.e., digging the channel or trough just within the wall).
posted by forthright at 6:20 PM on June 25, 2018