Not quite a retaining wall, not quite edging

September 17, 2020 11:54 AM

We live in a split level home, with a yard that slopes up to a front door between the levels. The sidewalk from the driveway to the door is L-shaped and in steps. We had plants in a kind of slope around the edge of that... until my partner got restless and dug it all out into terraced levels... without actually having a plan for how to support the new dirt walls this leaves us with. Please help.

So how do we support the various walls o' dirt this creates? On the shorter ones, we can use plastic edging, sure. But some of these are 12-14 inches high. Picture little rectangles dug out into a slope with a dirt walls on one side, the sidewalk on the other, and a little wall/edge at the end four to six inches higher than the next similar box/terraced area.

Is building a retaining wall really our only choice? Is there something like plastic edging only taller, maybe that could be secured with stakes? This will be behind plants, so cosmetic appeal isn't a big factor.

posted by DirtyOldTown to Home & Garden (6 answers total)

Railway sleepers are the thing people use a lot in the UK. Alternatively, you could build something using treated timber stakes and screw on some lengths of treated decking; the plastic stuff would work even better.
posted by pipeski at 12:05 PM on September 17, 2020

I’ve seen people use pressure-treated boards held in place with rebar sunk into the ground.
posted by outfielder at 12:34 PM on September 17, 2020 [1 favorite]

I'm not sure, but it sounds like your house and front landscaping is similar to mine. So you might want to review the answers to my previous question, even though your situation may be somewhat different (?).
posted by forthright at 12:41 PM on September 17, 2020

You can get a variety of decorative concrete edgers at big-box home & garden stores, ranging from 2-inch wide x 5-inch tall edgers to more hefty cinder block but nicer-looking, which you can install in various terracing configurations.

Here's what one such store offers just as an example (apologies if the link is localized and won't work).
posted by under_petticoat_rule at 12:57 PM on September 17, 2020

You might be disappointed to hear that what you're describing are retaining walls. But, good news! A short retaining wall is relatively easy to build, requiring little skill. A bonus is that you're dealing with less material costs since they're on the smaller side.

My experience here is with several hundred linear feet of wall about three feet high with sloped backfill. In my jurisdiction this was on the very edge of what I was allowed to do unpermitted, and manufacturer guidelines included fiberglass pins between courses, geotextile fabric, and compacting the soil.

I suspect you will not need a permit for walls of that size. I would not recommend some sort of plastic, because in all my DIY years the consistent thing I'd usually change is that I'd get better materials.

You'll find manufacturer brochures online or at places like Home Depot. Don't overlook local places that just sell blocks/bricks and the like because they might have more options. You can also get blocks delivered to you. That's what I did but I was using huge (not super attractive) 110 lb. blocks to save on material costs. You will have more options for smaller blocks (and of course really shouldn't use huge ones at that scale).

A couple of other options I see used in this situation are low brick walls and stuccoed low block walls. These are possible for the motivated DIYer but if you're wishing you could just throw in some plastic thing, I'd advise against it—they require you to work with cement which can be fiddly to learn.

Very roughly, I had to dig for a wall footing (underground portion) a certain percentage of the wall height plus some for gravel drainage, install and level gravel, install and level blocks, and fill in the dirt you moved. I don't know if a low stacked block wall will need gravel footing, and I don't know how frost affects this (I don't get frost).

If you spend the time on prep/layout (level is important) it goes together pretty easily and lasts forever; you'll never have to touch it again. Just get the fancier looking styles, please, or else you'll be stuck with boring, drab grey concrete like me!

I am less familiar with products for edging between different areas on the same grade. I would think that plastic might be an acceptable choice there, particularly if the border is curved. But that's an easier product to choose and install, I think.
posted by RikiTikiTavi at 1:03 PM on September 17, 2020 [1 favorite]

I have made low simple walls using; tree trunks (pinned into place with 12mmØ rebar via a hole drilled thru trunk) - the effect can be soft and organic; old timber power poles (same pinning method), and also old concrete fence-posts and concrete power poles. This approach often incorporates steps into the 'structure'.

Treated timber is often too durable (century+); with time plants will grow into the wood and the whole slope becomes a unity locked together with roots.

With care you shouldn't get too much soil leakage between the gaps and the plants will solve that anyway.

With posts and poles it is best that they are durable timber and not arsenic-treated but you're probably okay in the US. Durable trees not needing treatment includes Osage orange which may be in your area.

I have used a geotextile web system e.g. Geoweb and pinned it to slopes with rebar - cheaper than fibreglass pins. But that is when the slope is bare and the webs cells are then filled with soil. It works well but can be hard to find in small quantities.
posted by unearthed at 4:33 PM on September 17, 2020