How To Build A Retaining Wall That’s Flexible

I made lots of mistakes in planning the basement for my Greenhouse, and one of the first that I recognized was that I didn’t contract for the retaining wall. My concrete guy was so nice and accommodating and had already happily changed my door locations the night before the walls went up. I couldn’t bear to ask his help for this too.

I’d put a concrete pad in with a contractor friend and knew that this far North you have to dig at least 36″ deep to get below the frost line. The footings will actually heave out of the ground as the ground freezes and thaws if you don’t. However, I watched the entire process of basement construction, and they didn’t put footings in that deep during construction. Perhaps because the footings are nearly 8′ under the ground in almost all areas the few exposed areas are protected? I went with that theory and dug a modest hole for the footing to the west of the small concrete patio/pad.

I framed it out with some scrape 2×3, couple of screws and left-over wood stakes. The fall rains kept causing me problems and I had to use other left-over lumber to create a sort of ‘tiering’ on the slope to hold back the clay. Those same rains made it impossible for me to drive my mini-van back to this area (no truck at this point). When I researched my van’s hauling weight limit 400 pounds was the lucky number, so I never hauled more than 8 bags of Quick-Crete at a time over the rear axel. It was a brand-new van and on rainy days I would park at the highway and carry each bag to the construction site.

A make-shift water-catchment experiment saved me from having to haul in very much water to mix in with the Quick Crete.

Everything was mixed in a wheel barrow with a hoe and shoveled right into the hole. I finished the surface with a trowel I had gotten at a garage sale and broken broom head.

The idea was to install the this footing and extended ‘patio’ at about 1/4″ to 1/2″ lower than the original. This would allow water to drain from the professional patio so it would be less likely to get trapped and freeze or seep under the basement door. It also created a little lip that served to hold the cement blocks for the retaining wall in place.

There might be a day when a staircase is built on this North side of the Greenhouse. Maybe someday a goat shed will be added as a lean-to. I don’t know for sure, so dry-stacked cement blocks were chosen for this experiment.

Cement blocks now come in two shapes plus the ‘cap’ blocks that sit on top to finish it off. The regular block has concave ends on both sides. There is now a ‘end block’ that has a smooth end on one side and the other end is smooth with one channel. I haven’t messed with cement blocks in decades, so I don’t know when this became a thing, but it is a very nice cosmetic element when you are using them the way I am.

I had originally planned to use my retaining wall as a sort of staircase and it worked well in that way before I had built the stair case inside. However, after breaking my leg the summer of 2020 that idea is dead to me. Now the plan is build up the wall high enough that I can barely see over it. As the rain washes clay down onto the patio I can scrape it off with a flat-edge spade and toss it back up into the corner of the basement and cinder blocks. Continuing to back-fill so the earth can protect the basement from the winter cold.

My only block-wall experience was with the kid’s Legos, so all I knew was to the wall was to crisscross the cement blocks. My youngest recognized the pattern and said that’s what he does in Minecraft! This plan uses twice the cinder blocks you would normally need, but that made perfect sense when the wall would be used as a ‘staircase’. Now that I’ve decided that’s too dangerous, I appreciate that such a thick wall is not going to be pushed over easily. The blocks are less than $2 each, so it’s worth the ‘extra money’ to not have the wall tip over, and you buy yourself options when you have extra building supplies on hand.

As you can see here, the roof drip-line is 14 feet above the basement. The rain falls with such force that is has cut a straight channel in the heavy clay and the amount of water has built up and pushes the cement blocks in just this one year. All new blocks are added 1/4” in from the block below, but it won’t be long before I’ll have to remove the whole wall, dig some of the clay out and restack it again.

Overall, this setup works for the Greenhouse because it is flexible. We can restack the configuration if we decide to put a staircase or ‘deck’ of some sort on this side. We also could enclose this side and remove all this dirt and re-use the blocks. There are a ton of options!

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