I have a ton of brush that I used to burn, but I recently bought a chipper/shredder and want a spot to compost it along with grass clippings and greens. I also have 3 tons of CMUs that are just sitting here, removed from an ugly garden fence.

I want to make a 3 walled container for the compost, sort of like you'd see at a gravel yard. The back wall the tallest, and the other sides slanted down. I'll likely push the compost against the back wall, then when I mix up the compost, I'll just rake it flat and shovel it back into the back.

What's the laziest way I can build this with what I already have so that it doesn't fall over in 5 years or develop other issues?

I was thinking I want to do a 10 inch gravel footing and dry stack the CMUs. Maybe I'll fill a few with concrete, but that would require mixing concrete - maybe I'd rather fill them with really coarse gravel. I'll likely cut some of the CMU's diagonally with a diamond grinder so I can get a nice straight taper down and cover the CMUs with some cap blocks.

I don't know about mortar, because the CMUs are dirty. I don't know if it'll stick, and I don't know about how long it would take to clean them. I suppose kissing them with a grinding wheel would do the trick if it comes down to it, but I don't really feel like learning how to mortar anything either.

  • CMU = Breeze Block/Cinder Block. Sep 28, 2014 at 17:38
  • You could make double-thick walls, and alternate each row between blocks parallel to the wall and blocks perpendicular to the wall.
    – mbeckish
    Sep 29, 2014 at 20:29
  • 3
    How tall do you want to make the wall in the back (ie, how many blocks total)?
    – J. Musser
    Sep 30, 2014 at 16:55
  • @jmusser about 8 bricks tall, which is about 5ft. I have a total of about 140 blocks to use, but they're cheap enough. Considering doing double wide and perpendicular
    – kavisiegel
    Sep 30, 2014 at 17:38

4 Answers 4


Dry stacking and filling with rebar and concrete sounds like a great idea. Pretty easy and brainless.

  • What about filling with coarse gravel? My brain tells me that should prevent blocks from sliding around
    – kavisiegel
    Sep 29, 2014 at 12:33
  • 3
    I don't think so. Concrete in the cores won't permit the blocks to slide around; coarse gravel will, as it's not a solid mass.
    – iLikeDirt
    Sep 29, 2014 at 13:24

How about dry stacking them and using 4x4s inserted inside and buried in the ground

  • 1
    the 4x4 rot out, 3 tons of bricks falls over on someone. Also, not sure if a 4x4 will fit.
    – diceless
    Sep 29, 2014 at 19:30
  • not if you use cedar or redwood or treated lumber.
    – sww1235
    Sep 29, 2014 at 19:35
  • 6
    Even rot-resistant woods will rot eventually; it just takes longer. (I need to replace many of the cedar posts holding my fence up.)
    – keshlam
    Sep 29, 2014 at 21:10

I just bought this. It is cheap and aesthetic:


  • There are a number of good and affordable variants, but it sounds like kavisiegel's eager to find a use for the CMUs... and the "shovel and toss" approach to stirring the compost heap is an interesting idea. (My solution on the main heap has been that each fall I turn it upside down, distribute the stuff that's fully "cooked", then add the year-end lawn clippings and leaf shreddings until it's full and I have to feed the town's compost system instead. Seems to work well enough...)
    – keshlam
    Oct 1, 2014 at 20:31

I ended up doing an 8" footing of crusher run gravel, tamping it in 3" layers and then getting a few new solid blocks to run perpendicular to the recycled blocks for stability. This ends up being a "floating" structure.

Test Fit: Test fit

Gravel: Gravel

Stacking: Stacking

Done: Done

  • 4
    Nice build! Three separately compacted lifts of crusher run gravel for a footing? I see some missed opportunities for laziness... You and I should never team up on a "simple" project. Your lazy compost box would have flood lights by now.
    – mac
    Oct 8, 2014 at 20:53
  • @kavisiegel How has this project been working out? Any updates? Aug 31, 2015 at 14:55
  • @BrownRedHawk It has been working out very very well. I'm glad I did it this way. No settling so far. I tapped it with a tractor the other day and took 3 minutes to fix it. The open dirt on the ground is great, earth worms have found their way through which is the best compliment mother nature could give my compost pile. That being said, I'm likely to add a second and third bay next spring. Not sure if I'm going to mimic this style of construction though. Rather expensive since I'm out of bricks.
    – kavisiegel
    Sep 6, 2015 at 3:57

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