Cinder/concrete blocks for raised beds, concerned?

To connect the top wood layer, I just tapped some smaller wood pieces into the cinder block voids (every other void) and then applied deck screws. This mass-production is best done with a power saw (skill, table, etc.); not all voids are the same size and care must be taken to use only snug-fitting wood. Cinder blocks are actually quite fragile and hammering tight-fitting wood pieces into them will crack the block. After 10 years I replaced the void wood pieces with hybrid (plastic) wood scraps. Some of the original pieces had shrunk and fit the voids too loosely.


Thanks so much for posting that picture, I was thinking you had done it differently.

Now if I could get some corrugated galvanized steel siding runny horizontal and the top edge goes into a routed groove in the wood, that would look good.

Do you mean adding the metal on the outside of the structure, in addition to using the void wood inserts and top planking? This would require the planking to overlap the cinder blocks considerably and might require using 4-inch blocks rather than the 6-inch blocks pictured above, unless you use 2x10 planks. It would be easier to attach via nails or screws the metal to the edges of the planks. To avoid exposing the sharp edge of the metal, create a recess in the plank edges via power saw. I would be concerned about the metal getting hot.

I also built a 8-foot tall trellis system atop the raised bed and the planking allowed for walking and even ladder placement without disturbing the blocks.

Aren’t those 2x6 you used? If so it looks like there’s enough room underneath for the corrugated to fit. Just as long as the corrugated is cut at the closest point to the blocks. If it’s only a 1/4" overhang or less, then I might have a problem.

As a matter of fact, what’s a day without problems? That would be boring.

My blocks are ~6 inches thick and the top wood is 2x8 (~ 7.5 inches). I have an outside wood overlap of the blocks of 1.25 inches; you could increase this to over 1.5 inches by just putting all the overlap on the outside of the blocks and leave the inside flush.