cinder block foundation

for those who have cinder blocks SFG beds, do you need a foundation pad or is it just place on a level ground to the desire height. I would like to place it 4 row high due to using 8" of mulch to stuff out the grass.

Hi has55. When I made my cinder block bed I dug down (made a rectangular trench) about 6 inches deep and about 4 inches wider than the block in the area the blocks were going and made sure that area was level all around. I threw the dirt into the middle for back fill later. I used a hand tamper to help level and compact the trench. Since I am in New England I was thinking about movement from frost, but didn't want to spend the money for lots of blocks or the energy to dig down below the frost line. Put in two layers of dry set cinder block, alternating the second row to cover the joints in the first row, and back filled the outside to ground level. Worked out nicely.  No foundation and No mortar was needed, plus if I want to take it apart and move it I can. They do move a tiny bit from frost but settle right back into place in the spring. I'm very happy with how it turned out, using it for the fourth year now. Good luck with the project 

We ditched our cinder block for bricks, because the constant bruised and scraped knees from brushing up against the blocks were too much.

If you are not a klutz, then you don't have to worry about it.  However, if you are like me, then you are going to have similar issues.  I guess you can wear knee pads or find something to put on the top of the blocks to protect yourself.

When doing any kind of concrete/concrete product work, a proper foundation is the key to your project's longevity. For a garden box, you can get by without a footer , but it will last longer with one. Start the first course the way lyndeeloo described.

At 4 courses high, however, I'd be concerned about bulging walls due to the horizontal force of wet MM or other growing medium. I'd definitely use re-bar to hold it all together.

thanks everyone. I see the foundation is the key. I found this link last night.
How to Build a Retaining Wall With Concrete Blocks for a Planting Bed

does anyone have pictures of walls 3-4 level high?

Razed Bed-do you have pictures of your brick bed. how high is it?

I built these for my wife over 20 years ago.  The box on the right is 8x16.  It took a dump truck load of topsoil to fill the box!  The wall on the left is a dividing wall for a garden/sitting space.  The far side is 4 courses high.

The footer is showing because the ground was as hard as concrete, and I decided the heck with digging a trench with a pick and shovel!  

Boffer it's beautiful. is that decorative brick or cinderblock? are the joint cemented or just stack?

Thanks. Around here, we call them 'split-face CMU'. You can google that term. They're cinder blocks with a rough face, and come in various colors.

I mortared the blocks in. But I've seen houses built with dry-set. Here's one way to do it.
http://www.quikrete.com/athome/Video-Dry-Stack-Wall.asp

thank you.

Boffer,

Great video!

However, I do have a question.  With a concrete footer for a raised bed, how does drainage occur?

Thanks!

Since the existing soil was so compacted, I wondered about that, too.  This is what I did:




The perforated pipe and drain rock go all the way around the box on the inside.  I cut a hole in a block on the back side (least visible) of the box for the 4 inch ABS drain pipe to go through.

Clever, Boffer!

I've built one, going on two, berry beds with concrete pavers as bases.  Since there are small spaces between each one, drainage occurs.  My blackberries are trying to go wild!

Good thing I have a "footing" for them, too; a wave of rodents has arrived, and my cats can't quite keep up with it.  Also, I don't want the berry plants to do much spreading.

thanks Boffer for sharing more details.

Boffer, I needed to revisited your comment about your footer. If I understand correctly, you just put a footer above the ground, not beneath it. I was wondering if this would work for me, since I going to put 8 inches of mulch around the base for my walkway. This would save a least one row of cinder block and cut my cost down. At least , that's what I'm thinking. Then I can go up 3 level, instead of four. The footer would be hidden. Question, why do they suggest the footer be in the ground? Yours is working fine.
When you mentioned using rebar with the cinder block, how is that done? forgive my ignorance, I'm not an carpenter or work with bricks, so I need help visualizing it. 

donnainzone10-you used pavers. How high did you go? How long has it been since you created it? Any problems? I have about 500 4 inch wide by 2 inch thick pavers just stack in a pile. Haven't figured out what to do with them. 

If one were building a footer for a structure, there are two factors to consider.  One is to get below the frost line to prevent heaving, the other is to attain a surface of suitable compaction strength. (the usual minimum is 2500psi)  Ex.: If you were going to build a garage on your gravel driveway that's been used for years, the native soil is already compacted from years of bearing the weight of cars and the settling effect of rain, and there wouldn't be a problem.  On the other hand, if you decided to build your garage atop the last owner's row garden, odds are that the top layer that has been rototilled won't meet compaction tests, and you would have to dig down to undisturbed dirt to place your footer.

A garden wall like we're talking about doesn't have to meet any codes, and the weight involved is negligible.  We don't have frost heave here, and my ground was compacted, so functionally, putting the footer on top of ground isn't an issue.  That said, I stub my toe frequently on the footer, and take a lot of ribbing from friends in the trades for being lazy!  

Regarding re-bar:  I've never regretted over-building a one-off project, as the extra time and/or money is negligible in the long run.   But building something that fails and has to be re-built is a sure way to keep me miserable for a long time.  When I was planning my garden box, I couldn't find a reliable source (pre-internet) that could tell me positively whether or not re-bar was needed in the blocks, so I put it in to be safe.  (steel was a lot cheaper then)

I grouted in a vertical piece of re-bar every 16", and a horizontal re-bar on the top of the top course.  That way, I was confident that the wall was built like a Chevy pickup¹.  There's different ways to put in the re-bar; google 're-bar in CMU walls'.  Holler if you have questions.



[1]  Chevy's jingle: 'Solid as a rock'.  

Thank you. Stubbing your toe got my attention. "ouch" I'll look up the info on rebar and get back with you if I have anymore question.

boffer wrote:If one were building a footer for a structure, there are two factors to consider.  One is to get below the frost line to prevent heaving, the other is to attain a surface of suitable compaction strength. (the usual minimum is 2500psi)  Ex.: If you were going to build a garage on your gravel driveway that's been used for years, the native soil is already compacted from years of bearing the weight of cars and the settling effect of rain, and there wouldn't be a problem.  On the other hand, if you decided to build your garage atop the last owner's row garden, odds are that the top layer that has been rototilled won't meet compaction tests, and you would have to dig down to undisturbed dirt to place your footer.

A garden wall like we're talking about doesn't have to meet any codes, and the weight involved is negligible.  We don't have frost heave here, and my ground was compacted, so functionally, putting the footer on top of ground isn't an issue.  That said, I stub my toe frequently on the footer, and take a lot of ribbing from friends in the trades for being lazy!  

Regarding re-bar:  I've never regretted over-building a one-off project, as the extra time and/or money is negligible in the long run.   But building something that fails and has to be re-built is a sure way to keep me miserable for a long time.  When I was planning my garden box, I couldn't find a reliable source (pre-internet) that could tell me positively whether or not re-bar was needed in the blocks, so I put it in to be safe.  (steel was a lot cheaper then)

I grouted in a vertical piece of re-bar every 16", and a horizontal re-bar on the top of the top course.  That way, I was confident that the wall was built like a Chevy pickup¹.  There's different ways to put in the re-bar; google 're-bar in CMU walls'.  Holler if you have questions.



[1]  Chevy's jingle: 'Solid as a rock'.  

Your building methods are superb and I agree 100%. do it right first and one will never regret it.