Cinder block

bigalpha

Moderator
Location
Tucson, AZ
If I have any luck at all, I might be able to pick up a bunch of free cinder block. Since it's not nearly enough to build a shop with, I was thinking of using it to build the columns to a carport in the backyard and use them to create a border for the gravel driveway in back as well.

Using cinder block for the columns shouldn't be a problem, right?
 
as long as you use rebar to reinforce it and backfill with concrete, it should be fine

Think it'd be strong enough if I just stacked two side-by-side and went up with just two? I would rotate them so they'd be "staggered".

Check your local building code. I'm sure there is a ruling about the footers for the columns.

And make sure there's no permit process
 
Think it'd be strong enough if I just stacked two side-by-side and went up with just two? I would rotate them so they'd be "staggered".
Yes. Cinder block can have a compression strength "as low as" 1250psi according to my sources, figure an 8x16 block with a 1 inch wall around the edge and a 1 inch web across the center, that's 50 square inches of material per block so approximately 31 tons of load per block - the roof isn't gonna weigh more than a few tons even with a full snow load. That's assuming you properly mortar between them so there aren't any high stress contact points with the rest separated by air. As xjtrailrider said, make sure you are good on the footings.
 
Your going to have to dig a footing below grade and it has to be below the frost line not sure what that is over by you but here in NC its about 9 inches down. The footing is going to have to have rebar in it which runs up almost the full height of the columns, the columns do have to be solid filled with concrete. Your footing has to be at least 3 inches below finish grade here in NC and the footing has to be at least 9 inches wider then your column on all sides. The depth of the footing is probably going to have to be at least 1 foot 3 inches. I would say you at least want to have (3) #4 Rebar running both ways in the footing. As for the Rebar that runs up the full height of the column that is probably going to have to be a #4 rebar also. Make sure that whatever wood touches the CMU's is pressure treated that's standard code everywhere. So you could simply just run a plate along the top of the column and then place a beam on top of it. The Plate is going to have to be bolted down to the column. I would place the anchor bolts in before the concrete in the CMU's has cured.

If you have anymore questions on that let me know. I'm an Architectural Designer.
 
Wow, thanks! That's pretty good info. The cinder block isn't for sure yet so I'm just getting a feel for things.
 
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