I'm looking to build a retaining wall on my sloped backyard. I'll be using cinder blocks (with mortar to join them together and rebar for added stability).
(added info: at the lowest point the wall is going to be close to 4 feet tall, not counting how deep I have to dig and how much of the wall needs to be underground)
Some questions:
1) Footing or no footing? Can I start setting the cinder blocks directly on base gravel, with rebar vertically every 3-4 feet for added stability, and filling them up with mortar as I go? Or do I need footing?
2) If I need a footing, how deep into the ground should my footing be? Not how deep the footing itself should be (I'm thinking I'll go with a 1' footing—feel free to comment on that), but rather how deep into the ground do I need to dig my trench in order to set the footing?
I know that for gravity walls on sloped yards I need to measure 5' out of where I plan my wall to be and dig the difference. What about for cinder block walls, is it the same? Or the added strength and stability of rebar+mortar, or footing+rebar+mortar, makes it so I don't have to dig as much?
Hope the info I provided is sufficient to get help and answers from. Let me know if you need me to try and sketch the design of the wall for added context.
Thanks
Best Answer
Can I convince you to not do this ?
Honestly not trying to be an ass.
Please, please - Get a quote from a company that builds retaining walls.
The quote will cost very little or nothing.
You will be shocked at the cost, and not in a good way.
The quantity of material needed to build the wall, will amaze you.
Please get a quote or two first.
I promise you, you will not regret it.
Block walls work in compression, heavy things directly on top of them is fine.
Side to side, their goal in life is to tip over, and they are damn good at it.
Blocks work because they are tied to very solid, heavy things at the top and bottom that run the length of the wall, and have regular supports at a right angle to the length of the brick.
A 1' deep pile of soil, behind a 4' block wall, 1 block long, weighs 500 pounds.
The path of least resistance is to knock over the wall.
Blocks, attached with mortar, to the soil behind the wall about as strong as a 2x10 resting on its edge.
The question is more one of how many yards of concrete will you need to build the footing.