retaining walls?

Question

if i am going to build a retaining wall with 3 sides,2 sides @ 4ft by 3ft and one side 22ft by 3ft high, with blocks that you get from lowes measuring 8"longx3"highx5"depth. 45 blocks i believe. how deep will the footer be, and do i need to lay sand and stone first, or can i just pour in a ready mix concrete to lay my wall on. i just don't want my wall to sink when i build it. cheers. here is the blocks i mean http://www.lowes.com/lowes/lkn?action=productDetail&productId=82790-215-5701&lpage=none

Answer 1

A segmented block wall, especially a 3 foot high block wall must be properly based or it will fail.

Remove the soil from under your intended wall first. You should plan on this area to be level when finished digging & 6" wider on either side of the wall material you intend to use(6"+5"+6" = 16" wide). The depth you need to excavate to is a minimum of 9" deep. This allows for 6" of comapacted gravel and at least one course of blocks below grade. Compact the subsoil before you place the gravel in the excavated trench. Use #8 gravel, and compact this gravel after every 2" of gravel is added to the footing area. Add gravel up to 6", compacted. Use a plate compactor with at least a 6000 Lb./Ft. of centrifical force. Lay the first course on the gravel and make certain this course is level. Each subsequent corse should be offset into the hill by 1/2 - 3/4". This offset is called batter. Batter helps to offset the pressure of the soil behind your wall. You should place a drain tile behind the first course of block. You should backfill with gravel for drainage. You should use landscape fabric between the backfilled garvel and soil so the gravel does not fill with silt. Plan on exiting the drain title to the outside of your walls so that water pressure does not build up during a rain storm. Good luck.

Answer 2

You should bury at least one block as a footer. Dont use concrete if you live in an area where it freezes. Frost heave will bust the concrete up and your wall will move. Sand does not compact well enough to keep your wall stable. I recommend using limestone, crushed fines work well. The most important part is to get your footer compacted and level. If you do that the wall part is just grunt work. Good luck.

Answer 3

Dig in the first layer compact the ground as flat as you can. Layer sand mixed with cement and tamp it in.
Set the first brick level all sides
Tamp brick in place
then lay the next brick.
Your footer is one brick thick with compacted dirt behind it
The next layers will have gravel behind it.

Good luck and its always very nice to see something like this you have made

Answer 4

From the dimensions of the block, you'll need 6 blocks per square foot. Your wall dimensions total 90 square feet. You'll need 540 blocks.