Nuances of a cinder block retaining wall

[chibiabos]

Building a cinder block retaining wall, three feet high, 24 feet long. Been a while since I did any masonry but I remember the basics and helped my neighbor build his a few months ago. In fact, this wall will tie off an end of one of his runs. Block is 8x8x16 plain cinder, will be filled solid and have a stucco skimcoat. Wall will hold back a 2.5 foot wide strip of sandy soil between a sidewalk and my neighbor's block wall. Has good drainage.

My question regards the footing. I'm on the California coast, so there's no freezing; no frost line to consider. Below-grade soil is hard, virgin rotted sandstone. The footing will be concrete, 12" wide,

8" thick, buried 6" or so below grade.

What number of pieces of 1/2" rebar is recommended for this type of footing under this kind of wall? Is two enough? I plan to bend one or more pieces of rebar up at 90 degree angles along every four to six feet of the wall to a height of 30" or so, and slide blocks down over them, then fill and cap all blocks with solid concrete, plus generous placement of masonry ties during construction.

Any useful thoughts and advice is highly appreciated.

-chib

[Steve]

You don't mention where you are in Calif. but I have had several homes on San Diego and San Diego Co. and any wall 3 ft or taller requires a building permit..

Normally I wouldn't even mention this since I do a lot without a permit.. However I do know there is a reason for a permit and proper building plans and inspection of division and retaining walls..

A improperly built wall can be very dangerous.. I happen to know of some children who were crushed when a wall collapsed on to them.. All they were doing was, a kid thing, swinging on a gate..

Your masonary retaining wall requires better planning and engineering than you are going to find in a news group..

Sorry

Steve

[chibiabos]

Thanks, Steve. I'm in Santa Barbara County, outside any city limits. I checked. Structures under 4 feet high don't need permits.

I was merely asking the folks here if there were any major flaws in my plan.

I've looked through most of my home improvement books, and online as well. They all agree that my footing is adequate for a wall like this but none of them mention rebar, size, number of bars, etc. For all I know, rebar isn't necessary. I plan to use it, anyway.

-chib

[DanG]

You have not had much response to your question. Engineering will help prevent roll over. If you are going to do your own anyway, I would suggest that you make the footing wider. A typical minimum would be twice the wall thickness, as a retainer, it could easily need more. It would be usual to keep more of the footing under the hill. Drainage is critical as hydrostatic pressure behind the wall will push it over Residential footings require 2 #5 bars. I would think you need a tied mat with your hook bars coming up in the block cells. I would suggest 4' o.c. as an absolute minimum.