CMU retaining wall...

Discussion in 'Hardscaping' started by Grimace, Mar 28, 2009.

  1. Grimace

    Grimace LawnSite Member
    Posts: 21

    I'm building a 2 foot retaining wall of CMU block. Desert location, no frost, very little rain.

    It will be 3 courses of 8x8x16 block on a 12 inch wide by 12 inch deep footer. Rebar every 4 feet in a filled void. So far so good? Do I need to rebar and fill every void?

    Eddie
     
  2. Grimace

    Grimace LawnSite Member
    Posts: 21

    Little help guys please, I could really use a pro's opinion on this. My main concern is the footer. Is 12 inches deep really necessary on a 3 course wall? Can I get away with 6 inches? Concrete is the most expensive cost of the wall for materials and labor. Cutting back on the footer can save me %20 of total cost.

    Eddie
     
  3. MRBsx2

    MRBsx2 LawnSite Member
    Posts: 85

    First off you do not need a 12 inch thick footer, all you need is 8 inches of concrete but you should have rebar out of the footer every 18 or so inches so that you can fill those block cells for strength. Second make the footer at least 18 inches wide 12 inches wide is not enough. I lay block all the time foundations, walls anything masonry if you need any other help just ask.
     
  4. Grimace

    Grimace LawnSite Member
    Posts: 21

    Heck, you just increased my costs...lol 18x8 comes out to 1.125 cubic feet per foot. 12x12 was only 1. Oh well, you got to pay to do it right I guess.

    By your estimation, how much concrete do you think it will take to fill a block void 3 courses high? Should I use concrete or mortar to fill the voids (concrete is cheaper)?

    Do you think I need to worry about drainage? Maybe half inch pvc pipe in between the blocks every 8 feet or so? We get 6 inches of rain per year, our climate very similar to Phoenix.

    Thanks for your help.

    Eddie
     
  5. MRBsx2

    MRBsx2 LawnSite Member
    Posts: 85

    I would deffinetly use concrete to fill the cells make sure you put rebar down to the footer and then fill the cell, As far as drainage i would run a 4 inch drain tile behind the wall surrounded with #57 stone and out to daylight on a wall that small you dont need weep holes. Just my opinion you can do it if you want though not gonna hurt anything.
     
  6. 2low4NH

    2low4NH LawnSite Bronze Member
    from NH
    Posts: 1,891

    drill and pin at a minimum of every three feet pour the cores that are pinned. do not use mortar! mortar is used for joints only. fill the voids with crete. what are your plans for capping the wall?
     
  7. 2low4NH

    2low4NH LawnSite Bronze Member
    from NH
    Posts: 1,891

    and a 12-16 inch footer will work only go 8 inches deep
     

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