First Course Blues

Discussion in 'Hardscaping' started by White Gardens, Jul 24, 2011.

  1. White Gardens

    White Gardens LawnSite Fanatic
    Messages: 6,776

    So what's the best way to set the first course of a retaining wall.

    I do it the way I was taught, which is to get your compacted fill as close to level as possible, then use fill sand to set the first course and tweak when needed.

    I end up using as little of sand as possible, but struggle along sometimes where my base might be a little off.

    So, my thought is to come up with some sort of screet rail that's 1/4" or smaller to screet off the sand to get a more consistent base to speed up the first course. The only problem is that I wonder if too much sand will settle and throw the wall off over time.

    The problem I see with a small screet rail is it getting tweeked or bent over time and then not really helping me out.

    I've only done a handful of walls where they are only a couple of 2-3 courses and caps. I can see that doing any larger walls where I'm going up 4 courses or more can create problems if the first course is not quit 100%, thus leaving the caps with slight imperfections when butting them up.

    Any thoughts?

  2. STL Ponds and Waterfalls

    STL Ponds and Waterfalls LawnSite Bronze Member
    Messages: 1,174

    As long as your an inch or under you'll be fine. Get you base to spec and if you start to see more base being needed to level off add some more and compact. If you have to and it's possible run a stringline to see your low spots and adjust your base where needed. I know NCMA specs sand for a base but I prefer to just use 1" minus or whatever your base material is called.

    A lot of times your block can be off spec by a 1/8" or so and that maybe why they don't totally line up for your caps. Pennies and a cup grinder can be usefull in shimming your block if they are really out of spec.
  3. White Gardens

    White Gardens LawnSite Fanatic
    Messages: 6,776


    Basically from your post I'm probably just splitting hairs too much when installing walls and that's what's throwing me off. Most of the time I use string lines for all my projects as I haven't done enough hardscape work to warrant buying a lazer yet. I usually have 5 line levels with me and use the two or three that give me the same consistent bubble reading.

    Good call on the pennies and thanks for that tid-bit of info, I like that idea as sometimes I can be off by just a fraction, but then makes my caps look off to the trained eye. I just got done with a very short wall where the center had an engraving on the cap. I had to do some very minor tweaking so that the letters that crossed the seams of the cap had to line up perfectly.

    For screet rails, I'm thinking of going to a steel shop and see if they have any square or round rod at 1/4" or so to use for rigidity. Then ultimately store them in a section of PVC pipe or similar to make sure they stay true during transport and storage. I hate the idea of using conduit for rails and having them get tweaked real easily.


  4. SVA_Concrete

    SVA_Concrete LawnSite Senior Member
    Messages: 467

    i would like to learn more about this Screet thing and the lazers
  5. STL Ponds and Waterfalls

    STL Ponds and Waterfalls LawnSite Bronze Member
    Messages: 1,174

    WG, so you don't get your balls busted any harder it's "Screed" and "Laser". :)
  6. Stillwater

    Stillwater LawnSite Platinum Member
    Messages: 4,889

    For block walls I have 3 ways, Time, more time, and a little more time. Frustrating as it may be for me I accept the fact that this will take time. I do not look for any short cuts on first course. I accept nothing but dead on level. No creative shimming, no creative screening, no looks good from my house crap, or it's good enough. just time and crusher run or what ever I am using for a base. Time is paid back to me later in the install when I can fly through it. When I pull out and warranty begins the last thing I want to be thinking about is the creative shimmimg or sand that may or may not move because when it does move (my personal opinion it will) So the politically driven money grubbing NCMA can shove their arbitrary ever changeing on a whim specs up their *** Its not their money that will pay my labor bill during a service call it's mine. I sell labor, and time is what I sell...
  7. White Gardens

    White Gardens LawnSite Fanatic
    Messages: 6,776


    Nice catch. The boy has been up since 4am and my mind isn't working correctly.

    Maybe I was also was thinking of the cheap 40's I used to drink back in the day. I think it was spelled with a z.

    Last edited: Jul 24, 2011
  8. White Gardens

    White Gardens LawnSite Fanatic
    Messages: 6,776

    Agreed Stillwater.

    I just want to do it right and make sure the wall stays level after installation. But at the same time, I'm trying to take a little of the frustration out of it.

    The thing I hate is when you think you've done it right and you get off by an 1/16th of an inch or less on the caps. Even though it's close, I want them to line up perfectly.

  9. scagrider22

    scagrider22 LawnSite Bronze Member
    Messages: 1,272

    The easiest way for me to put base down is with a rotater, I have a guy walk in front of me checking the grade about every 1-2' and I correct it with a rake until it beeps level (I only do this on the final lift), then I run the plate compactor over it to smooth it out. I do not use any sand and my first coarse of block goes down pretty fast.
  10. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Messages: 6,567

    One inch of sand is too much. We barely use 1/4" max.
    Posted via Mobile Device

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