Retaining wall base

Discussion in 'Hardscaping' started by cbass139, Mar 18, 2013.

  1. cbass139

    cbass139 LawnSite Member
    Messages: 51

    2a modified*

    OUTLANDER LawnSite Senior Member
    Messages: 576

    never clean for your base. Only clean gravel for your drain field (backfill) dont want erosion qualities under your wall, or (base) what holds the wall. Clean has no compaction, and has voids....I've heard of some using fabric and all, but still its just not right. You dont want drainage under your wall, only behind it (controlled drainage)....#57 crusher is very good base
  3. cbass139

    cbass139 LawnSite Member
    Messages: 51

    That's what I thought.. Do some research.. It's acceptable????:dizzy: but why?? I'm totally on board with you in the thought process but I can't see how the other way is ok! I preached the same and decided to look it up and was really thrown off!!

    OUTLANDER LawnSite Senior Member
    Messages: 576

    I know what you're saying....i just look at these opinions sometime like, why do what can work instead of what does work?..:laugh:
  5. cbass139

    cbass139 LawnSite Member
    Messages: 51

    I hear ya what are ncma specs
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  6. clipfert

    clipfert LawnSite Member
    Messages: 205

    NCMA specs are minimum 6" depth for base and 6" wider than your base course front and back or 12" wider than your block.
    We always use a 24" wide base regardless to accomodate plate compactor.

    If your asking what NCMA is...National Concrete Masonry Association
    Its like ICPI but for SRW's
  7. cbass139

    cbass139 LawnSite Member
    Messages: 51

    I'm curious as to the ncma aggregate specifications for the base of a gravity srw.
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  8. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Messages: 6,623


    Not sure where you obtained your knowledge, but what you wrote - AIN'T correct.

    Number 1: Clean aggregate (#57) self compacts.

    Number 2: It is PERFECTLY acceptable to use. Infact, if you look at most engineers specs you will see where they list for the base that you can use: a) Concrete. B) crusher run. C) #57. All 3 are acceptable.

    Also - think of a french drain (dry well). A french drain consists of #57!!!! Because IT DRAINS!!!

    So, if you think about it, you do not want water standing at the base of the wall. With that said - #57 clean is perfect because water can drain through it.

    Ok, so there is probably someone reading this thinking "why would water collect at the base of the wall, what is this idiot DVS talking about?" Well - I have a buddy in Hinkley Ohio whom had a wall built by a decent size, busy, well known contractor. And that large, well known contractor turned out to be a contractor from He!!. And he built the wall with water collecting at the base. He used crusher run for the base and directed water to collect behind the wall! Had they at least used 3/4" clean - then maybe, just maybe, the water could drain.

    Sometimes we use clean. Sometimes we use crusher run. Both are 110% acceptable. And we been building walls since 1997.

    Last edited: Mar 19, 2013
  9. cbass139

    cbass139 LawnSite Member
    Messages: 51

    I value your opinion I have read a lot of your posts... What do you use to determine which stone to use... I can not understand the concept and in order to sustain a good reputation I should. I understand using a crusher run base and drainage to redirect collecting water but would you pitch your subgrade to drain away and then install #57 creating a large French drain under the wall? Is using #57 stone preferred for smaller walls where drainage is not a huge necessity for added protection. Is #57 stone base used in conjunction with drainage behind wall... So many questions! I feel like a noob agian! Someone help me with this concept! I know a lot of others viewing are in the same boat as me.. I'm not afraid to say Im clueless to this concept of #57 as an srw base. Their has to be some methodology behind it.. Heads ... Tails... #57...cr8.... Just doesn't cut it for me haha
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  10. scagrider22

    scagrider22 LawnSite Bronze Member
    Messages: 1,272

    DVS, do you know the name of the company that built your buddies wall, it didn't happen to be Exterior land development? I live in the next town south of Hinkley.

    As for #57 I agree with DVS. Most city engineers require us to use #57 for our base on walls and they do compaction testing after every lift on a city job. We always get above 97%
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