First Retaining Wall need advice

Discussion in 'Hardscaping' started by Youngbeginner, May 1, 2007.

  1. Youngbeginner

    Youngbeginner LawnSite Member
    Posts: 76

    How would you build this wall. Materials, procedure:


    Retaining wall around pool that is down on basement level. 8'x40'

    Southern Indiana limestone and red clay soil

    New house ($600,000) with vinyl siding and red brick with some limestone trim

    Thanks,

    Landon
     
  2. Dirty Water

    Dirty Water LawnSite Fanatic
    Posts: 6,799

    Yeah, I wouldn't be building any 8' pool load bearing walls as a first job.
     
  3. Youngbeginner

    Youngbeginner LawnSite Member
    Posts: 76

    Sorry, I wasn't clear, the wall's base will be level with the pool, then goes up.

    __
    ::|
    ::| Wall
    ::|
    ::|
    ::|_____________________________
    ::::::::::::::::::\____Pool_____ /:::::::\
    :::::::::::::::::::::::::::::::::::::::::::::::\______________
    :::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::
     
  4. chris638

    chris638 LawnSite Member
    Posts: 149

    If the overall height is 8', don't mess with it. Start with 3'.
     
  5. Youngbeginner

    Youngbeginner LawnSite Member
    Posts: 76

    Honestly this is hypothetical worst case scenerio on a job someone called about today. I am confident in myself, but I will not take on a job that I feel will turn out unsafe because of my lack of knowledge or skill. I have built smaller walls up to 4 feet tall before, but I would like to know how the taller walls differ ex. backfill, drainage, base prep, etc.

    Thank you,

    Landon
     
  6. chris638

    chris638 LawnSite Member
    Posts: 149

    Anything over 6' tall in OH has to be engineered, including stamped blue prints. Over 6', you can't use bi-directional geogrid, base needs to be pressure tested, especially if you are into red clay. You are looking at a minimum of 5-6' of geogrid behind the wall. Inexperience on your part could lead to inproper installation of block and failure. Another effect from inexperience could be losing your shirt on a job like this. If you don't figure the proper cost of geogrid, gravel backfill, excavation (around 18" deep), and drainage you can easily end up installing that wall for free.
     
  7. Youngbeginner

    Youngbeginner LawnSite Member
    Posts: 76

    chris638-

    Thank you for answering fully, I understand your skepticism now.
     
  8. ChampionLS

    ChampionLS LawnSite Bronze Member
    Posts: 1,066

    It's not that big of a deal. It isn't even scary. Regardless of the wall, most of the engineering is based upon costs associated with the wall. I. E. in the worst case scenario, you'll need several layers of geogrid, and trucked-in infill soils. Here in NJ, almost all of central NJ is red shale clay. On an average, we excavate for a 6" leveling pad made from 2a modified (QP etc.) The base course is laid and the cores are filled, along with behind, and in front using the same 2a. A drain pipe is laid behind the first course, and back filled with 2b (clean stone). No filter fabric is used between the drainage aggregate and infill soils. -Some manufacturers call for it, but as per all the training classes I've been to, they are now omitting it. Depending on how tall of a wall your building, and whats at the final grade, that will determine your geogrid length and at what intervals it's installed at. On a heavy retaining application, it can be at every other course, and usually 4-5' back. We use Bank-run gravel as the infill soil, because of it's high compaction ratio,and ability to drain. Using Geogrid is nothing.. it's not hard and it's not scary. Only takes minutes to layout. It's the preparation of the infill soils that take time.

    Whatever block you intend to use will determine the geogrid type and length for your wall. You will need an engineer to sign off on your design, but thats still no big deal. Usually just a time consuming inconvenience.
     
  9. Youngbeginner

    Youngbeginner LawnSite Member
    Posts: 76

    ChampionLS-

    Thank you very much for explaining the process. I want to learn exactly how to build the wall safely. I knew that it was not a complicated process, but one that did require preciseness and quality workmanship.

    Thanks,

    Landon
     
  10. D Felix

    D Felix LawnSite Bronze Member
    Posts: 1,898

    If Lawrence County is anything like Putnam, the county will probably laugh at you if you inquire about engineering and/or permits...

    You're in school for LA, do you even know what photosynthesis is? Let alone how to build a wall?? :D :D :D I'm kidding, of course, but I did hear Dr. Dana ask an LA student many years ago if they knew what photosynthesis was... But I'm getting off subject here....

    Anyway, no, the wall probably won't be a big deal if you've got reasonable to decent access. For SRW work, I personally prefer Versa-lok products to all the other manufacturers we have here. If you want a contact name, PM me and I'll be happy to pass along info to you. The person I am talking about used to rep for Irvin's before they quit selling directly to hardscapers, so he knows the product...

    I believe our equivalent of Champion's 2a is 53's or 73's- we've been using 73's if/when we can.

    HTH.
     

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