Raised patio question.

Discussion in 'Hardscaping' started by Redbear, Oct 15, 2005.

  1. Redbear

    Redbear LawnSite Member
    Posts: 28

    When using retaining wall block to raise a patio, say 2 - 3 foot height is there anything that should be used to tie the wall back into the base of the patio? Geogrid? Or will the water be a non issue with a compacted base within the wall. I guess my question is, is there anything that needs to be done with the wall to keep it from coming down? What if it is along the side of a driveway where it is bearing a more significant load? Thanks in advance.
     
  2. cgland

    cgland LawnSite Bronze Member
    Posts: 1,929

    Use geogrid for sure. I like to connect opposite sides of the raised patio if I can. If not a 6' or 8' pull will be more than sufice.

    Chris
     
  3. neversatisfiedj

    neversatisfiedj LawnSite Bronze Member
    Posts: 1,028

    Is that a standard or just your practice Chris ? Just curious. I would not think you would need grid.
     
  4. mbella

    mbella LawnSite Bronze Member
    Posts: 1,284

    Redbear, I'm not really sure what you're asking. Geogrid has nothing to do with drainage.

    Usually, when we build a raised patio, there are sitting walls around the patio as well. In that situation, we will pitch the patio away from the house and install micro strip drains at the base of the sitting walls on the end where the water is directed.
     
  5. Redbear

    Redbear LawnSite Member
    Posts: 28

    Mike, thanks for the response. I'm not figuring on using the geogrid to provide drainage but just to stabilize the standing wall. Let's say I have a patio that is raised against the house 2 - 3 ft. Should I provide a geogrid once the retainer is built to keep it from falling over in a few years or are you suggesting that as long as the slope is towards the front of the wall and drainage strips are provided that there would not be enough pressure on the wall to worry about tying it back into the base. Does this make sense??
     
  6. UNISCAPER

    UNISCAPER LawnSite Bronze Member
    Posts: 1,426

    You need the grid to keep the back pressure from blowing the sides during the winter freeze cycle and to stabilize the load from the eweight of the pavers, concrete or dirt on top of the patio..

    Along the side of a driveway you need strata-grid to support the wall because there is a live surcharge from the cars rolling across the drive. Kind of like using a jackhammer effect on the wall. Grid used on a driveway wall should be Strata 500, or 550.
     
  7. mbella

    mbella LawnSite Bronze Member
    Posts: 1,284

    Redbear, how high is the tallest part of this retaining wall and what material are you using to construct the retaining portion?
     
  8. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Posts: 6,412

    For our 2-3' raised patios, we do not use grid.

    And we have been doing raised patios for 6 yrs.

    There really is no surcharge on the walls for a raised patio, as there is for a wall that is holding a hillside in place.

    Have you pavers installed with a pitch so the water rolls off.

    Also we frequently have decorative planters at the fronts. With drainage pipe below, designed to take the water away.


    Works for us!
     
  9. cgland

    cgland LawnSite Bronze Member
    Posts: 1,929

    Using grid on raised patios is a standard. At least EP Henry recommends it. there is a lot of pressure on those walls and with the freeze/thaw...it just adds to everything. We always use it.

    Chris
     
  10. UNISCAPER

    UNISCAPER LawnSite Bronze Member
    Posts: 1,426

    Keystone engineering recommends grid as well. When we used Unilock in the midwest, the chaneled system would fail unless you used grid, because the freeze would push the walls apart. Lay in some grid, problem solved.

    Put it this way, it can't hurt anything, and the cost is minimal. if the patio fails, then it costs alot.
     

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