Building up to level patios.

Discussion in 'Hardscaping' started by PerfiCut L&L, May 30, 2006.

  1. PerfiCut L&L

    PerfiCut L&L LawnSite Senior Member
    Posts: 458

    Ive heard a number of stories as to what to use what not to use to build up in order to level things off. So far I have not run into a job that required a large buildup of say... more than a 12 or 18" inches. With the exception of a small landing and steps we just did.

    Anyway, my question is... when you have a large patio that needs to be backfilled 2, 3, or 4 feet in some cases what material and method do you use to accomplish this.

    Ive heard "NEVER" use top soil, always use stone. Ive also heard, its ok to use top soil as long as its not sandy, up to a certain height, compacted frequently then, a good 8 inches of Crusher Run or equivalent sub base.

    Again, whats been your experience and what do you do to accomplish this?
     
  2. orionkf

    orionkf LawnSite Member
    Posts: 122


    I'd go with whatever you use for your regular base, done in lifts. Maybe consult an engineer about local non-expansive soils if it is excessively tall or large.
     
  3. Pavers Plus

    Pavers Plus LawnSite Member
    Posts: 83

    I'd say there are 3 methods that I'd use in building a raised patio, depending on the height needed to raise.

    If I need to raise less than 15" +/-, I'd probably use the same crusher run (CR/8 or CR/6 in Maryland) material I normally would, using the appropriate lifts depending on the machine. Also using stabilizing fabric below the base.

    If the height gets above 15", I would tend to use 57 stone to raise up most of the height. I'd put the stabilizing fabric between the soil and the 57 stone. The 57 stone is compact to about 95% when dumped from a wheel barrow. Then when I get about 4-6" to the top of the base height, I would put down more fabric between the 57 stone and the crusher run and install that as I normally would.

    A third method would be to build up the walls to where you want them to be and then put fabric in the structure and fill the raised patio with flowable base/fill material.

    under no circumstance would I use "topsoil" or dirt. Just too hard to achieve the appropriate compaction in reasonable times and being assured it's compact.

    Hope this helps.
     
  4. XXL Hardscaper

    XXL Hardscaper LawnSite Member
    Posts: 37

    Have you ever used Flowable fill? Do you know the Psi or Proctor of Flowable fill? Do you Know what the actual application of Flowable fill is? I would NOT recommend it in a raised patio situation.I also would not recommend using the combination of 57s and crusher run ( cr-8 ). I would use Cr-6 to bring up and use Cr-8 as final base ( and of course your 1 inch of bedding sand ). Anything over 2 1/2 feet I also incorporate grid.
    But hey Ive only been doing this for over a decade so what do I know.
    How long have you been doing or should I say how long did you do Install work? 1-2 years? and then do body else there at Pavers Plus has any install experience.
     
  5. Pavers Plus

    Pavers Plus LawnSite Member
    Posts: 83

    XXL Hardscaper, to answer some of your questions, I have not personally used flowable fill, though I have done some significant research on that subject as well as many other subjects pertaining to Concrete Pavers and Segmental Walls. The PSI should be around 150psi, though the PSI is not really that important, since you don't want to have a solid structure. The Proctor density should be near 100%. Flowable fill is definitely a product that you and most other contractors should start looking into soon, because it can only help with future installations. Here is a link for information about flowable fill http://www.flowablefill.org/benefits.htm

    In the course of my installations, we usually used CR/6 for the base and used CR/8 for the final 1" of base + the 1" of concrete sand. We also used all CR/8 on large raised patios, which I regret after doing research on Flowable fill and even mixing 57 stone. I did say that if you use 57 stone that you should separate with stabilizing fabric. There is nothing wrong with this practice. It saves production time and you will not have to worry about as much settlement with the 57 stone. If anyone is doing a raised patio and doing their lifts of 2-4" with the small plates, I can almost guarantee that you are not effectively achieving 98% Proctor Density on the installations consistantly, if at all. Plus the time it takes to tamp 2-3 times or more for each lift adds up significantly.

    I too would recommend using Geo-Grid on raised patios if using CR/6, CR/8 or 57 stone to help stabilize. It is cheaper to put the grid in than to fix the patio later.

    As far as you doing this type of work for over a decade, that doesn't really mean squat to me. I've seen guys doing it for a few years that are light years ahead of guys that have been doing it wrong for over a decade, but what do I know. I see contractors that have been doing "Hardscaping" for over a decade that still insist on using Stone Dust......, does that mean they know what they're doing since they've done it wrong for over 10 years? Also, if you are the owner or manager of your company and not actually doing the installs or watching closely over your crews, how certain are you that things are being constructed properly.

    I actually installed projects with my company for 2 years and worked for another contractor for a year. Now with Pavers Plus for 1 year. My background, if you don't already know, is a licensed landscape archtect in both Maryland and Virginia as well as a licensed contractor. Basically, as a landscape architect, I try to research things to death to make sure the best methods and products are being used and available to other contractors. So, as I stated earlier, your experience of over a decade does not mean a whole lot of squat to me or other younger individuals in the industry that know what we're doing because we research and seek out the best methods.

    Hope this answered some questions for you and others.
     
  6. cgland

    cgland LawnSite Bronze Member
    Posts: 1,929

    Pavers Plus - Can you show me the scientific data stating that clean stone is 95% compacted when dumped from a wheelbarrow? I would also like to see the equipment they used to acheive this measurement. This is one of the biggest farses in the industry. There is absolutely no way to measure the proctor density of clean, uncompacted stone. It is a guess at best and I certainly would not risk my companies reputation by using clean stone as a base material for a raised patio. The only viable options are modified stone compacted in lifts or flowable fill. The only place clean stone has in a flexible pavement system is in a permeable pavement application or possibly as a retaining wall base in a water application. My .02

    Chris
     
  7. Pavers Plus

    Pavers Plus LawnSite Member
    Posts: 83

    Chris,
    I don't have any scientific data backing up the 95% compaction of clean gravel out of a wheel barrow, so probably should not have stated as such. just knowledge passed to me by a couple engineers. You are right, there is no way to measure the Proctor Density of clean gravel, but I think I stated simple compaction. There are too many voids in clean gravel to measure the density data.

    My question would be why is it OK to install clean gravel for permeable situations and not a raised patio. Wouldn't a permeable paver street be under heavier load than the patio. How about when installing a retaining wall and you backfill behind the wall for drainage. Is there worry there about settling of the clean gravel in that situation as a different rate than the other backfill material.

    Again, if I used clean gravel in certain situations, I would make sure all unlike materials were separated, ie: sub-base(clay) from clean gravel from modified stone. I would also run the plate over the clean gravel to help assure maximum compaction.

    If anyone is not comfortable with the clean gravel backfill method, by all means continue as you already do. No harm, no foul.
     
  8. Pavers Plus

    Pavers Plus LawnSite Member
    Posts: 83

    Wouldn't the clean gravel be considered sub-base under the modified stone base. this picture is from Tech-Spec guide 4 from ICPI.

    adam

    tech4_pic8.jpg
     
  9. PerfiCut L&L

    PerfiCut L&L LawnSite Senior Member
    Posts: 458

    Look, I didnt want to start a bashing thread. Just looking to see what people are actually using, what has worked for you and what has not.

    Im not looking for opinionated responses. Facts only please.

    Im sure theres plenty of people here with the experience to answer the question. Like I said in my original post. Ive "head" several ways, what Im looking for is an aswer to what other people are ACTUALLY DOING (USING) to accomplish this.

    To clearify it a bit, Im looking at heights between 12" and say 4' tops. We just did ground level patio with landing at 4'. The landing was small in respect, 5'x9', so filling it wasnt that big of a deal. Few tons of crusher run, compacted in phases, with our sandbase on the top. We use large 90# stones to for the walls to build it up.

    What I''m trying to prepare for is that large patio 14'x30' that needs to be leveled at 2' or 3' heights. The quantity, not to mention the labor to bring that up using crusher run I can only imagine. So I wanted to see if their was another method and how others accomplish this.
     
  10. zedosix

    zedosix LawnSite Silver Member
    Posts: 2,636

    In our climate we must use clear stone (3/8" works best) in all our steps and raised patios. Especially the first 10" to 12" behind the wall. Using compacted 3/4" - is useless, all it tends to do is hold water, freeze and shift the blocks and open the capstones.
    I've seen a lot of changes over the years, mostly positive. Our customers are getting finished products now that last many many years with minimal repairs. In part thanks to sites like this and ICPI. Not that anyone cares but this is my 24th year doing hardscapes. :canadaflag:
     

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