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estimating formulas

Discussion in 'Hardscaping' started by JJfishes, Apr 21, 2006.

  1. JJfishes

    JJfishes LawnSite Member
    Messages: 14

    Wondering if anyone knows of a site to get info on estimation of bulk materials needed, specifically base material for patios and walks. An example would be 100 square feet by 9 inches deep of COMPACTED material. How much base material do i need in tons or yards.

    Thanks Jay
  2. Bustus

    Bustus LawnSite Member
    Messages: 181

    I'm not sure they are exactly what your looking for, but there have been posts on this topic. Just use the search function and I'm sure you'll find some formulas. Good Luck!
  3. DVS Hardscaper

    DVS Hardscaper LawnSite Fanatic
    Messages: 6,576

    I have a feeling you'll receive varied responses.

    We have been doing full fledged hardscapin for 10 years. And have always been right on the money with the following formula:

    TOTAL SF x inches / 3 / 27 = x 1.2 x 1.5 =

    Ok I'll go further:

    100 x 9 / 3 / 27 = 11.11 x 1.2 x 1.5 = 20 tons

    dividing by 3 is what equates the inches

    multiplying by 1.2 is what converts cu yds into tons

    multiplying by 1.5 is what accounts for compaction.

    This is the only formula I have ever used. (computerized estimating system does it for me), and I do know other folks have other good formulas.

  4. TEC

    TEC LawnSite Member
    Messages: 2

    The way I do is take your SF x base thickness x 10 and divide by 2000
    10 represents 10lbs per SF@ 1 inch compacted 2A modified stone

    100 SF @ 9" = 100*9*10=/2000= 4.5 Tons

    a 10X10 pad & 20 ton would equal a 40" base
  5. cgland

    cgland LawnSite Bronze Member
    Messages: 1,929

    Andrew - Instead of dividing by 3 you should be dividing by 12. 20 tons for a 100 sq. ft. patio @ 9"! That's crazy! I came up with 5 tons or 4.99999 to be exact.

  6. bigviclbi

    bigviclbi LawnSite Senior Member
    from nj
    Messages: 900

    I'd be about 5 tons for 9" but I'd have to say it varies depending upon what you are using as your base.
  7. Mike33

    Mike33 LawnSite Bronze Member
    Messages: 1,649

    This is really funny we get all different answers. I got 4.9 tons but with price of fuel of going back for a small quanity i would get 6 ton. I use sq.' divide by 27 multiply by 1.35 Was wonering how the 1 guy got 20 ton?

  8. cgland

    cgland LawnSite Bronze Member
    Messages: 1,929

    Mike - The price of fuel in no way affects the tonnage needed to cover that excavation!:dizzy:

  9. Mike33

    Mike33 LawnSite Bronze Member
    Messages: 1,649

    My point was formula was 5 ton. I would for this size job get a extra ton because of fuel prices i would not want to be a litttle short and where i have to go to get stone the fuel and time would hurt. You do have to look at your time and fuel these days you can always take a half ton away cheaper than holding the job up.

  10. mrusk

    mrusk LawnSite Gold Member
    Messages: 3,260

    I always over order base material. 90% of the time there is somewhere to dispose of it on site, since i don't have a dump truck.

    Sometimes the customer gets real happy when i spend 5 minutes and fill in some pot holes on there driveway.

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