Screw piles or Bored piles

Discussion in 'Development' started by TML, 23rd Feb, 2016.

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  1. EN710

    EN710 Well-Known Member

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    25 years is depend on the builder, but mandatory only need 7 years
     
  2. Rockstar

    Rockstar Well-Known Member

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    My last duplex had to have screw piles because of the unstable sand fill + in a flood zone. Some of the piles went down 14m! Would have been impossible to bore holes into the sand as water table was only 1.5m deep. The holes would have begun collapsing very quickly. After the piles were in we filled them with very wet 32mpa concrete.
    Cost was 20k for 54 piles. I then poured 400 x 400 footings onto the steel pile and laid block piers to take the bearers. I would only ever use them again if there was no other alternative.
     
  3. J Mac

    J Mac New Member

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    Hi we purchased a block with 3 metres of fill months ago and it has recently titled.
    The developers say the fill is compacted to Level 1....not sure what that means? The developer lead us to believe that as the block is flat, and compacted to Level 1 that we wouldn't need any screw piles. The engineer says that they are necessary....this is adding a further $5000 almost to the build. Do we have any recourse....would screw piles be needed? We are novices and still learning!
    If someone could shed some light we would be very grateful.
    Thanks
     
  4. TML

    TML Well-Known Member

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    I came across different builders and each builders came back with different options - screw or bored.

    from speaking to the builders, bored piles is better as they are made of concrete and last a life time. However, they will need to drill the ground until they find rock. In this case it will cost more as it may be quite deep until they hit rock.

    apparently with screw piles dont need to hit rock and the concept is similar to a general purpose metal screw you buy from bunnings, it screws into the ground so it locks onto the soil. this assuming the soil is compacted.

    my other builder sugguested is not a fan of the screw arrangement as it is metal and can corrode and on top of that it depends on the soil type. If there is movement in the soil so will the screw.

    My recommendation would be to use bored piles but they may be a alot more expensive depending on how far they hit rock.
     
  5. vbplease

    vbplease Well-Known Member

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    To use screw piers and not use galvanised steel would not be wise.. if reactive soil is such an issue the builder could incorporate adjustable supports within the footing. They're very common in se QLD. Ezipier Adjustable Steel Piers (Alternative To Timber & Concrete Stumps) - Spantec
     
    Last edited: 8th Nov, 2016
  6. TML

    TML Well-Known Member

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    Yes VB, i should have said hot dipped galvanised steel screw piles which is should be used. As soil regardless if it is reactive or not there is water content which will eventually corrode.
     
  7. TML

    TML Well-Known Member

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    vb after reading your hyperlink website i think we are not talking about the same thing.

    Iam referring to screw piles for stabilising the foundation. see web link below.

    Piletech : What are Screw Piles?
     
  8. vbplease

    vbplease Well-Known Member

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    Sorry, my link was just to show you what the 'adjustable connection' is about. Depending on how reactive (expansion/contraction) the soil is, the builder could incorporate adjustability into the screw piers.

    I wouldn't be too worried about corrosion issues using h.d.g. A design life of 100 years would be no problem. Have a quick read of this link.. in particular the graph on page 8. http://www.bluescopesteel.com.au/files/Inground_Performance_Galvanised_Steel1.pdf