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Screw piles or Bored piles

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

  1. TML

    TML Well-Known Member

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    hello engineers or developers...

    have you ever been ask the option of Screw piles or Bored piles for your foundation?

    which one is better?
     
  2. bob shovel

    bob shovel Well-Known Member

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    Cheaper one :p

    Probably depends on geotech, access, price, design. Let the engineer take care of it, or give you pro's and cons for the site
     
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  3. EN710

    EN710 Well-Known Member

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    Would be interested to know. Concrete pier is recommended for my land, screw piles are additional cost on top (of fixed cost)
     
  4. bob shovel

    bob shovel Well-Known Member

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    It depends on the site and the sorcery that the engineer decides to put into play ;)

    To get the support on one site may require a 1m concrete pier for $x but screws for the same site may need to be 5m deep costing $5x
     
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  5. EN710

    EN710 Well-Known Member

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    The only reading I found said you would need more screw piles to do the same job as concrete piers.

    Talk to structural engineer is best. I talked to one and he said, depends on what you want - you can go to the minimum or get the higher spec (there is no limit to how high spec you want it)
     
  6. TML

    TML Well-Known Member

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    what do you mean by a higher spec?


    I spoke to a builder on the phone yesterday and he said since screw piles are made of steel it is likely it will be rusted and they last approx. 60 years.

    As opposed to concrete which will last alot longer.
     
  7. EN710

    EN710 Well-Known Member

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    As in, you can over engineer your slab, and add piers even when not needed etc.
     
  8. TML

    TML Well-Known Member

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    ar ok!!!! got ya

    do you know how deep does the bored piles normally goes down to?
     
  9. EN710

    EN710 Well-Known Member

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    Depends on your engineer spec :D

    For example, my land have up to 1.5m of fill. Engineer I talked to said that if it's up to him (he is not engineer from my builder), he'd concrete pier it to 2.6m
     
  10. bashworth

    bashworth Well-Known Member

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    I have written about the issues on my blog.

    Not sure if I am allowed to leave a link. . . . but if you Google "anewhouse" and "screw piles" you should find the information.
     
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  11. EN710

    EN710 Well-Known Member

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  12. Chomp

    Chomp Well-Known Member

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    Why don't ask a piling subcontractor, if pricing is similar then get your engineer to offer a solution for using both and then get pricing. I'm pretty sure bored piling will come in cheaper.
     
  13. norwoodman

    norwoodman Well-Known Member

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    It depends on the structure being proposed and the geotech conditions for the site. If the ground conditions are good enough, you may not require piles (a raft footing or pad footings may work instead) at all depending on the size of the structure being proposed.

    Where piles are required, screw piles would normally be used where the bearing capacity of the ground is low but the weight of the structure going above doesn't warrant the use of bored piers. Its main advantages against bored piles would be not having to remove excavated material and construction time savings.
     
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  14. bashworth

    bashworth Well-Known Member

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  15. TML

    TML Well-Known Member

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    Thanks Basworth.

    I have read your website but it only talks about the advantages.

    What are the disadvantages?

    As pointed out earlier, a builder said to me that since the screw piles are made of steel tube it will rust and may last up to 60 years?

    could you please comment on this?
     
  16. bashworth

    bashworth Well-Known Member

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    Only disadvantage would be cost of the job for an open site where soil removal would not be an issue.

    Normal screw piles are fairly thick steel.

    Corrosion for plain steel piles in natural ground will be in the range 0.12 - 0.3 mm in ten years.

    Galvanised steel even less.


    If you want to read a research paper here is a link http://www.helicalpileworld.com/Dealing_with_Corrosion_-_Kevin_Davies.pdf

    How long do you expect the structure you build on the piles to last?
     
  17. TML

    TML Well-Known Member

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    thanks Bashworth

    i dont know if there is a standard but i heard from a builder that the structure should last at least for 100 years.

    Do you know of a standard that says that?
     
  18. bashworth

    bashworth Well-Known Member

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    A well built structure will last that long. . . but how many do.

    I often see houses demolished that are less than 30 years old.

    In many post WW2 suburbs a very large proportion of the houses have been demolished.
     
  19. EN710

    EN710 Well-Known Member

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    Hmm is it written somewhere in Australian Building Standard?
    Builders mandatory structural warranty is only 7 years

    And I reckon I won't be alive 100 years from now
     
  20. TML

    TML Well-Known Member

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    i thought it is 25 years for some builders??