Bored Piers or Screw Piles

hi5 · Aug 09, 2020 1:57 pm

Hi,

We have received our engineering drawings & building permit back and it specifies bored piers in the drawings & permit for my 'p' class site.

19 x 450 DIA. MASS CONCRETE BORED PIER TO 2000 DEPTH
20 x 450 DIA. MASS CONCRETE BORED PIER TO 3000 DEPTH

"STEEL PILE ALTERNATIVE IS AVAILABLE AS AN OPTION HOWEVER HAVE NOT BEEN DESIGNED UNDER THE SCOPE OF THIS PROJECT"

In our contract document, I can see we have been charged for just the screw piles as an additional $18,000 but nothing for bored piers.

So my question is:
1. Should I insist on screw piles option or go with bored piers as proposed in the drawings
2. Is the cost differential significant between bored piers vs screw piles?

theshack · Aug 10, 2020 10:54 am

There is an obvious inconsistency between the engineering design & building permit vs the contract documents which will have to be corrected.

In terms of cost this site has a natural bias towards screw piers but does have an estimator between the options
https://www.idealfoundations.com.au/scr ... red-piers/

Given the bias / simplistic calculator I would treat the estimated costs with caution but at 2m+ depth screws piers will start to become more cost effective.

StructuralBIMGuy · Aug 10, 2020 11:49 am

The decision/price to charge is made by the Builder
Piles generally cost $100 to $150 ea
With higher number of piles Engineers/Builders favour bored piles as they tend to work out cheaper
But Builders will still charge full $ticker price >$450 ea.
This post & Pile Calculator just confirms what we know happens
Thanks for the link
Hi5 Please Sort out the engineering and footings costs before you proceed any further and avoid further $ticker $hock
Cheers

hi5 · Aug 10, 2020 12:16 pm

StructuralBIMGuy

The decision/price to charge is made by the Builder
Piles generally cost $100 to $150 ea
With higher number of piles Engineers/Builders favour bored piles as they tend to work out cheaper
But Builders will still charge full $ticker price >$450 ea.
This post & Pile Calculator just confirms what we know happens
Thanks for the link
Hi5 Please Sort out the engineering and footings costs before you proceed any further and avoid further $ticker $hock
Cheers

Thanks StructuralBIMGuy, I also read on this forum about corrosion issues with steel pile and hence concrete is better. What is your view on that?

hi5 · Aug 10, 2020 12:26 pm

theshack

There is an obvious inconsistency between the engineering design & building permit vs the contract documents which will have to be corrected.

In terms of cost this site has a natural bias towards screw piers but does have an estimator between the options
https://www.idealfoundations.com.au/scr ... red-piers/

Given the bias / simplistic calculator I would treat the estimated costs with caution but at 2m+ depth screws piers will start to become more cost effective.

Thanks theshack, This site is really good and helps a layman like me compare the differences between the two.

Do you have a view on the corrosion issue with screw piles that some others have raised in this forum?

StructuralBIMGuy · Aug 10, 2020 12:51 pm

What is the depth of uncontrolled fill and Bearing Capacity at that depth...so more information is required
You will also need to consider, Slope/contour, Type of footings, Stormwater,Retaining, Ground pH, etc
Sounds like they haven't completed a full Site assessment to date either ....so be prepared for further price increases
The fact that items aren't included doesn't mean the builder can't charge for them later as a variation