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In July of this year I posted a blog regarding ICC
requirements and residential permits, read previous blog
here. In that blog I posted some difficulties with ICC
regulation and residential permits. Specifically that the requirement of soil
borings and its reverse effect on helping homeowners.
On smaller residential projects the requirement soil tests
are expensive and burdensome especially on small projects. A two pile project
might cost $3000 and the soil boring typically costs more than that. This has
an effect of discouraging the homeowner for making the decision to do any work
at all because it is so burdensome. I have had many home owners cancel the
project because of this.
How is this better? They now are doing nothing or finding a contractor to do it
without permits.
If this procedure produced any substantial benefit that
would protect homeowners I might agree that it is worth the cost. However I
don’t believe that is the case. Let’s look at the facts.
- I think we are trying to solve a
problem that does not exist. How many failures have occurred as a result of a
lack of soil information on lightly loaded structures? Does anybody know that information? I certainly
have not heard of any cases. As far as I know there has been very little
failures as a result borings not being performed. It is possible that with some
pile systems that are less robustly engineered that there have been some
failures. However I am not arguing to abandon the ICC testing and verification
altogether. Only the requirement for soil boring.
- In residential applications the factors of
safety are so high that the soil information almost becomes irrelevant.
(usually 6:1 or more) Helical and push pile products return soil information
that can verify the load carrying capacity at each installation, making soil
verification much less relevant. In fact each pile installation can be viewed
as a mini pile load test which in most engineer’s eyes is more reliable than
calculations from soil borings.
- On commercial projects with heavy
loads and more complicated loads soil borings provide helpful information to
simulate and determine which pile is best suited for the application. On almost
all residential projects that information will not change the design of the
pile because the pile is so overdesigned for residential loads. So in essence
we are going through an exercise that has no
effect on the installation pile or procedure.
- Because of the above noted issues
and the fact that most installers understand these issues intuitively, the
overwhelming majority of pile installations on residential projects are done
without borings, totally ignoring the ICC’s requirement. If this is the case, then
what kind of precedent is this setting up in the industry where a requirement
is universally ignored?
So why does this unneeded
and unhelpful and counterproductive acquirement continue? Partially I think
because it was built into the code by structural engineers who have less of the
comprehensive knowledge of geotechnical factors. The IBC section 1810 calls for
all deep foundation products to have soil borings. This is because originally
deep foundation products were things like caissons and micro piles that do not
return soil information or any verification of their carrying capacity. When
helical piles were brought into the code, no one could convince the ICC that it
was not needed at least in a lightly loaded structure.
Because of this when code officials read the IBC codes and ICC ESR’s for helical
piles, the lack of understanding is transferred to municipalities who chose to
enforce the code as written to protect themselves from potential lawsuits, even
though I don’t think there have been any structural failures to speak of let
alone suits as a result.
Critical thinking, cost/benefit, and big picture thinking
seem to be absent from this whole process and everyone wants to simply point to
the poorly thought out precedents that have no real world justification, to justify a lack of thoughtful responses.
