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Concrete
& Foundation Requirements
for Steel Buildings
Please
Note: Through the years
we have seen many sets of engineered
plans for our buildings come through
our offices. This has given us
the opportunity to examine different
concrete and foundation requirements
for many different parts of the
country. While we have attempted
to provide you with accurate information
with regards to what your concrete
and foundation requirements will
be, this information is not guaranteed
to be what an engineer would specify
for your unique circumstances
but is intended to be used only
as a guide in your concrete requirements.
Our
buildings can be anchored on the
ground (without a concrete floor)
or on concrete. Before getting
into particulars, if you are in
an area that has a frost line,
you will need to be approximately
12" under that frost line
for your perimeter footings. This
depth requirement for colder areas
applies to ground anchoring as
well.
The
below described concrete applications
do not account for frost line
requirements.
When mounting to the ground, you
will be required to dig a post
hole approximately 10” in
diameter and 30” deep every
five feet or every four feet depending
upon whether you have purchased
a 5’ On Center system or
a 4’ On Center system.
This
type of mounting system is called
a “caisson”.
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30"
Ground Anchors are supplied
to you
with your building kit if
you specify
"Ground Mount" |
Assemble
your base rails and lay them in
place, marking where your holes
should be dug. (A 16 D nail poked
into the ground through the pre-drilled
hole in the base rails works very
accurately for this.) Next, use
a post hole digger or auger and
drill your holes 30” deep.
Clean out the holes. You would
now lay out your base rails according
to the instructions and drop the
ground anchors into the pre-drilled
holes. Use a 2500psi concrete
(pre-mixed bags or mix your own)
and, using a shovel, fill the
holes.
You
should wait at least seven days
for the concrete to properly set
before moving on with the assembly
of your building.
This
is the same procedure used for
ground mounting our carport structures.
Size the slab.
You should make your slab 4”
wider then the width of the building
and 6” longer. This is so
you don’t break or crack
the edge of the slab when affixing
the concrete anchor expansion
bolts into your slab.
Concrete
Floor: Your floor should be
a minimum of 4” thick. Make
it 6” thick if you are intending
large vehicles such as trucks
or larger RVs to be parked on
it. The concrete should be a minimum
of 2500 psi concrete with fiber mesh
reinforcement added at the batch
plant OR #3 rebar on 24”
centers. You should also consider
going with a concrete mixture
of 4000psi along with the extra
two inches of concrete if you
are intending more than a normal
amount of weight. Be sure to saw
cut expansion joints within an
appropriate time after the pour
is finished or trowel in the expansion
joints while the finishing is
occurring.
The
cost, including expansion joints,
would run $4.50 per square foot
in our local area for a 4"
slab.
Footing
Requirements:
(International Building Code 2000
or “IBC 2000” requirements)
At the same time you pour the
floor, you are going to pour the
perimeter footings. This is called
a monolithic pour or monolithic
slab. Perimeter footings need
to be 12” deep (you can
include the 4” of floor
as part of the 12”) and
16” wide. The footings will
have to have two #4 rebar lengths top
and bottom, continuous run around
the complete perimeter.
In
our local area, the footings would
cost approximately $11.50 per
lineal (running) foot.
That’s
it. If your building department
is still using UBC 1997 (Uniform
Building Code), which many of
them are, your footing only needs
to be 12” wide. That should
knock about $1.00 per lineal foot
off the above footing price estimate.
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