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Building Foundation
constructionjargon.com
Foundation - First
Task
The location of the foundation is determined by the site survey or plot plan.
The location of the foundation is determined by the site survey or plot plan.
The plot plan will
show all property line setbacks, dimensions, easements, and any other normally
determined by flood plane restrictions or city and county codes.
The
surveyor can provide a marker or benchmark that serves restrictions
that might be required.
Another
important item required for the foundation is the elevation of
the foundation.
The
elevation is normally determined by flood plane restrictions or city and county
codes.
The
surveyor can provide a marker or benchmark that serves as a reference to
establish the finish floor elevation (FFE).
In order
to be able to start the foundation, the building pad needs to be
complete.
If fill dirt
is required, it needs to be compacted and rough graded to the correct elevation
Once the pad is complete and the corners established, batter boards can be put
up.
The batter
boards and string lines will allow you to get a true picture of the
footprint.
Once the
pad is complete and the of the house and finish floor elevation. After the
string lines are checked for correct dimensions and corners established, batter boards can
be put up.
The
batter boards and string lines will allow you to get a true picture of the footprint
of the house and finish floor elevation.
After the
string lines are checked for correct dimensions and being square, you will be
ready to start putting up forms and digging footings.
The foundation
forms can be wood as in most residential construction or metal as in
commercial construction.
Once
the forms are set, they need to be braced off in order to prevent
the concrete from pushing the forms out.
After the
foundation forms are set and braced, the underground plumbing can
be installed. The plumber can use the form boards to lay out the position of
the plumbing walls and pull string lines.
With the
plumbing wall lines in place, the plumber can dig the plumbing ditches and be
sure that the plumbing is installed correctly.
After the
plumbing is installed, the ditches should be left uncovered until inspected by
county or city
inspectors.
inspectors.
Sanitary
lines are checked for slope and for leaks. Sanitary lines should have at least
a 1/4 inch slope per foot.
The sewer
lines are checked for leaks by using a ten foot stack test.
The stack
test is accomplished by extending the main vent stack, usually a 3 inch PVC
vent up ten feet.
The whole
house sewer system is then filled with water up to the top of the ten foot vent
stack. All the underground plumbing connections are then checked for leaks.
Concrete
is one of the main building products used in the construction of a house.
Depending on where the concrete is used in the construction process, it can
become a very critical factor in the overall structural strength of the house.
Just
because the concrete comes premixed in the concrete truck does not mean that
the concrete is always good.
In normal
residential concrete, the first conversations might be with the concrete
company's outside sales person.
The size
of the foundation and how much concrete will be required are
usually the first questions to be answered.
The
quantity of concrete is expressed in "yards". One cubic yard of
concrete is equal to
twenty-seven cubic feet of concrete.
twenty-seven cubic feet of concrete.
An example
would be if there was a hole three feet wide, three feet long, and three feet
deep it would require one yard of concrete to fill the hole.
Another
value that is used when pouring sidewalks and driveways is that a yard of
concrete will cover eighty one square feet of area (driveway or sidewalk) when
the concrete is four inches thick.
The next
issue discussed might be the strength of the concrete.
Years
ago, the only strength concrete used in house foundations was 2000 psi (pounds
per square inch) concrete. It's not unusual today to see builders pouring 3000
psi and 4000 psi concrete, depending on the size and complexity of the project.
Some of
the larger homes are designed by an architect and might require a structural
engineer. The structural engineer might require mix designs from the concrete
company for his approval.
The sales
person might ask next what kind of "slump" is required. This is
sometimes where the concrete subcontractor and the builder might try to reach a
compromise.
The lower
the slump the greater the strength but the harder the concrete is to work. The
higher the slump the lesser strength but the easier
the concrete is to work.
the concrete is to work.
When a
structural engineer is involved, he might specify that the concrete is to be
3000 psi with a three to five-inch slump.
If this
is specified, it is very important to stay within these limits do not allow
anyone to add water to the mix on site without permission from the individual
doing the testing.
If the
concrete is being pumped, there are additives that can be added to the mix in
order to
allow a higher slump but not jeopardize the strength of the concrete.
allow a higher slump but not jeopardize the strength of the concrete.
These
additives can also be used in dry and windy climates to allow a wetter mix and
hopefully prevent surface cracking due to the fast dehydration of the concrete.
If the
concrete is tested, the slump might be checked every fifty yards and the
cylinders might be taken at the same interval.
Concrete
cylinders are taken and tested to verify the compressive strength of the cured
concrete.
The
cylinders are compressed and broke at specified intervals. A cylinder broke
after 28 days should break at the designed strength or greater.
Also,
usually the temperature of the concrete will be checked at this time. The
temperature of the concrete might become more of a factor in the summer rather
than the winter.
A rule of
thumb might be that if the concrete temperature is above 95 degrees it is not
acceptable to pour in the foundation or footings.
Sometimes
a good starting point to monitor the temperature of the concrete in a truck is
to check the ticket and see when the truck was loaded at the plant.
In warmer
climates, the longer the concrete is in the truck the hotter the mix. In cooler
climates the temperature might not be out of range but the time in the truck
might become a factor.
Usually a
rule of thumb might be that, if it has been forty five minutes to an hour since
the truck was loaded, the load may have started setting up and might not be acceptable
to use.
As you
can see there are a few more things to consider in foundation concrete
other than just pouring the concrete out of the truck.
As in
most any other construction process, a little pre-planning and basic knowledge
might prevent a major mistake that could cost a lost of time and money.
As stated previously,
the foundation is one of the most important phases in the
construction of a house. This phase will require you to be familiar with reading
plans, dimensions, and formulas to determine quantities of
required materials.
Some of the more
common quantities will be expressed as length, width, depth, linear feet, board
feet, square feet, cubic feet and cubic yards. All the materials in the
foundation will be ordered and bought with one of these descriptions.
In order for you to
be able to estimate and order materials correctly, there are certain formulas
that can help you calculate the correct quantities of concrete.
The following formulas are
ones that will be necessary in order to calculate and order the required
material for your foundation.
Linear Feet is
probably the simplest quantity to calculate. Lumber yards sometimes sell lumber
by the linear foot which makes it easy to calculate the
cost per piece.
cost per piece.
Linear feet = number
of items X the item length
220- 2 x 4's lumber X 16 feet in length = 3520 linear feet
220- 2 x 4's lumber X 16 feet in length = 3520 linear feet
Lumber is one of the
main items that might be bought by the linear foot for a foundation. If you dig
footings, labor might be charged by the linear foot.
Board Feet will add two other
dimensions to calculating the cost of materials. Lumber suppliers sometimes
sell their lumber per thousand board feet.
A board foot is one
linear foot of lumber - one foot wide - one inch thick. A 1x12 piece of pine
which is 12 feet long will equal 12 board/feet.
In the same way a 2x6
piece of pine 12 feet long will equal 12 board/feet.
Board feet = Linear
feet X ((thickness inches X width inches) / 12 inches)
(3520 linear feet of 2x4) X ((2-inches X 4 inches) / 12 inches) = 2347 Board Feet
(3520 linear feet of 2x4) X ((2-inches X 4 inches) / 12 inches) = 2347 Board Feet
Lumber may be sold by
the board foot form the building supply. The board foot price will be expressed
so much per thousand board feet.
Example: 2 x 6’s
might be sold as 565.00 per M (Thousand board feet). This will equal .565 cents
per board foot.
Square Feet is a simple process
of multiplying the length X the width. You will need to know how many square
feet there is in the foundation in order to estimate how much vapor barrier to
buy and to determine how much the termite pre-treat will cost.
Square Feet = Length
X Width
Cubic Feet adds one other
dimension to square feet. This dimension is depth. Items that require you to
know the amounts of cubic feet are fill dirt and concrete.
Concrete and fill
dirt are both sold by the cubic yard. There is 27 cubic feet in a cubic yard of
fill dirt and concrete.
Cubic Feet = Length X
Width X depth
Cubic Yard is used to
determine how yards of concrete or fill dirt might be needed for the job. There
is 27 cubic feet in a cubic yard of fill dirt and
concrete.
concrete.
Cubic Yard = Total
Cubic Feet / 27 cubic feet
I have over thirty
years experience in residential construction. I have managed projects from
one single family home to projects consisting of over four hundred homes. During the past
thirty years, my projects have demanded a knowledge of every aspect of construction including
site work, utilities, streets, playgrounds, club houses, swimming pools, and landscaping. I have
experienced the ups and downs of the industry and have probably heard every excuse there is
for not wanting to do a job a particular way. I always have had the philosophy that if I did not
know as much or more about the task being done than the sub doing the work, I would be at a
disadvantage. I have tried to put together some topics and articles that should help someone
not familiar with construction to get a better knowledge of particular tasks in the construction of
a home and be able to talk the talk during the process. The topics in this website are not
necessarily true for all parts of the country. The construction process will change depending on
soil conditions and climate. I appreciate your visit to my site and hope that your construction
experience is good.
one single family home to projects consisting of over four hundred homes. During the past
thirty years, my projects have demanded a knowledge of every aspect of construction including
site work, utilities, streets, playgrounds, club houses, swimming pools, and landscaping. I have
experienced the ups and downs of the industry and have probably heard every excuse there is
for not wanting to do a job a particular way. I always have had the philosophy that if I did not
know as much or more about the task being done than the sub doing the work, I would be at a
disadvantage. I have tried to put together some topics and articles that should help someone
not familiar with construction to get a better knowledge of particular tasks in the construction of
a home and be able to talk the talk during the process. The topics in this website are not
necessarily true for all parts of the country. The construction process will change depending on
soil conditions and climate. I appreciate your visit to my site and hope that your construction
experience is good.
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