Pouring a Foundation

Pouring a new foundation for an addition 
 
When you are building an addition onto yourA concrete cutting machine sometimes called a
existing home you will most likely need to pour awall saw or a wet saw is usually powered using a
new foundation for the new addition.  You canhydraulic motor. The main hydraulic pump is
also build your addition on Piers, this is OK forusually mounted to a truck and the saw is
three season rooms or sunrooms but notconnected using hydraulic hoses. Water is used to
recommended for year round living additions, suchlubricate the blade and to control the dust. Make
as bedrooms, bathrooms and kitchens.  Beforesure you protect the inside of the basement with
your contractor begins excavation he should havea plastic sheet.
the area surveyed for any underground utilities.
Underground gas lines, power lines, sewer lines, 
water supply lines, septic tanks, oil tanks are just 
a few of the possible obstacles your contractorA concrete pump is needed when a cement
may need to go around. If any of these are inmixer cannot access the construction site. Many
the way they will need to be moved prior totimes additions are built in the back of a house
excavation.and there is not enough space for a large cement
                   mixer to get around the sides of the house.
 Sometimes a cement mixer has enough space to
A typical foundation will consist of three primaryget to the cosnstruction area but there is a hill
parts, (1) the footing (2) the wall (3) the floor. Athat is too steep, or sometimes the cement
typical foundation is almost always poured in themixer would have to drive over a septic tank to
three steps.reach the construction area. If you have a septic
 tank make sure it is marked on you property so
First the foundation area will need to bethat no heavy equipment can drive over it. A
excavated to the desired depth. The depth willcement mixer vegicle that is full of concrete can
depend on the type of foundation. A fullwieght 80,000 pounds.
basement will require a hole to be excavated at a
depth of about 8-10 feet. A crawl space will 
require a hole to be excavated at a depth of 3-4   
feet. The footing should always be at leastPinning the new wall to the existing involves drilling
42” below grade (surface of the grass) in thethe existing foundation and driving in rebar. The
northeast. Your contractor should know all ofrebar will act as a mechanical fastener between
your local codes. If you are adding a full basementthe new wall and the existing wall. This is a must.
don’t forget that your contractor will cut anIf your contractor doesn’t do this there is a
opening from the existing basement to the newgood chance that the concrete wall will break and
basement. That can get messy so make surecave in when he is back filling. These pins keep
that all of your valuables in the existing basementthe new wall from pushing in when there is a lot
are covered to be protected from excessiveof wieght from vehicle driving around the
dust and make sure that your valuables are farperimeter of the foundation.  
away from the area where the cutting will be 
done. A concrete wall cutting machine is very 
dusty and messy.Waterproofing the outside of a foundation wall is
 very important. This can be done either by rolling
(1)  The footings have been poured and the areathe water proofing on or  spraying it on. The
under the slab and around the footings is filledwater proofing should cover the walls, where the
with crushed stone to help with drainage so thatwalls meet the footings, and especially where the
water does not penetrate through the foundationwalls meet existing foundation. The seam where
and enter  the basement. Plastic drainage pipingthe walls meet the existing foundation is the most
has been installed around the outside of thecrucial area to water proof. A good contractor will
footings and covered with geofabric. A groove iscover this area multiple times. That seam is the
carved in the top of the foundation so that themost vulnerable point where groud water can
newly poured concrete for the walls will beenter the basement. Waterproofing material is
fastened to the footing. This groove prevents theusually tar based or rubber based.
wall from sliding off of the footing when lateral 
pressure is applied. 
 Drainage is the most important method to
 eliminating water intrusion in your new basment. A
(2)  The walls have now been poured.  Once thegood drainage system should take any water
walls are poured the forms are stripped and theaway from the foundation. Water that’s runs
outside of the foundation walls get backfilled.off of the roof should be controlled using gutters
Notice the perimeter fencing around theand down spouts. The downspouts should have
foundation. It is very important that yourextensions on the groound so the rain water is
contractor always has perimeter fencing upnot dumped directly at the base of the
around the foundation, especially overnight whenfoundation. You can also have your contractor lay
the contractor is not there.  This is extremelydraiange piping around the foundation. Solid
important; your homeowners insurance could bedrainage piping can be used to collect the
liable for any injury in the case that someone fallsrainwater and discharge it far away from the
in. A thick plastic sheeting has been placed overhouse. Perforated drainage piping can be installed
the crushed rock to help in preventing moisturearound the perimeter of the foundation to collect
from getting through the concrete slab and intoground water and carry it away from the
your basement. Once the plastic is placed we arefoundation.
ready to pour the floor. 
  
  
Pre-Cast basement entrances are installed after
(3) Once the concrete floor has been poured wethe walls have been poured. The precast
are ready to begin framing.  The concrete floorbasement entrance can be ordered from a local
of your basement should be smooth and level. Aconcrete supply company. Usually your contractor
good foundation contractor can do this relativelywill take care of ordering the unit. The supply
easily.company that delivers the basement entrance will
 also install it. It is usually craned into place where
   the concrete contractor has left an opening for it.
 It is bolted to the new foundation and
 waterproffed. Then the actua metal door will be
  installed. Most companies use Bilco doors.
  Don’t forget to paint them at the end of the
  project, the factory color is usually just a primer
  paint.
The Details