Foundation Systems

Foundation Systems
What Does the
Foundation System Do?
• Support the “load” or weight of the
house and transfer it to solid ground
• Repel water that may accumulate in
the ground so that the basement stays
dry and healthy
• Anchors the house solid to the ground
Major Components of a
Foundation System
Strip (or Wall) Footing
Column Footing
Foundation wall
Column or Pier
Weeper or Drainage Pipe
Basement Floor
The Make up of a
Foundation System
• Step 1 - Excavation
– A cut, cavity, trench, or depression made
by removing earth. Excavations are dug to
prepare the site for footings, foundations,
and the installation of pipes for site
The Make up of a
Foundation System
• Step 2
– Forms are constructed on the undisturbed
soil at the bottom of the excavation. It
might look like this…
Key Terms
• Form
– Any framework designed to contain wet concrete.
Forms can be made of steel, lumber, or a
combination of lumber and plywood.
• Footing
- A base providing a larger bearing surface against
the soil for load bearing parts of the structure.
Footings are generally made of concrete poured
into place.
Key Terms
• Keyway
– The part of a footing that locks the
foundation walls into the footing. Usually a
groove cut into the top of the footing.
• Rebar
– Reinforcing steel rods that are embedded
into concrete to make it stronger. Rebar
has a patterned surface that makes it bond
to concrete.
The Make up of a
Foundation System
• Step 3
– The foundation wall is constructed on top
of the footings once they are fully cured.
Foundation walls may be constructed out
of concrete, block or even pressure
treated wood…
Key Terms
• Foundation Wall
– The wall that sits on the footing and transfers the
load of the house from the mudsill down to the
footings. Basically the foundation walls are the
basement walls.
• Anchor Bolt
– A bolt, usually L shaped that is embedded into the
foundation wall. It is used to securely fasten the
sill plate to the foundation.
The Make up of a
Foundation System
• Step 4
– The drainage system or “weepers” are installed.
This consists of a large perforated pipe that runs
around the outside of the perimeter of the
house, beside the footing. It is buried in gravel
and covered with a landscape fabric. The
outside of the foundation wall is covered in a
waterproofing membrane that is designed to
direct any water down to the drainage pipe and
safely away from the house.
Key Terms
• Weepers
– Perforated drainage pipe installed around the perimeter of
the house, designed to capture any water accumulating near
the foundation and drain it safely away, either to the
municipal storm sewers or to a sump pump installed inside
the house.
• Waterproofing Membrane
– Plastic membrane installed on the outside of the foundation,
below the finished grade, or ground level. The membrane
does not make a waterproof seal itself, it just acts as part of
the waterproofing system by creating a “path of least
resistance” for water to travel easily to the weeper pipe and
therefore safely away from the house
The Make up of a
Foundation System
• Step 5
– Backfill. Once the water proofing system is in
place and after the floor has been framed,
(depending on the foundation type) the
excavation is backfilled. Any portion of the hole
that was excavated, that is not now occupied by
the foundation gets filled back in. Typically the
same soil that was removed during excavation is
used for backfill. The backfill is then graded to
ensure that water is not allowed to accumulate
near the house.
Key Term
• Backfill
– The process of filling the unused portion of
the excavation around the house back in.
It is important to ensure that proper grading
is maintained when back filling.
The Make up of a
Foundation System
• Step 6
– Pour the basement floor. Once the drains
have been installed in the basement, the
area up to the top of the footings is filled
with gravel, and then a concrete floor is
poured on top of that.