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 drainage. 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.