House foundation
Every house is built on a foundation, Foundation type is based on several factors, such as the house design, the geographical location and climate, soil and moisture conditions, and the project budget.
Depending on when and where a house was built, the foundation may be made of stone, brick, concrete block, or poured concrete.
In New Zealand, we use 3 most common types
Rib Raft Slab
Rin raft Or Waffle slab at the most common type in New Zealand. Rib raft/Waffle slabs are a reinforced concrete footing and slab system constructed on ground. They consist of a perimeter footing (edge beam) and a series of narrow internal beams (strip footings) at one metre nominal centres running each way. The whole footing and slab system is constructed on top of the ground.
The sides of the slab are made by edged Formwork, and polystyrene blocks (pods) create the formed voids between the strip footings.
When viewed from underneath, the system of internal strip footings looks like a waffle – hence its called the Waffle Slab.
Strip footing
Strip footings are commonly found in load-bearing masonry construction, and act as a long strip that supports the weight of an entire wall. These are used where the building loads are carried by entire walls rather than isolated columns, such as in older buildings made of masonry.
Pile foundations
A pile is basically a long cylinder of a strong material such as concrete that is pushed into the ground so that structures can be supported on top of it.
Pile foundations are used in the following situations:
【1】
When there is a layer of weak soil at the surface. This layer cannot support the weight of the building, so the loads of the building have to bypass this layer and be transferred to the layer of stronger soil or rock that is below the weak layer.
【2】
When a building has very heavy, concentrated loads, such as in a high rise structure.
Pile foundations are capable of taking higher loads than spread footings.
There are two types of pile foundations, each of which works in its own way.
