The foundation is the base upon which the rest of the building shall rest; the foundation acts much like tyres in a car. Wobbly tyres cause instability in a car and can cause accidents; weak foundations cause buildings to collapse.
Unfortunately since foundations are hidden they tend to be taken casually sometimes with disastrous consequences.
Particularly for storied a building, you shall require a structural engineer to advice on design and supervise its construction.
Potential problems
Limited skills
Foundation laid on weak ground may cause building collapse
Badly mixed concrete
Poor design of foundation
Contact with ground water in areas with high water tables
Contact with soil with chemicals like sulphates
Materials, Plant labour requirements
Cement
Sand
Aggregate
Clean water
Reinforcement steel bars
Concrete mixer
Vibrator
Wheelbarrows
Form work
Masons and assistants
Carpenters and assistants
Procedure for site setting out
Transfer the building from the drawing to the site (called setting out by pros).
Excavate soil up to good hard surface level.
Spray sides and bottom of the excavations with a termite destroying solution.
If the sides are not stable enough have them protected from collapse.
If necessary lay formwork to sides of foundations.
Lay blinding (weak concrete or sand) to protect the concrete from coming into contact with soil.
Lay spacer blocks to protect steel coming into contact with soil
Lay steel as necessary
Lay well mixed concrete foundation. Vibrate concrete to drive out voids and to achieve consolidation.
The concrete mix hardens over time. This process needs to be slow. This is achieved by continuously wetting the foundation concrete over about a week.
After this, substructure walling can start. Same for concrete columns including form work and vertical steel members.
Once the substructure walls and columns reach the predetermined height then good practice calls for applying plaster on both sides of walls and after that applying water proofing to stop water movement through walls. After water proofing back filling of open trenches and pits should start. It is important to properly compact these open trenches failing which settlement results weakening the building.
At this point the building is ready to take the Ground Floor Slab which is our topic of discussion.
