It is a known fact that not everyone that invests in the Construction industry knows so much about the construction job.This article assists you from being a novice when your Engineer carries out his activities on your project.After the documentation, in which procedures vary from one locality/region to another, the next thing to be done is to complete the sub structure(foundation) which includes:
1.Site Clearing
Only on rare occasions would any piece land be without trees,bushes, grasses etc. Even in some instances a building might have existed on the land and demolished. The trees must be felled and roots grubbed up, bushes and grasses cleared or rubble from the demolished pre-existing building cleared up. All these activities are carried out to ensure a proper and healthy working environment. Removal of top soil is also necessary in situations where the land had bushes and grasses. This is done to a depth of about 150mm (approximately 6 inches). The soil is assumed to be weak and has vegetative materials,also serves as habitat to some micro organism which are not healthy for the foundation of a building.
2.Excavation
The depth of the excavation is determined by a structural engineer who considers the soil, the frostline(the maximum depth at which soil is frozen) and the height of the water table (the depth in the soil at which you find water). The excavation must be deep enough to place the top of the footing below the frost line. This prevents the concrete from cracking due to the freeze-thaw cycle of the surrounding soil(common in areas with cold climate). The excavation should not be so deep that it would below the water table, because that can cause a chronically wet or flooding to foundation.
3. Footings and Concrete Blinding
Footings are concrete bases that help to spread the weight of the structure from the foundation walls or columns to the surrounding soil. Footings are wider than the foundation walls/columns they support, and form the perimeter of the structure. Sometimes, additional footings are added inside the perimeter to support load-bearing interior walls.Concrete blinding is the process of pouring a thin layer of concrete over the floor of a new building; this can be over the hardcore or over the foundation itself. The purpose of this is to seal in underlying material and prevent dirt and mud from interfering with the structure.
4 Walls
Foundation wall thickness is determined by a structural engineer who considers the height of the wall and the load it will be able to carry conveniently. (Structural load is the force or combination of forces of gravity, wind, and earth that act on the structural system of a building). Wall thickness varies from structure to structure, and even within a building
5 Filling, Backfill and Hardcore
Filling the foundation is another important aspect that requires adequate attention as the materials to be used to fill the foundation will depend on the condition of the site with is to be determined by a professional. While backfilling is pushing into the trenches the materials that was excavated from the foundation,it is recommended that it should be soil that drains easily. Apart from burying a portion or all of the walls below the surface,it also provides ideal stability needed by the foundation. After the foundation has been filled reasonably and well compacted, hardcore (sizes between 75mm and 300mm) are placed and compacted.
6 Dampproofing and Waterproofing
Dampproofing and waterproofing are usually mistaken for each other but they literally mean different things(read more in the article 'Dampness in Building and its Prevention'). A damp proof course is a course of some impermeable material laid in the foundation walls of building near the ground to prevent dampness from rising into the building. It is a horizontal barrier in a wall designed to prevent moisture rising through the structure by capillary action.
7. Concrete Reinforcement-Wire Mesh
This is placed strategically to ensure that there's no continuous cracking of concrete slab. It is also referred to as thermal reinforcement
8. Oversite Concrete (german floor)
This is a 4-inch to 6-inch thick concrete carefully placed and in a mixing ratio that will be specified by the Engineer.
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