After detailed planning and designing of construction work by the architect and structural designer, the next step to start actual construction work on site.
Generally, most of the construction work begins with foundation construction. Foundation construction is the most critical work among all activities on the construction sites. Foundation is the main base and support for all the above structures.
Foundation construction is a crucial stage as the dimensions of the foundation have to be entirely right because otherwise, the future spaces will be affected. The depth of foundation depends on the type of soil, and the site conditions decide the design of the foundation.
The foundation layout and excavation depth details are prepared by the structural designer and approved by the Architect.
What is Foundation?
Foundation is the bottom-most part of any structure, which has the primary function is to take load coming from upper components and safely transfer it to the below soil. Generally, foundations are of two types, namely shallow foundation, and deep foundation.
A shallow foundation is constructed for a structure that has a horizontal spread more than vertical height. A deep foundation is most suitable for high-rise buildings like a skyscraper or a castle built on very weak. If any structure is to be extended vertically in the future, then a deep foundation must be suggested.
Width of Foundation/Footing
Structural Design is the main component to consider before laying Foundation/Footing. For small buildings such as houses, flats, school buildings, etc not having have not more than two storeys, the width of the foundation should be as given below,
- For one brick thick wall, the footing should not be less than 75 cm in width.
- It should not be less than 1 meter in terms of width for one and a half brick wall.
The Function of Foundation
- Foundation provides the main base for any structure.
- It provides stability and strength to the main building structure.
- Foundation provides a level surface for the construction of substructure.
- It distributes the structural load evenly into the ground.
- Foundation reduces the load intensity within the safe bearing capacity of the soil.
- It safe the soil movement effect is resisted and prevented.
Read More: 15+ Types Of Drawings In Construction
Foundation Construction Steps
Following are the steps in foundation construction,
1. Foundation Layout
The Contractor has to follow the foundation layout drawing for excavation prepared by the structural designer and approved by the Architect. As per the foundation layout plan marking is done on-site, and the Architect cross-checks the dimensions.
Foundation marking should give extreme importance. If there is any mistake can b brought to the Architect’s and contractor notice, So that they quick action to rectify the error.
Once the final foundation layout marking has approved, the excavation can begin. Start excavation work and continuously check the work process. Never excavate soil beyond the depth specified by the architect in the drawing.
In chase deep foundation like pile foundation, the depth of foundation not specified, but it is up to hard strata is given. As excavation work progress, check if there is a requirement of providing support to a soil against collapse.
3. Filled up Soil
If construction is to be done on lakes or low-lying areas, it may have a lot of filled up soil. In such type of filled up ground excavation must be done till the firm ground is reached. This will obviously increase the depth of foundation and consequently, the cost of the foundation will be very high. But, Never compromise on this.
Always make sure that building foundation resting on hard strata if it means you have to go 15 feet down because otherwise, it will affect the stability and strength of the house.
4. Excavation Trenches/Pits
The excavation details depend on the construction method that you have decided to adopt, the load-bearing-wall system, or the column-beam-frame structure system.
In the case of a load-bearing structure, trenches are excavated along the wall. If it is framed structure, then excavation is done below every column up to the footing base. All work should be done as per drawings and instructions are given by architects and structural designers.
Read More: What Is The Strongest Foundation For A House
5. Anti-termite Treatment
Before starting foundation construction, make sure that the trenches and excavated areas have been given the anti-termite treatment by the Contractor. This anti-termite treatment ensures protection against termites and other pests from underground, in the future
6. Foundation Construction
Once Excavation work is done for foundation, the next step is to Start the foundation construction.
- Load bearing structure foundation: A bed of concrete (PCC) is laid at the base of trenches and over it, the brick or stone masonry is constructed in accordance with the foundation details provided by the structural designer.
- Column-beam frame structure system: In this system column footing is constructed in the trench. There are different types of footing used in building construction like spread footing, pad footing, Trapezoidal column footing, Mat foundation, etc.
- In this case of isolated pad footing, steel bars tied together according to the structural engineer’s specifications are placed at the bottom of the footing pit. Column steel bars are also tied in place with the help of a bonding wire. Column formworks are erected around it for pouring concrete.
- Pouring concrete: Before pouring concrete in the formwork architect and structural designer have approved the steel details and the quality of work, the concrete can be poured. Concrete for pouring can prepare on-site or the contractor may opt for ready mix concrete (RMC) if there are very large footings and large requirements of concrete.
- Plinth Beam: After the column is constructed up to the Plinth beam level, the plinth beam is erected for the walls of the house to rest on.
7. Curing of Foundation
Immediate curing of concrete components is an essential task on any construction site. If the Curing of concrete is not done properly, cracks can appear and even the strength and life of the building components can be affected. Curing ensures sufficient water is available for the chemical reaction which provides strength to concrete.
The chemical reaction during curing: There are two types of chemical reaction that take place in concrete one that releases heat during the process (Exothermic) and another that absorbs heat (Endothermic).
The process of mixing cement with water is an exothermic reaction due to the presence of limestone. Because of this heat production, the water in the mortar or concrete mix evaporates even before the compound gains strength.
For a structure to achieve maximum strength the chemical reactions in cement compound must go on and this can happen only in the presence of water and at ambient temperature. Hence, it is required to supply extra water content and the ambient temperature and this is achieved by regular curing.
It is important in any foundation construction to start curing process as early as possible.
8. Starting the Curing Process
Curing should always start to the very next day after the concrete has been poured. In the earlier stages, concrete elements absorb water more, but after a week, the water required will be much less.
In case there is excessive water runoff on a concrete surface, when water is poured on new construction, curing should be stopped. As the outside temperatures are higher the more amount of curing is required.
Curing schedule: Concrete element curing should be done at least twice a day through three times is better. Ensure that you’re Contractor given this job to a specified person so that it is not forgotten.
Requirement of Good Foundation
Good Foundation is need of a structure because of following reasons,
- Foundation form the base of any Structure, the whole stability of the structure is dependent on the foundation. Even a minor error might take a destructive form. Hence a good foundation with precise construction is recommended.
- The structure might undergo settlement during its life span. Settlement of Structure is defendant on the Foundation, such that a good foundation can avoid a differential settlement.
- A good foundation can guard any form of damage or distress transfering the load evenly to soil.
- Care is taken that the site for laying foundation must not undergo any stress or affected because of future works in surrounding.
- One of the requirement of Good Foundation is that it should be capable of transmiting dead as well as live load to the soil beneath.
What is the Purpose of The Foundation?
Any Foundation of Structure serves the following Purposes,
- Stability to a structure is provided by the means of foundation. A good and sound foundation ensures the better stability of the structure.
- Foundation is meant to transfer the dead as well as live load efficiently to the soil.
- Foundation laid in proper manner provides a reliable base for the further construction of the substructure as well as superstructure.
- Foundations maintain the stability of the structure during natural calamities such as earthquakes and floods and protect it from collapsing.
- Differential settlement of structure can be avoided which might cause the tilting of structure.
FAQs: Foundation Construction
Steps in Foundation Construction
Filled up Soil
Curing of Foundation
Starting the Curing Process
Foundation Construction Process
Foundation marking on ground
Excavation of foundation
Filled up Soil
Anti-termite Treatment to ground
Formwork and steel placement
Concreting in footing
Curing of Foundation
House Foundation Construction Steps
following are house foundation construction steps,
1. layout of the column
2. Marking of the footing trench
3. Excavation of foundation trenches
4. Leveling the foundation base
5. PCC work in the foundation
6. Footing formwork and concreting work
7. Curing of Footing
8. Removal of formwork
9. Backfilling the trenches
10. Starting the above-ground construction
You May Also Like:
- Raft Foundation (Mat Foundation) | Types & Advantages
- Caisson Foundation – Its Types & Application
- 25+ Types of Pile Foundations & Their Application
- Floating Foundation – Principles, Construction Steps