In continuation to my previous article on, ‘Tips for Individual House Construction’ this article explores the role and importance of Structural Engineer in Individual House Construction.
A qualified and experienced Structural Engineer (SE) plays a very important and valuable role in structural design, even if it is a simple single storyed house.
Unfortunately, even today few well-educated potential house owners do not realize a SE’s role.
As I walk along the streets observing simple residences under construction, I observe that most of the structures are over designed and in a few cases grossly under designed.On casual enquiry, I was given to understand the owner has given the complete responsibility of construction of the building to an ‘experienced’ contractor who neither has any professional credentials nor has the contractor hired a person with professional qualifications to design and supervise construction.
The structural design, in these cases, seems to be based on ‘factor of ignorance’rather than ‘factor of safety’
It is very unfortunate that we follow lot of rules and regulations to have a house plan sanctioned by authorities, the same authorities have not made it a cognisable offense to have a structure constructed without the assistance of a professional structural engineer (In a pharmacy, one must have, at least by law, a qualified pharmacist to dispense prescribed medicine).
Let us list out the reasons why a SE is required.
Foundation design depends on various parameters, however, for a simple structure predominantly depends on:
- Type of soil.
- Load the foundations have to carry.
Based on the above factors, size, shape, type of foundation and materials for construction is arrived at.Therefore, it would be a very expensive mistake leading to potential danger to both life and property to adopt a foundation design that is not specific to the particular location and configuration of the house under consideration.Similarly, the superstructure has to be designed considering various factors and is specific to each building.
A SE will not only design a safe structure (as per the Bureau of Indian standards), which is durable and economical, SE will bring add value during the design stage in co-ordination with the Architect.
Let me give a few examples where the design has gone awry because the owner tried to save money by NOT engaging the services of a qualified SE.
- Settlement of foundations since the soil characteristics were not studied.
- Drooping cantilever slabs. Wrongly placed re-inforcement.
- Heavy foundations and a framed structure for a simple single storyed building.
- Cracks along the bottom of very steep sloping slabs.
- Collapse of slabs since the same reinforcement design was used progressively increased spans, even though the original design was meant for a particular span.
- Progressively decreased beam reinforcement for the same spans at higher levels (same principal of reducing the column reinforcement for higher levels, was adopted for the beams also since the contractor thought he is saving money).
Do:
- Engage services of a SE without fail.
- You may directly appoint structural engineer or the Architect may appoint the SE.
- Bring SE on board at the concept stage.
- Request SE to inspect the site.
- Have few exploratory pits dug to examine the characteristics of soil to ascertain its load carrying capacity.
- Check if the subsoil water table is high with respect to the foundation level.
Do not:
- Select the cheapest SE based on kgs/sft of steel design. One can save steel by NOT adhering to the requirement of the BIS codes.
- Compromise safety and durability by delegating the responsibility of ‘design’ to unqualified persons.
- Underestimate the importance of the role of a structural engineer.