Appraisal of Errors in Building Construction Due to Poor Workmanship

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Appraisal of Errors in Building Construction Due to Poor Workmanship

ABSTRACT

India, a country endowed with labor is experiencing an ironic situation. There is lot of unemployment due to lack of skills even though development is creating new employment opportunities. And most of the working labor is employed due to deficiency in supply of skilled workers. This paper aims to investigate errors occurring due to unskilled or low skilled workers in residential building constructions. Scope of the paper is limited till the construction of structure in residential low rise buildings. A survey is carried out to identify some of the common, yet important errors occurring in most of the residential constructions. Later a survey with structured questionnaire is carried out to find the factors responsible for these errors according to respondents. It is found that most of the errors occur because workers are haphazardly induced into this field without training. It can be concluded, if workers are trained, both delays and quality of project can be optimized.

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Keywords: Unskilled workers, Residential Constructions, Quality, Structure, Training

  1. ­Introduction

India is one of the world's fastest growing economies and this growth has brought with it a significant boost in construction activities (Roshan,2013).In India, construction industry is second largest economic activity after agriculture employing 33 million people accounting to 11% of GDP in India (Ramaswamy, 2010). Rapid infrastructure development in cities increase demand for workers in construction industry. Along with the demand there has been vast progress in development of new materials and techniques for construction process (Desai, 2001).But, residential constructions in India use labor-intensive manual techniques for construction. Even though designers are adapting to latest trends in design, construction techniques remained conventional in construction market. Very few projects are utilizing the latest technology available for construction. This results in spending more energy to construct modern buildings in traditional way. Using traditional skilled labor without technical expertise sometimes shows adverse effects on building throughout its lifecycle. To allow designers to transform the design concepts and ideas into good physical product, there should be quality labor capable to work with latest technology & materials. Due to availability of cheap labor, local contractors are employing manual techniques.

The quality of this skilled labor greatly affects both design and efficiency of the building. Over the past few years, a decline in the skilled workforce has caused delays, disruption and increased costs to all parties in the construction process. Many studies like National skill Development Corporation (, 2003) that surveyed statistics of workers support that the construction industry is facing a crisis of skilled workers shortages and training of its workforce is requires. For instance, industry is suffering shortage of construction workers for plumbing and machine operators, resulting in increase in project cost and slowing of construction activity (Heikkila, 2012).

  1. Problem Statement

The rapid growth of construction industry is affecting quality of construction. Major cause for low quality in buildings is an implication due to poor workmanship or low-quality of materials (Abdulrazak et al, 2010). Residences provide safe environment for us, universally it is accepted as essential for life sustenance and survival (Adenuga, 1999). Using the above statement, this research was carried out to examine the errors occurring in construction due to poor workmanship. Considering thigh usage of unskilled labor in residential constructions, survey is carried. It helped to understand the frequency of construction and to propose suitable solutions to the problem.

  1. Aim:

Aim of this paper is to investigate the errors occurring in construction and reasons of it.

  1. Research Questions:
  1. What are the errors occurring due to low skilled workers?
  2. What is the frequency of errors due to poor workmanship?
  3. Understand the level of responsibility of professionals in errors occurring
  4. What is possible solution to reduce errors?
  1. Research Methodology:

This research work considered errors occurring in residential buildings within Vijayawada, Andhra Pradesh, India.

  1. Questionnaire Design
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First, an extensive literature study was done in identifying errors occurring in construction due to unskilled workers and factors related to those errors. Then, three residential construction sites were selected for pilot study, which were under structural construction phase. Some of the errors were observed in these sites and documented for preparation of questionnaire. Unstructured discussions were also carried out with Architects and contractors to understand some more errors occurring in construction. Secondary research data from Afolarin, 2012 and Shittu, 2013 was also used to formulate questions. These listed errors are analyzed and then a structured questionnaire is prepared to research problem through survey. A survey was conducted by adopting five-point Likert scale for examining frequency of occurrence of errors in construction process. Respondents are requested to give value on a scale of 5, from least acceptance to highest acceptance.

Eg. How often do you observe these mistakes occurring in residential constructions in Vijayawada? On the scale of 5: 1. Never Happens/Not at all (strongly disagree) 2. Rarely happens (Disagree) 3. Neutral (happens, but occasionally) 4. Often happens/Agree (in most of the sites) 5. Happens always (happens in every project)

  1. Cleaning of sand is not carried out [ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ]
  2. Mixing percentage (cement : sand : gravel ) is compromised[ 1 ] [ 2 ] [ 3 ] [ 4 ] [ 5 ]
  1. Sample Size

The respondents were three architects and three building contractors with minimum 10-years of experience in respective fields. Due to time constraint, sample size is minimized to complete the paper. A complete questionnaire was handed over to them for response. Table 1 represents the distribution of respondents and their frequency.

Table1. Summary of the Respondents

Profession

Frequency

Architects

3

Contractors

3

  1. Analysis
    1. Frequency of defects in construction related to workers

Table 2: represents the respondents view about the frequency of occurrence of construction errors due to poor workmanship. The table shows that Leaks in shuttering, Inadequate Overlap of steel bars and improper shuttering levels are most commonly occurring errors in construction process. On the flipside, improper base for Scaffolding and not using spacers for columns is most rare error occurring.

Table 2: Response to frequency of errors in construction

Errors

Mean Value

Shuttering levels are checked manually

3.4

Inadequate overlap for reinforcement bar

3.4

Leaks in shuttering

3.4

Mixing percentage is compromised

3.2

Adding extra water to concrete

3.2

Watering columns manually

3.2

Spacers under reinforcement

3.2

Wrappers of pan and etc. are thrown

3.2

Cleaning of sand is not carried out

3

Vibration is done manually

3

Concrete spills

3

Time gap between mixing and usage

3

Minimum cover for columns is compromised

2.8

Formwork is not strong enough

2.8

Concrete is dropped from head level

2.75

Improper protection of slab from weather

2.4

Columns are casted without reference raiser

2.4

Spacers are not used for columns

2.2

Scaffolding rests on improper ground

2.2

Source: Field study, 2014

  1. Factors Causing Errors Related to Contractor

Table 3:

Table 3: Factors causing construction errors related to Contractors

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Factors

Mean

Consultants

Contractors

Improper supervision

4.67

5

4.33

Employing Unskilled workforce

4.71

4.75

4.66

Lack of experience to contractor

4.25

4.5

4

Changing skills requirements

4.00

4

4

Lack of knowledge about better techniques

3.71

3.75

3.66

Complicated roles of contractor

3.08

3.5

2.66

Unfamiliar construction equipment’s

3.33

4

2.66

Payment delays

4.17

4

4.33

Carrying multiple projects at a time

2.83

4

1.66

Limited profit

2.46

3.25

1.66

Limited time

2.33

3

1.66

Language barrier

1.25

1.5

1

Source: Field study, 2014

  1. Factors Causing Errors Related to Proffesionals

Table 4: represents the respondants ranking on five point scale for the factors causing construction errors which are related to proffesionals like architects and engineers.

Table 4: Factors causing construction errors related to Professionals

Factors’

mean

Consultants

Contractors

Inadequate Inspection quality

3.04

3.75

2.33

Not consulting professionals

2.42

2.5

2.33

Improper judgment of site conditions

2.79

3.25

2.33

Lack of agreement documents

2.42

2.5

2.33

Failing to prepare specification to all aspects of work

3.25

3.5

3

Delay in supply of drawings

3.04

3.75

2.33

Failure to inspect materials storage on site

2.08

2.5

1.67

Improper equipment specification

2.21

2.75

1.67

Mismatches in different drawings

2.25

2.5

2

Communication gap between site and office

3.46

4.25

2.67

Source: Field study, 2014

  1. Discussions
    1. Defects in Construction Process due to Poor Workmanship

Frequency of the errors occuring in construction according to the respondants is reprasented in Figure 1 bellow.

Figure 1:

Source: Field study, 2014 Major Errors Occurring Constructions due to poor workmanship

  1. Shuttering Levels Are Checked Manually

This is accepted as one of the most occurring errors in construction by majority of respondents. Scaffolding is finished two to three days before casting. Next, reinforcement workers throw reinforcement rods on scaffolding from heights. This causes improper settling of scaffolding. Also, reused wooden shutters are preferred in Vijayawada; improper joints cause lot of level differences in shuttering. But, as thread level is used to check levels from end to ends, the levels in between tend to be ignored. This also increases amount of concrete required to achieve proper sloping for water flow. By adopting latest construction technologies errors in shuttering can be reduced drastically.

  1. Inadequate Overlap For Reinforcement Bar

Overlap length is accepted to be mostly ignored error. It is either exceeds the required overlap or falls below the minimum required overlap length. Proper supervision on lower reinforcement joints is missing. This is mainly due to lack of education about scientific process of calculating overlap length according to the diameter of rod. This may cause a major defect in building and can even lead to failure of structure.

  1. Leaks In Shuttering

In Vijayawada, wooden scaffolding is cheaper than steel ones. So majority of the constructions are still opting wooden scaffolding. Because of poor quality wood used in shutters, there exists lot of gaps between joints. Improper joints allow cement to leak down and cement content in concrete mixture is compromised. Even in steel scaffoldings, when steel sheets are not joined properly same error is observed. But, comparatively using steel shutters have drastically reduced this error.

  1. Mixing Percentage Is Compromised

As most of the projects still use portable small scale concrete mixers, people add cement, sand, course aggregate and water manually using different sized vessels. So the thumb rule of weight ratio to volume of these vessels is not checked. Instead visual appeal is used as standard to check mix ratio. If the general notation of quantity is missed in particular batch people order workers to increase ratio for next batch. Sometimes laborers tend to miss one volume of any ingredients as each one is added by multiple people continuously. This is a major issue to be rectified, as it may even cause building failure.

  1. Adding extra water to concrete

Workers add extra water to concrete to increase slump to reduce efforts in placement. Possibility of adding one extra bucket of water is also there, because two to three people share the work of adding water to each batch of concrete mixing. This is normally observed immediately by site supervisor, but never any batch of concrete is rejected for this reason. Supervisor advices the laborers to reduce the water content, but does not send back the arrived quantities. It reduces the strength of concrete and also produces scaling of concrete.

  1. Watering columns manually

Curing is one of the most serious problems local to Vijayawada. But according to respondents, frequency of this error is varying greatly depending on the care taken by owner. Considering the hot climate of Vijayawada in summers, newly casted concrete has to be cured at greater rate. Unless concrete is cured at proper humidity and temperature, it will not attain desired strength. People pour water once or twice a day using hose pipe, but exterior temperature can vaporize the water content in minutes. So a proper continuous curing has to be done to attain desired strength. In extreme cases, improper curing can even cause structural cracking.

  1. Spacer blocks under reinforcement

After placement of reinforcement, people walk on it during casting. So, some blocks break before casting of concrete. This happens due to weak blocks or over load on blocks. In most of cases it is due to poor quality of blocks which are casted with improper concrete mixture. In some cases blocks are not cured properly due to delay in casting.

  1. Wrappers of pan and etc. are thrown

Most of the workers have a habit of smoking or chewing pan. They trash the wrappers during process of casting of concreting. When these wrappers are not taken care of, they cause “Bug holes” in concrete. Bug holes are small pockets of air or water, which cause leaks in slabs. If ignored, corrective measures have to be carried out to arrest leaks in slab.

  1. Cleaning of sand is not carried out

This is also one of the errors occurring in Vijayawada. Sand for construction is supplied from river bed after Prakasam Barrage. In rainy season, floods in River Krishna hinder the supply of sand. So, prior to rainy season, sand is stored in open lands without proper protection. During storage, due to natural forces leaves and biomass content is attracted to sand. When this biomass content increases 2%, it can cause major leaks and dampness in construction.

  1. Vibration is done manually

Most of the sites still use manual ways to consolidate concrete in columns. People use stick and/or shaking of reinforcement itself to consolidate concrete. When workers move reinforcement bars, the uneven placement of reinforcement may reduce the effective cover for steel bars. It also changes the alignment of the reinforcement. This may lead to corrosion of the reinforcement and gradually decreased strength in columns.

  1. Concrete spills

During concreting, concrete is carried from ground level to slab level by concrete lifting hoist. After it is poured on slab, workers manually carry it to all parts of slab. While carrying the concrete to all points, small concrete spills are observed. This concrete spills undergo setting before actual concreting is done in particular place. This may cause cracks due to uneven expansions in this heterogeneous mixture.

  1. Time gap between mixing and usage

This is opted as one of the least occurring error. In rare cases, workers mix concrete in large amounts before lunch break. This time gap between mixing and usage of concrete reduces the strength because water allows cement to react and start hardening. People are conscious about the ill effects of delay in usage.

  1. Minimum cover for columns is compromised

After survey, it is observed to be similar with question “j”.

  1. Formwork is not strong enough

Most of the residences use wooden formwork for slabs. This is because of the economic feasibility to the client. The joints are not designed and it is done by unskilled workers. So, during casting formwork collapses or sinks causing threat to workers. And also if the base sinks little bit, that much extra concrete is required to be poured to achieve desired slope.

  1. Concrete is dropped from head level

When concrete is dropped from height, heavy course aggregate tends to settle but loose cement mixture tends to slide out. This causes improper mix ratio in the concrete. But, after survey it is found to be not so big problem.

  1. Improper protection of slab from weather

In rainy season newly casted slab has to be protected from possible weather effects. If the newly casted slab is left open to rains, it creates settling of subgrade due to extra water content in top layers.

  1. Columns are casted without reference raiser

It is considered as one of the least occurring errors in constructions.

  1. Scaffolding rests on improper ground

In most of the residential constructions, plinth of nearly one-meter is observed. Fly-ash or sand is used as filling material for raising plinth level, because they are cheaply available in Vijayawada market. Scaffolding work is started before strong hardening of plinth filling and vertical members rest on plinth-filling. As bearing capacity of newly filled soil is low, it allows sinking of supports.

  1. Factors causing building errors related to contractor

Results of contractor & worker related errors

  1. Results of Consultant related errors

  1. Results of General Questions

From the whole exercise, it is understood that construction errors occur due to various factors, but most of them related to human factors. It is understood from the mixed results for similar questions that there is vast variation in skills in workers.

  1. CONCLUSION Feasible solution/Proposal for improvement in skills of construction workers

It can be proposed from the whole analyses that a training institute can increase the quality of works happening in Vijayawada.

Biblography

1. Shetty, R.S., 2013. Construction and Demolition waste – An Overview of Construction Industry in India. International Journal of Chemical, Environmental & Biological Sciences (IJCEBS), 4(2013), pp.4–6.

2. Heikkila, P. (2012) ‘India Inc runs dry of skilled workers’, The National, 1 January.

3. Desai, U.C., 2001. Low-cost housing : Common mistakes in construction. The Indian Concrete Journal, (January).

4. (Abdulrazak et al[11], 2010) - B. I. Abdul Razak, H. R. Matthew, Z. Ahmed and I. Ghaffar, An investigation of the status of the Malaysian construction industry, Benchmarking: An International Journal, 17(2), 2010, 294-308.

5. Shittu, A., Adamu, A. & Mohammed, A., 2010. Appraisal of Building Defects Due To Poor Workmanship In Public Building Projects In Minna, Nigeria. iosrjen.org, 9(2005), pp.30–38. Available at: http://www.iosrjen.org/Papers/vol3_issue9 (part-3)/E03933038.pdf [Accessed October 29, 2014].

6. Adenuga, O.A., 2012. Professionals In The Built Environment And The Incidence Of Building Collapse In Nigeria. Organization, Technology and Management in Construction: An International Journal, 4(2), pp.461–473. Available at: http://www.grad.hr/otmcj/clanci/vol4_is2/OTMC_2.pdf [Accessed October 29, 2014].

  1. H. Abdul Rahman, M. A. Berawi, A. R. Berawi, O. Mohamed, M. Othman and I. A. Yahya, Delay mitigation in the Malaysian construction industry, Journal of Construction Engineering and Management, 132(2), 2006, 125-133

i. Project management

ii. Subcontractor

iii. Lack experience in labors

iv. Language barrier in communication

v. Unsuitable construction equipment’s

vi. Poor weather condition

vii. Limited time

viii. Limited cost

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