Comprehensive maintainability scoring system (COMASS) for commercial buidings in tropical climate of singapore 1

COMPREHENSIVE MAINTAINABILITY SCORING
SYSTEM (COMASS) FOR COMMERCIAL BUILDINGS IN
TROPICAL CLIMATE OF SINGAPORE











SUTAPA DAS

NATIONAL UNIVERSITY OF SINGAPORE
2008

COMPREHENSIVE MAINTAINABILITY SCORING
SYSTEM (COMASS) FOR COMMERCIAL BUILDINGS IN
TROPICAL CLIMATE OF SINGAPORE











SUTAPA DAS
(B.Arch. (Hons.), JU; M.Tech, IIT Madras)

A THESIS SUBMITTED
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY
DEPARTMENT OF BUILDING
NATIONAL UNIVERSITY OF SINGAPORE
2008
ACKNOWLEDGEMENTS

This thesis is dedicated to my husband Abhijit Chaudhuri for his unconditional love, sacrifice
and patience.

COMASS is an outcome of persistent effort and a great deal of commitment. It has drawn
intellectual support and generous help from experts from various fields. The list is endless and
also the contributions. It is like a beautiful pearl string where each pearl is equally precious
and unique. I take this opportunity to express my sincere thanks to everyone, who has been
with me in this ‘Immense journey in search of excellence’.

First of all I would like to specially mention about my supervisor and mentor Prof. Michael
Yit Lin Chew; my thesis committee members Dr. Wong Nyuk Hien and Dr. Evelyne Teo.
Without them nothing was possible. Dr. Poh Kim Leng from Dept of Systems & Industrial
Engineering provided an extraordinary guidance in a critical part of this research.

I am deeply indebted to the following treasured personalities for their help in one way or other:
● Ms. Nayanthara De Silva (University of Moratowa).
● Dr. Kang Kok Hin (Institute of Facilities Management).
● Other professors and staffs of Dept. of Building, National University of Singapore.
● Industry experts from several prestigious facility management organizations.
● My students: Adeline, Fong Yee, Hoe Kiat, Nur Hafizah, Tsz Shan and Wen Tirng.
● My colleagues: Benson, Bin, Jovan, Shams, Swei Mei and many others.

I pay my gratitude to my family members - my husband, mom and mom-in-law for providing

uncompromising moral strength to sail through all ups and downs. The last but not the least
mention is my late father – whom I could not even bid a farewell. He wanted me to fulfil my
academic responsibility and silently left his blessings.

i
SUMMARY

Growing complexity of building systems and higher user requirements have prioritized
maintainability over maintenance especially for commercial building sector in order to attract
and retain clients. A thorough literature review indicated that unlike sustainability, there is no
comprehensive maintainability scoring system (COMASS) to predict maintainability potential
of buildings. In spite of good design-construction-maintenance guidelines, recurrent defects
keep buildings under constant maintenance, putting users’ health and safety at stake apart
from affecting economy and system performance. This paradox has been attributed to dearth
of: (1) knowledge database of defects; (2) system selection framework and (3) communication.

Proposed COMASS addresses this knowledge gap. It is a decision-enhancement tool aimed
for part or whole of a new or existing building for selecting the best strategy to ‘design out’
defects. Research objectives was set as 3 deliverables: (1) Defect Library (DL) to improve the
knowledge on building defects; (2) Maintainability Handbook to benchmark design-
construction-maintenance practices along with maintainability score (MS); and (3) integration
of building elements and life cycle phases into COMASS

Commercial buildings of Singapore for its key elements under central facility management
were studied. Qualitative FMECA (Failure Mode Effects and Criticality Analysis) was
selected for defect grading. Building was divided into nine major subsystems grouped into
two main systems: (1) civil-architectural or C&A (basement, facade, wet-area and roof) and
(2) mechanical-electrical or M&E (sanitary-plumbing, HVAC, elevator, electrical and fire-
protection). From 14 detailed case studies and interview with 34 facility managers (FM), 319
defects pertaining to 62 major components of these subsystems were identified. Their causes

were analyzed in terms of (1) design/ specification; (2) construction/ installation; (3)
maintenance; and (4) external factors. About 45.5% defects were found critical based on their
frequency and severity (impacts on economy, system performance and health-safety-comfort).

ii
Maintainability guidelines comprised of 731 defect-mitigating checklist factors was
developed from literature and DL. They were grouped into life-cycle phases and further
subgrouped under components of subsystem. Factors’ relative weights (RW) are their ability
to mitigate both critical and non-critical defects. Weighted sum of the MS of each factor
indicates MS for individual sub-system, where a higher score means higher maintainability.

For integration of subsystems into COMASS w.r.t both objective and subjective parameters,
AHP (analytic hierarchy process) using interview and questionnaire was critically selected.
Eleven consistent results were used to determine 12 sets of RWs for 9 subsystems for various
location-height combinations. Seamless matching of objective result with experts’ subjective
opinion proved the integration process logical and comprehensive. Predictive accuracy of
COMASS was found satisfactory through operational validity and sensitivity test via Monte
Carlo simulation. A prototype multi-tenant office tower at CBD was modelled.

COMASS is the first attempt in building maintainability for holistic integration of phases of
building lifecycles and components. From existing defects, COMASS evaluated the entire
decision making process of building life cycle and reflected back the same on performance.
Hence COMASS was able to bridge the knowledge gap between theoretical guidelines and
their real life implication. This research further highlighted that performance, not cost was the
main governing factor in facility management. The standard of performance based on both
objective and subjective parameters imposes different emphasis of different building
components. This decision–enhancement tool empowered with a user friendly, performance
based online version (
www.hpbc.bdg.nus.edu.sg) aspires to improve the quality of building
industry significantly. The generic method is applicable to other building types and climates.

Further refinement with real-life testing, consideration of chain effect of defects to the fullest
extent and time-dependent decision making were identified as the scope of future research.

Keywords: AHP, Benchmarking, Defects, FMECA, Maintainability, Scoring system.

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TABLE OF CONTENTS

Acknowledgements ………………………………………………………………… i
Summary ………………………………………………………………… ii
Table of Contents ………………………………………………………………… iv
List of Tables ………………………………………………………………… ix
List of Figures ……………………………………………………………………… xiv
List of Acronyms …………………………………………………………………… xvii

CHAPTER 1 INTRODUCTION ……………………………………………… 1

1.1 Background …………………………………………………………………… 1
1.1.1 The concept of maintainability and maintenance …………………. 1
1.12 Significance of maintainability ……………………………………. 2
1.1.3 Research problem – A paradoxical situation in Singapore………… 2
1.1.4 Rationale of the study ……………………………………………… 4
1.1.4.1 Dearth of knowledge database of defect ……………… 4
1.1.4.2 Dearth of system selection framework ………………… 5
1.1.4.3 Lack of communication ………………………………… 6
1.2 Research guideline …………………………………………………………… 6
1.2.1 Knowledge gap ………………………………………………….… 7
1.2.2 Aim and Objectives ……………………………………………… 7
1.2.3 Hypothesis …………………………………………………………. 7
1.2.4 Scope of Research …………………………………………………. 7

1.2.5 Knowledge Contribution ………………………………………… 9
1.2.6 Practical Implication ………………………………………………. 9
1.3 Definition of terms ……………………………………………………………. 10
1.4 Organisation of the thesis …………………………………………………… 10
1.5 Summary ……………………………………………………………………… 12


CHAPTER 2 LITERATURE REVIEW ……………………………………… 13

2.1 Introduction …………………………………………………………………… 13
2.2 Building components in terms of maintainability ……………………………. 14
2.3 Building maintenance ………………………………………………………… 16
2.3.1 Objectives of maintenance ………………………………………… 16
2.3.2 Decision support frameworks in maintenance ……………… …… 17
2.4 Maintainability ……………………………………………………………… 21
2.4.1 Objectives of maintainability ……………………………………… 21
2.4.2 Maintainability in building research ………………………………. 21
2.5 Maintainability tools in system engineering ………………………………… 23
2.5.1 Fault Tree Analysis (FTA) ………………………………………… 23
2.5.2 Fishbone Diagram …………………………………………… … 24
2.5.3 Failure Mode Effect and Criticality Analysis (FMECA) ………… 24
2.5.4 FMECA in building sector ……………………………………… 27
2.6 Existing building grading systems ……………………………………………. 28
2.6.1 Classification of grading system ………………………………… 28
2.6.1.1 First generation: pass-fail ………………………………. 30

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2.6.1.2 Second generation: simple additive ……………………. 30
2.6.1.3 Third generation: weighed additive ……………………. 30
2.6.1.3 Others ………………………………………………… 32

2.7 Principles for weighing and aggregation of multiple parameters …………… 34
2.7.1 Equal weight ……………………………………………………… 35
2.7.2 Weights based on statistical models ……………………………… 35
2.7.3 Weights based on opinions: MCDA methods …………………… 36
2.7.4 Comparisons of the methods ……………………………………… 39
2.8 Knowledge gap ……………………………………………………………… 40
2.9 Summary ……………………………………………………………………… 41


CHAPTER 3 RESEARCH METHODOLOGY ……………………………… 42

3.1 Introduction …………………………………………………………………… 42
3.1.1 Brief overview of research methodology ………………………… 42
3.2 Phase 1: Conception ………………………………………………………… 42
3.3 Phase 2: Individual maintainability scoring ………………………………… 44
3.3.1 Selection of defect grading strategy ……………………………… 44
3.3.2 Development of criticality parameters …………………………… 45
3.3.3 Selection of respondent and sampling frame ……………………… 46
3.3.4 Site Investigation ……………………………………… 47
3.3.5 Questionnaire design and pilot survey …………………………… 48
3.3.6 Main survey ……………………………………… 49
3.3.7 Proposed Defect Library (cause and criticality analysis) ………… 50
3.3.8 Maintainability Handbook and subsystem grading ……………… 51
3.4 Phase 3: Integration of building subsystems into COMASS …………………. 52
3.4.1 Selection of AHP as suitable technique for integration …………… 53
3.4.2 Construction of hierarchy ……………………………………… 55
3.4.2.1 Goal ……………………………………… 55
3.4.2.2 Criteria ……………………………………… 56
3.4.2.3 Sub-criteria under location …………………………… 56
3.4.2.4 Sub-criteria under height ……………………………… 57

3.4.2.5 Mutual exclusiveness of sub-criteria …………………… 57
3.4.2.6 Alternatives ……………………………………… 57
3.4.3 Development of questionnaire …………………………………… 58
3.4.4 Selection of respondents and sample size …………………………. 60
3.4.5 Data collection – survey & interview ……………………………… 60
3.4.6 Data analysis and global weight (GW) calculation ……………… 61
3.4.6.1 Inconsistency ratio …………………………………… 61
3.4.6.2 Aggregation of results ………………………………… 62
3.4.6.3 Derivation of global weights from local weights ………. 62
3.4.7 Development of COMASS ……………………………………… 63
3.5 Phase 4: Conclusion ……………………………………… 64
3.5.1 Checking the predictive accuracy …………………………………. 64
3.5.1.1 Validation ……………………………………… 64
3.5.1.2 Sensitivity analysis …………………………………… 66
3.5.1.3 The proposed testing method for COMASS …………… 66
3.5.2 Practical application ……………………………………… 67
3.5.3 Conclusion and recommendation ………………………………… 67
3.6 Summary ……………………………………… 67






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CHAPTER 4 DEFECT ANALYSIS …………………………………… 68

4.1 Introduction …………………………………………………………………… 68
4.2 General findings of questionnaire survey …………………………………… 68
4.2.1 Demographic information ………………………………………….

68
4.2.2 Significance of grading criteria and building subsystems …………. 70
4.2.3 Format of defect reporting ………………………………………… 70
4.3 Defects in basement ………………………………………………………… 71
4.3.1 Criticality analysis of defects in basement ………………………… 74
4.4 Defects in facade ……………………………………………………………… 75
4.4.1 Criticality analysis of defects in facade …………………………… 83
4.5 Defects in wet area ……………………………………………………………. 85
4.5.1 Criticality analysis of wet area defects …………………………… 89
4.6 Defects in roof ………………………………………………………………… 89
4.6.1 Criticality analysis of defects in roof ……………………………… 94
4.7 Defects in sanitary-plumbing system …………………………………………. 95
4.7.1 Criticality analysis of defects in sanitary-plumbing system ………. 101
4.8 Defects in HVAC system …………………………………………………… 102
4.8.1 Criticality analysis of defects in HVAC system ………………… 107
4.9 Defects in elevators (or lifts) ………………………………………………… 108
4.9.1 Criticality analysis of defects in elevators ………………………… 114
4.10 Defects in electrical system …………………………………………………… 116
4.10.1 Criticality analysis of defects in electrical system ………………… 122
4.11 Defects in fire protection system ……………………………………………… 123
4.11.1 Criticality analysis of defects in fire protection system …………… 128
4.12 Comparison of causes and criticality of building subsystems ……………… 129
4.13 Summary …………………………………………………………………… 131


CHAPTER 5 MAINTAINABILITY SCORING FOR BLDG. SUBSYSTEMS 132

5.1 Introduction …………………………………………………………………… 132
5.2 General format of maintainability scoring ……………………………… 132
5.2.1 Mathematical principle …………………………………………… 132

5.2.2 Maintainability Handbook ………………………………………… 133
5.3 Maintainability scoring for basement …………………………………… … 133
5.4 Maintainability scoring for facade …………………………………………… 135
5.5 Maintainability scoring for wet area ………………………………………… 137
5.6 Maintainability scoring for roof ………………………………………………. 139
5.7 Maintainability scoring for sanitary-plumbing system ……………………… 141
5.8 Maintainability scoring for HVAC system.………………………………… 144
5.9 Maintainability scoring for elevators …………………………………………. 146
5.10 Maintainability scoring for electrical system …………………………………. 149
5.11 Maintainability scoring for fire protection system ……………………………. 152
5.12 Overview of scoring of all subsystems ……………………………………… 154
5.13 Summary …………………………………………………………………… 154


CHAPTER 6 COMPREHENSIVE MAINTAINABILITY SCORING SYSTEM 155

6.1 Introduction …………………………………………………………………… 155
6.2 Data analysis ………………………………………………………………… 155
6.2.1 Data processing in ExpertChoice (EC 11.5) ………………………. 155
6.2.2 Dealing with inconsistency ……………………………………… 157
6.2.3 Selection of threshold limit of IR and the best dataset …………… 158

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6.2.3.1 Preliminary test result …………………………… …… 159
6.2.3.2 Statistical test result …………………………………… 159
6.2.3.3 Rank reversal …………………………………………… 160
6.2.3.4 Selection between Dataset 1 and 4 …………………… 160
6.2.4 Derivation of GW from LW ……………………………………… 161
6.3 Results and discussion ………………………………………………………… 163
6.3.1 Influence of criteria: location and height ………………………… 163

6.3.2 Influence of sub-criteria: location …………………………………. 163
6.3.3 Influence of sub-criteria: height …………………………………… 165
6.3.4 Relative importance of C&A and M&E systems………………… 166
6.3.4.1 Influence of location on C&A and M&E systems……… 166
6.3.4.2 Influence of height on C&A and M&E systems ……… 167
6.3.5 Relative importance of all nine subsystems ……………………… 168
6.3.5.1 Rank 1: HVAC system …………………………………. 170
6.3.5.2 Rank 2: Elevator system ……………………………… 170
6.3.5.3 Rank 3: Facade …………………………………………. 171
6.4 Application of GW in COMASS …………………………………………… 171
6.4.1 Example of a calculation in COMASS ……………………………. 171
6.5 Summary …………………………………………………………………… 172


CHAPTER 7 TESTING AND APPLICATION ………………………………
173

7.1 Introduction …………………………………………………………………… 173
7.2 Operational validity …………………………………………………………… 173
7.2.1 Details and specification of the prototype building ……………… 173
7.2.2 Scoring for basement ……………………………………………… 174
7.2.3 Scoring for facade …………………………………………………. 176
7.2.4 Scoring for wet area ………………………………………………. 178
7.2.5 Scoring for roof …………………………………………………… 180
7.2.6 Scoring for sanitary-plumbing system ……………………………. 182
7.2.7 Scoring for HVAC system ………………………………………… 185
7.2.8 Scoring for elevators ………………………………………………. 187
7.2.9 Scoring for electrical system ………………………………………. 189
7.2.10 Scoring for fire protection system …………………………………. 192
7.2.11 Scoring for entire building ………………………………………… 195

7.3 Sensitivity analysis via Monte Carlo simulation ……………………………… 196
7.4 Web based application of COMASS ………………………………………… 197
7.4.1 Defect Library …………………………………………………… 197
7.4.2 Maintainability Scoring System …………………………………… 198
7.5 Summary …………………………………………………………………… 200


CHAPTER 8 CONCLUSIONS …………………………………………………. 201

8.1 Introduction …………………………………………………………………… 201
8.2 Research summary showing achievement of research goal…………………… 201
8.3 Key findings ………………………………………………………………… 203
8.4 Knowledge contribution ………………………………………………………. 205
8.5 Industry contribution ………………………………………………………… 207
8.6 Limitation of the study ……………………………………………………… 208
8.7 Scope for future research …………………………………………………… 208
8.8 Concluding remarks ………………………………………………………… 209



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BIBLIOGRAPHY ………………………………………………………………… 210


APPENDIXES ………………………………………………………………… 240

Appendix A Survey questionnaires …………………………………………… 240
Appendix B Results of defect rating survey …………………………………… 251
Appendix C1 Maintainability guidelines for basement ………………………… 275
Appendix C2 Maintainability guidelines for facade ……………………………… 288

Appendix C3 Maintainability guidelines for wet area …………………………… 307
Appendix C4 Maintainability guidelines for roof ……………………………… 319
Appendix C5 Maintainability guidelines for sanitary-plumbing system …………. 331
Appendix C6 Maintainability guidelines for HVAC system …………………… 347
Appendix C7 Maintainability guidelines for elevators …………………………… 358
Appendix C8 Maintainability guidelines for electrical system ………………… 371
Appendix C9 Maintainability guidelines for fire-protection system …………… 390
Appendix D AHP survey results ………………………………………………… 404
Appendix E Results of sensitivity test by Monte Carlo simulation …………… 410


LIST OF PUBLICATIONS ………………………………………………………… 414



viii
LIST OF TABLES

Table Description Page



2.1 Difference between C&A and M&E systems ………………………………. 14
2.2 Class or rank for rating failure mode ……………………………………… 26
2.3 Summary of major grading systems ……………………………………… 29
2.4 Setting weights for criteria of GBTool) …………………………………… 32
2.5 Random Consistency Index ……………. ………………………………… 38
2.6 Comparison of major MCDA methods …………………………………… 39
2.7 Summary of findings from literature review ……………………………… 40
3.1 Rating class of building defects ……………………………………… 46

3.2 Various location options used in AHP model ………………………………. 56
3.3 The 9-point pair-wise comparison scale (Saaty, 1996) …………………… 59
3.4 Structure of AHP questionnaire ……………………………………… 59
4.1 Details of case study buildings …………………………………………… 69
4.2 Significance of grading criteria and building subsystems ………………… 70
4.3 Common defects in basement and their causes …………………………… 73
4.4 Criticality analysis defects in basement …………………………………… 75
4.5 Common defects in facade and their causes ……………………………… 78
4.6 Criticality analysis defects in facade ……………………………………… 84
4.7 Common defects in wet area and their causes ……………………………… 85
4.8 Criticality analysis defects in wet area …………………………………… 89
4.9 Common defects in flat roof and their causes ………………………………. 91
4.10 Criticality analysis defects in roof ………………………………………… 95
4.11 Common defects in sanitary-plumbing system and their causes …………… 97
4.12 Criticality analysis defects in sanitary-plumbing system ………………… 101
4.13 Common defects in HVAC system and their causes ……………………… 104
4.14 Criticality analysis defects in HVAC system ……………………………… 108
4.15 Common defects in elevator and their causes ……………………………… 110
4.16 Calculation of criticality index (Cr) of defects in elevator …………………. 114
4.17 Common defects in electrical system and their causes …………………… 118
4.18 Criticality analysis of defects in electrical system ………………………… 122
4.19 Common defects in fire protection system and their causes ……………… 125
4.20 Criticality analysis defects in fire protection system ………………………. 128
4.21 Average % of defects for C&A and M&E systems ………………………… 131
5.1 Maintainability factors for basement and their RWs ……………………… 134
5.2 Maintainability factors for facade and their RWs ………………………… 136
5.3 Maintainability factors for wet area and their RWs ………………………… 138
5.4 Maintainability factors for roof and their RWs …………………………… 140
5.5 Maintainability factors for sanitary-plumbing system and their RWs ……… 142
5.6 Maintainability factors for HVAC system and their RWs ………………… 144

5.7 Maintainability factors for elevator and their RWs ………………………… 147
5.8 Maintainability factors for electrical system and their RWs ……………… 149
5.9 Maintainability factors for fire protection system and their RWs ………… 152
5.10 No. of maintainability factors ………………………………………………. 154
6.1 Six classifications of data set ………………….……………………………. 157
6.2 Illustrative example of IR chart …………………………………………… 158
6.3 Rank reversal with change in IR ………………….………………………… 160
6.4 Renormalized LW of for all zone-height combinations ……………………. 161
6.5 Derivation of GW for location = residential zone and height = low ……… 162
6.6 GWs of building subsystems for all location-height combinations ………… 162
6.7 Ranking of nine subsystems for all locations and heights ………………… 169
6.8 Application of GW in calculation of final score ……………………………. 172

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Table Description Page



7.1 Prototype scoring for basement ………………….…………………………. 174
7.2 Prototype scoring for facade ………………….………………….…………. 177
7.3 Prototype scoring for wet area ………………….………………………… 179
7.4 Prototype scoring for roof ………………………………………………… 181
7.5 Prototype scoring for sanitary-plumbing system …………………………… 183
7.6 Prototype scoring for HVAC system ………………….……………………. 185
7.7 Prototype scoring for elevators ………………….………………………… 188
7.8 Prototype scoring for electrical system ………………….………………… 190
7.9 Prototype scoring for fire protection system ………………….……….…… 193
7.10 Prototype scoring for entire building ………………….……………………. 195
C.1.1 Grading for waterproofing system selection ………………….…………… 275
C.1.2 Grading for design of structural concrete ………………….……………… 276

C.1.3 Grading for design of tanked protection (Type A) system …………………. 278
C.1.4 Grading for design of waterstops ………………….……………………… 279
C.1.5 Grading for design of cavity ……………………………………………… 280
C.1.6 Grading for design of drainage ………………….………………………… 281
C.1.7 Grading for design of flooring ………………….………………………… 282
C.1.8 Grading for selection of wall finishes ………………….…………………… 282
C.1.9 Grading for consideration for ancillary facilities ………………….……… 282
C.1.10 Grading for construction of structural concrete …………………………… 283
C.1.11 Grading for installation of water proofing membrane (Type A) …………… 284
C.1.12 Grading for installation of waterstops ………………….………………… 284
C.1.13 Grading for construction of cavity ………………….………………………. 284
C.1.14 Grading for construction of flooring ……………………………………… 285
C.1.15 Grading for application of wall finishes …………………………………… 286
C.1.16 Grading for maintenance …………………………………………………… 287
C.1.17 Guideline for maintenance of internal and cavity drainage ………………… 287
C.2.1 Grading for wall system selection ……………………………………… 288
C.2.2 Grading for weather resistance …………………………………………… 289
C.2.3 Grading for wall finishes selection ……………………………………… 290
C.2.4 Grading for wall joints ………………………………… ………………… 292
C.2.5 Design of expansion joint ………………………………………………… 294
C.2.6 Grading for sealant detail …………………………………………………… 294
C.2.7 Grading for accessibility design …………………………………………… 295
C.2.8 Grading for design of access system ……………………………………… 296
C.2.9 Grading for window design ………………………………………………… 296
C.2.10 Grading for consideration for ancillary facilities …………………………… 299
C.2.11 Grading for construction of masonry ……………………………………… 299
C.2.12 Grading for erection of PC cladding ……………………………………… 300
C.2.13 Grading for erection of cladding …………………………………………… 302
C.2.14 Grading for application of sealant ………………………………………… 303
C.2.15 Grading for regular maintenance of facade ………………………………… 304

C.2.16 Guidelines for maintenance of exposed brick wall …………………………. 304
C.2.17 Guidelines for maintenance of concrete and plastered wall …………… … 304
C.2.18 Guidelines for maintenance of painted wall: gloss/ semi-gloss enamels …… 305
C.2.19 Guidelines for maintenance of tiled wall …………………………………… 305
C.2.20 Guidelines for maintenance of natural stone wall ………………………… 305
C.2.21 Guidelines for maintenance of glass (curtain wall & window) …………… 305
C.2.22 Guidelines for maintenance of metal cladded wall. ………………………… 306
C.3.1 Grading for design of floor ……………………………………… 307
C.3.2 Grading for waterproofing selection ……………………………………… 308
C.3.3 Grading for detailing of waterproofing …………………………………… 309
C.3.4 Grading for design of piping layout ……………………………………… 311

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Table Description Page



C.3.5 Grading for design of fixture and fittings ………………………………… 312
C.3.6 Grading for design of floor and wall tiles ………………………………… 313
C.3.7 Grading for selection of paint ………………………………………………. 314
C.3.8 Grading for design consideration of ancillary facilities …………………… 315
C.3.9 Grading for construction of slope in floor ……………………………… … 315
C.3.10 Grading for installation of waterproofing ……………………………… … 315
C.3.11 Grading for installation of finishes (tiles) ………………………………… 316
C.3.12 Grading for installation of fixture and fittings ……………………………… 317
C.3.13 Grading for regular maintenance of wet area ……………………………… 317
C.3.14 Guidelines for maintenance of wall and floor finishes …………………… 318
C.3.15 Guidelines for maintenance of fixture and fittings ………………… …… 318
C.4.1 Grading for selection of roofing systems …………………………………… 319
C.4.2 Grading for design of concrete deck ……………………………………… 320

C.4.3 Grading for selection of waterproofing membrane ………………… …… 321
C.4.4 Grading for detailing of waterproofing membrane ………………… …… 322
C.4.5 Grading for design of insulation ……………………………………………. 323
C.4.6 Grading for sealant detail …………………………………………………… 324
C.4.7 Grading for design of drainage …………………………………………… 324
C.4.8 Grading for design of drainage outlets and RWDP ………………… …… 325
C.4.9 Grading for design consideration of ancillary facilities …………………… 326
C.4.10 Grading for construction of deck …………………………………………… 326
C.4.11 Grading for installation of waterproofing ………………………………… 327
C.4.12 Grading for laying the thermal insulation & protective surface ……………. 328
C.4.13 Grading for installation of drainage system ………………………………… 329
C.4.14 Grading for maintenance …………………………………………………… 329
C.4.15 Guideline for maintenance of roof ………………………………………… 330
C.5.1 Grading for water supply piping system ……………………………………. 331
C.5.2 Grading for hot water supply ……………………………………………… 333
C.5.3 Grading for design of storage tank …………………………………………. 335
C.5.4 Grading for design of general and sewage pumps ………………………… 336
C.5.5 Grading for design of sanitary appliances ………………………………… 336
C.5.6 Grading for design of sanitary piping ………………… ………………… 337
C.5.7 Grading for design of sewage ejector & solid diverter tank ……………… 339
C.5.8 Grading for design of sewer drains ………………………………………… 339
C.5.9 Grading for installation of water supply piping …………………… ……… 341
C.5.10 Grading for construction of water storage ………………………………… 341
C.5.11 Grading for installation of pumps …………………………………… …… 342
C.5.12 Grading for installation of sanitary appliances ………………………… … 342
C.5.13 Grading for installation of sanitary piping ………………………………… 343
C.5.14 Grading for installation of sewage ejector & solid diverter tank …………… 343
C.5.15 Grading for installation of sanitary piping ………………………………… 343
C.5.16 Grading for maintenance of sanitary-plumbing system …………………… 344
C.5.17 Guidelines for maintenance of sanitary-plumbing system …………………. 344

C.6.1 Grading for design of AHU and FCU ………………… ………………… 347
C.6.2 Grading for design of FCU ………………… ……………………… …… 349
C.6.3 Grading for design of chiller ………………… …………………………… 350
C.6.4 Grading for design of cooling tower ……………………………………… 351
C.6.5 Grading for design of air distribution system ……………………………… 352
C.6.6 Grading for installation of HVAC system components …………………… 354
C.6.7 Grading for maintenance …………………………………………………… 355
C.6.8 Guidelines for maintenance of AHU & FCU ……………………………… 355
C.6.9 Guidelines for maintenance of chiller plant ………………………………… 356
C.6.10 Guidelines for maintenance of cooling tower ……………………………… 356

xi
Table Description Page



C.6.11 Grading for maintenance of air distribution system ……………………… 356
C.7.1 Grading for planning of elevator …………………………………………… 358
C.7.2 Grading for design of machine room ……………………………………… 359
C.7.3 Grading for general design considerations for machines …………………… 359
C.7.4 Grading for design of roping system ………………… …………………… 360
C.7.5 Grading for design of hoistway and its components ………………… …… 362
C.7.6 Grading for design of elevator car or cab ………………………………… 363
C.7.7 Grading for design of landing ……………………………………………… 364
C.7.8 Grading for design of car door and lobby door …………………………… 364
C.7.9 Grading for design of lift pit ……………………………………………… 364
C.7.10 Grading for consideration for ancillary facilities …………………………… 365
C.7.11 Grading for construction of structural elements …………………………… 365
C.7.12 Grading for installation of equipment ………………… ………………… 366
C.7.13 Grading for lubrication …………………………………………………… 367

C.7.14 Grading for maintenance …………………………………………………… 367
C.7.15 Guideline for maintenance of machine room and its equipment …………… 368
C.7.16 Guideline for maintenance of elevator car ………………………………… 369
C.7.17 Guideline for maintenance of hoistway, landing and pit …………………… 370
C.7.18 Guideline for maintenance of lobby and car door ………………… ……… 370
C.8.1 Grading for design of system in general ……………………………………. 371
C.8.2 Grading for design of transformer ………………………………………… 372
C.8.3 Grading for design of cable conductor …………………………………… 373
C.8.4 Grading for design of cable layout ………………………………………… 374
C.8.5 Grading for design of busway ……………………………………………… 375
C.8.6 Grading for design of connectors ………………………………………… 376
C.8.7 Grading for design of distribution equipment ……………………………… 376
C.8.8 Grading for design of protection device ………………… ……………… 378
C.8.9 Grading for design of lighting system ……………………………………… 379
C.8.10 Grading for design of standby and emergency power supply ……………… 380
C.8.11 Grading for design of grounding system………………………………… 381
C.8.12 Grading for design of LPS ………………………………………………… 382
C.8.13 Grading for design consideration of ancillary facilities …………………… 382
C.8.14 Grading for installation of transformer ………………… …………………. 382
C.8.15 Grading for installation of wiring system ………………………………… 383
C.8.16 Grading for installation of distribution and protective device……… …… 384
C.8.17 Grading for installation of lighting ………………… …………………… 384
C.8.18 Grading for installation of emergency / standby power supply …………… 384
C.8.19 Grading for installation of grounding and LPS ……………………… …… 385
C.8.20 Grading for maintenance …………………………………………………… 386
C.8.21 Guideline for maintenance of wiring system ………………………… …… 387
C.8.22 Guideline for maintenance of distribution equipment ………………… … 387
C.8.23 Guideline for maintenance of control & protective device ………………… 388
C.8.24 Guideline for maintenance of lighting ……………………………………… 388
C.8.25 Guideline for maintenance of emergency / standby power supply …………. 388

C.8.26 Guideline for maintenance of grounding system & LPS …………………… 389
C.9.1 Grading for detector selection …………………………… ……………… 390
C.9.2 Grading for design of alarm system ………………………………………… 391
C.9.3 Grading for design of fire hydrant and accessories ………………………… 392
C.9.4 Grading for design of fire hose …………………………… ………………. 392
C.9.5 Grading for design of sprinkler system …………………………………… 393
C.9.6 Grading for selection of portable fire extinguisher ………………………… 394
C.9.7 Grading for design of fire door …………………………………………… 394
C.9.8 Grading for design of services for fire escape ……………………………… 395

xii
Table Description Page



C.9.9 Grading for installation of detector and alarm ……………………………… 396
C.9.10 Grading for installation of fire hydrant and hose …………………………… 397
C.9.11 Grading for installation of sprinkler system ……………………………… 397
C.9.12 Grading for installation of portable extinguisher …………………………… 398
C.9.13 Grading for installation of fire door ………………………………………… 398
C.9.14 Grading for maintenance …………………………… …………………… 399
C.9.15 Guideline for maintenance of detector and alarm ………………… ……… 399
C.9.16 Guideline for maintenance of fire hydrant and hose ……………… ……… 400
C.9.17 Guideline for maintenance of sprinkler system …………………………… 400
C.9.18 Guideline for maintenance of portable fire extinguishers ………………… 402
C.9.19 Guideline for maintenance of fire door …………………………………… 402
C.9.20 Guideline for maintenance of services for safe escape …………………… 403

xiii
LIST OF FIGURES

Fig. Description Page


2.1 Elements of a building………………………………………………………. 15
2.2 ANN model for risk analysis of facade…………………………………… 23
2.3 Example of a sample Fault Tree Analysis………………………………… 24
2.4 Example of a sample Fishbone Diagram……………………………………. 24
2.5 Typical example of FMECA hierarchy…………………………………… 25
2.6 Basic steps of FMECA…………………………………… 25
2.7 Criticality grid…………………………………… 26
2.8 Basic Structure of CASBEE…………………………………… 33
2.9 Graphical computation of BEE…………………………………… 34
2.10 A typical AHP hierarchy…………………………………… 38
3.1 Flowchart of research methodology ……………………………………… 43
3.2 ‘Visual cookies’ used to highlight building subsystems …………………… 49
3.3 The hierarchy model for building maintainability ………………………… 55
3.4 Building height vs. complexity of building systems ……………………… 58
3.5 Graphical symbols to denote various locations and height of the building … 59
4.1 Demography of the respondents ……………………………………………. 69
4.2 Common defects in basement ………………………………………………. 72
4.3 Common defects in facade ………………………………………………… 76
4.4 Common defects in wet area ……………………………………………… 88
4.5 Common defects in flat roof ……………………………………………… 90
4.6 Common defects in sanitary-plumbing system …………………………… 96
4.7 Common defects in HVAC system …………………………………………. 103
4.8 Common defects in elevator ……………………………………………… 109
4.9 Relationship of accidents of increasing severity of consequences …………. 116

4.10 Common defects in electrical system ………………………………………. 117
4.11 Common defects in fire protection system …………………………………. 124
4.12 Comparison of defect causes and criticality of nine subsystems …………… 130
5.1 Schematic diagram of electrical system of commercial building ………… 149
6.1 Demography of the respondents …………………………………………… 155
6.2 Data procession in ExpertChoice (EC) ………………….…………………. 156
6.3 Comparison of years of experience and consistency of results ……………. 158
6.4 GW for nine –subsystems ………………….………………….…………… 159
6.5 Variation of GWs with location, keeping the height constant ……………… 164
6.6 Variation of GWs with height, keeping the Location constant …………… 164
6.7 RWs of various (a) locations and (b) heights ………………….…………… 165
6.8 RWs of C&A and M&E systems for various locations and heights ……… 166
6.9 RW of C&A and M&E systems with variance in (a) location and (b) height 167
6.10 Relative weights of C&A systems for various locations and heights ………. 168
6.11 Relative weights of M&E systems for various locations and heights ……… 168
7.1 Variance of MS and RW for subsystems ………………….……………… 196
7.3 Interface of ‘Maintainability of Buildings’ website ……………………… 198
7.4 Three level hierarchy of Defect Library interface …………………………. 198
7.5 Compilation of defects, photos and analysis of causes …………………… 198
7.6 Interface of maintainability scoring system ………………….…………… 199
C.1.1 Various types of waterproofing systems…………………………………… 275
C.1.2 Penetration thru’ water/ vapour proofing membrane……………………… 279
C.1.3 Various types of water stops………………………………………………… 279
C.1.4 Details of surface water drainage……………………………………………. 281
C.1.5 Various pointing (L to R): flashed struck, keyed & recessed……………… 285
C.2.1 Various types of wall system ……………………………………….……… 289

xiv
Fig. Description Page

C.2.2 Drainage detail in curtain wall and cladding ………………….……………. 290
C.2.3 Various types of wall joint ………………….………………………………. 291
C.2.4 Various options of joint exposure ………………….……………………… 292
C.2.5 Drainage detail in curtain wall ………………….………………………… 293
C.2.6 Expansion joint details ………………….………………….……………… 294
C.2.7 Sealant joint details ………………….………………….…………………. 294
C.2.8 Various window details ………………….………………….……………… 298
C.2.9 Accessibility parameters of a window ………………….………………… 299
C.2.10 Various pointing (L to R): flashed struck, keyed & recessed……………… 300
C.2.11 Sealant application: scraping, masking tape removal, tooling ……………… 303
C.3.1 Zoning by using kerb and level difference……………………… 307
C.3.2 Typical detail for drainage……………………… ……………………… 307
C.3.3 Typical details of waterproofing in wet area……………………… 310
C.3.4 Example of multiple fixture connected to a single trap…………………… 311
C.3.5 Water closet: floor mounted and wall hung……………………… ……… 312
C.3.6 Leakage at the junction of discharge & gully pipe……………………… 317
C.4.1 Various types of roofing system ………………….………………….…… 319
C.4.2 Typical Joint and penetration details for waterproofing ………….………… 322
C.4.3 Typical detail of vent in BUR ………………….………………….……… 323
C.4.4 Formation of staggered side laps ………………….………………….…… 328
C.5.1 Connection to the top of the hot water cylinder ……………………………. 333
C.5.2 Details of water supply pipe design ………………….………………….… 334
C.5.3 Location of storage tank ………………….………………….…………… 335
C.5.4 Air gap ………….……………………….……………………….………… 336
C.5.5 Various types of trap seal details ………………….………………….…… 337
C.5.6 Details of branch ventilation pipe and cross venting ………….…………… 337
C.5.7 Various types of sanitary pipe work systems ………………….…………… 338
C.5.8 Components of a Sewage ejector in a diverter tank………….… ………… 339
C.5.9 Backdrop and tumbling bay in IC/ MH connection………….……………… 340

C.5.10 Laying of sewers ………………….………………….…………………… 344
C.6.1 Various types of air filters ………………….………………….…………… 349
C.6.2 Various types of compressors ………………….………………….……… 350
C.6.3 Adequate size of access opening ………………….………………….……. 352
C.6.4 Various types of diffusers ………………….………………….……………. 353
C.6.5 Damper blade arrangement: opposed and direct ………….………………… 353
C.6.6 Checking alignment with K-bar and V-belt tension ………….…………… 356
C.7.1 Various types of sheave groove ………………….………………….……… 360
C.7.2 Balance mechanism for suspension rope ………….……………………… 361
C.7.3 Rope configuration: 6-strands and 8-strands ………….…………….……… 361
C.7.4 Various types of rope lays ……………….………………….……………. 361
C.7.5 Straightness of guiderail………………….………………….……………… 362
C.7.6 Example of general purpose passenger lift – small and big ………….…… 364
C.8.1 Schematic diagram of electrical system of commercial building ………… 371
C.8.2 Details of a standard busway………………….………………….………… 373
C.8.3 Cable through wall and joist ………………….………………….………… 375
C.8.4 Main loadcentre & main panel with sub-panel ………………….………… 378
C.8.5 Earth reisitivity measurement - Four probe method ……………………… 385
C.9.1 Details of fire hose reel and cabinet ………………….…………………… 393
C.9.2 Details of a fire door ………………….………………….…………………. 395


xv
LIST OF ACRONYMS

Acronym Full Name

AHP Analytic Hierarchy Process
AHU Air Handling Unit
AIP Aggregating Individual Priorities

ANOVA Analysis of Variance
ANSI American National Standards Institute
ARI Air-Conditioning and Refrigeration Institute
ARMA Asphalt Roofing Manufacturers Association
ASHRAE American Society of Heating, Refrigerating and Air-Conditioning
ASME American Society of Mechanical Engineers
ASTM American Society for Testing and Materials
BAS Building Automation System
BCA Building and Construction Authority
BMU Building Maintenance Unit
BRE Building Research Establishment (UK)
BSI British Standards Institute
BUR Built-Up Roofing
CBD Central Business District
CIB Building Maintenance Unit
CIDB Construction Industry Development Board
CIRIA Construction Industry Research and Information Association
COMASS Comprehensive Maintainability Scoring System
CONQUAS Construction Quality Assessment System
COP Car Operating Panel
CP Code of Practice
Cr Criticality Index
CR Consistency Ratio
CTC Constriction21 (C21) Committee
DB Distribution Board
DFT Dry Film Thickness
DL Defect Library
DM Decision Maker
DPC Damp Proof Course
EC ExpertChoice

FCU Fan Coil Unit
FM Facility Manager
FMECA Failure Mode Effects and Criticality Analysis
GDM Group Decision Making
GFCI Ground Fault Circuit Interrupter
GMM Geometric Mean Method
GW Global Weight
IC Inspection Chamber
IEE Institution of Electrical Engineers
IEEE Institution of Electrical & Electronics Engineers
IR Inconsistency Ratio
KPI Key Performance Indicator
LAM Liquid Applied Membrane
LCC Life Cost
LED Light Emitting Diode
LPS Lightning Protection System
LW Local Weight

xvi
Acronym Full Name

MCDA Multiple Criteria Decision Analysis
MH Manhole
MS Maintainability Score
NEC National Electrical Code
NEMA National Electrical Manufacturers Association
NFPA National Fire Protection Association
NRC National Research Council (Canada)
NUS National University of Singapore
OSHA Occupational Safety & Health Administration (Us)

PC Precast Concrete
PUB Public Utilities Board
PWD Public Works Dept.
RCC Reinforced Cement Concrete
RW Relative Weight
RWDP Rain Water Down Pipe
SBS Sick Building Syndrome
SCDF Singapore Civil Defence Force
SFPE Society of Fire Protection Engineers
SMCNA Sheet Metal & Air Conditioning Contractors' National Association
SPSS Statistical Package for The Social Sciences
SS Singapore Standards
Sv Severity Index
UG Under Ground
URA Urban Redevelopment Authority
VAV Variable Air Volume
WC Water Closet
WVT Water Vapor Transmitivity



xvii
Chapter 1 Introduction
1.1 Background
1.1.1 The concept of maintainability and maintenance
The maintainability of buildings is a key initiative of Construction 21 or C21 – the blue print
for reforming Singapore’s construction industry in 21st century (CTC, 1999). Much earlier in
1901 the concept of maintainability came into existence through US Army Signal Corps’
contract for Wright brothers’ airplane that stated that ‘ should be simple to operate and
maintain’ (Dept of Defence, 1976) and the first book on maintainability was published in

1960 titled Electronic Maintainability (Ed. F.L. Akenbrandt).

Maintainability is a design characteristics and maintenance is the result of design (Blanchard,
Verma & Peterson, 1995). British Standards Institute (BSI) defines maintainability as ‘the
ability of an item, under conditions of use, to be retained in or restored to a state in which it
can perform its required functions, when maintenance is performed under stated conditions
and using prescribed procedures and resources’ (BS 3811). While building maintenance is
defined by Chartered Institute of Building or CIB (1990) as ‘work undertaken in order to
keep, restore, or improve every part of the building, its services and surrounds, to currently
accepted standards, and to sustain the utility and value of the building’. Hence it can be
inferred that conceptually maintainability and maintenance are inversely related i.e. a building
with high maintainability requires lesser maintenance and vice versa.

Historically, maintenance has been considered as a ‘necessary evil’ - an obligatory cost
burden for projects (Moua & Russell, 2001). But over time, this negative perception has
changed to the main support for the core income generation activities of an organization
(Quah, 1998). Hence defining maintenance by life cycle cost (LCC) has been replaced by
performance (Hassanain, Froese & Vanier, 2003; Vanier, Lacasse & Parsons, 1996). In

1
today’s context of higher user expectation, the performance based concept introduced by CIB
(1990) has received a better acceptance than the theory proposed by BSI 3811. Finch (1998)
argued that the BS 3811 definition fails to ‘address the obsolescence gap developed from
increased functional and technological demands. If this issue is not continually addressed,
ultimately it leads to the building’s untimely demise’.
1.1.2 Significance of maintainability
The notion of maintainability has been manifesting during the past decade because building
owners demand more durable buildings. As buildings start to deteriorate from the moment
they are completed and incur maintenance cost (Arditi, & Nawakorawit, 1999b), proper
maintenance should be planned to control and defer this inevitable process of deterioration

(Chew, Tan & Kang, 2004). However maintenance of modern buildings with growing
complexity, higher proportion of more sophisticated systems and higher level of service
requirement (Shohet & Perelstein, 2004) together have resulted in ever increasing
maintenance cost to be fitted in decreasing maintenance budget. As a response to this
scenario, maintainability has been prioritized over maintenance ever than before (Bourke &
Davies, 1997; Cane, Morrison & Ireland, 1998; Cash, 1997a, b; Horner, El-Haram & Munns,
1997; Shohet, Puterman, & Gilboa, 2002, Underwood & Alshawi, 1999; Van Winden &
Dekker, 1998).
1.1.3 Research problem – A paradoxical situation in Singapore
Maintainability has even higher significance in Singapore due to its tropical climate and
economic profile. Building components need additional maintenance in tropics as alternate
dry and wet seasons shorten lifespan of materials to a great extent (Chew, Tan & Soemara,
2004). But standard of maintenance or more precisely the standard of building performance
can not be compromised in Singapore as the country survives as the business hub of South
East Asia. It needs to compete and outwit other centres of growth such as, Shanghai, Hong
Kong or Kuala Lumpur. A global standard of facility is must in order to attract and retain

2
global clients (Moore & Finch, 2004; Tay, 2006). Direct maintenance expenditure for office
buildings in the Central Business District has tripled in just 10 years (BCA, 2000; CIDB,
1999). Hence the paramount importance of maintainability in Singapore context is palpable.

This fact was given official recognition through the formation of C21 committee which
established maintainability as one of the key strategic thrusts and proposed strongly the
establishment of a maintainability assessment system to grade the performance of buildings as
a major step to upgrade the service level of Singapore construction industry (CTC, 1999).
Apart from this, codes, standards and performance based initiatives customised for Singapore
climate and construction industry have been planned profoundly. During a short period of
1999 - 2005, total ten schemes have been implemented for benchmarking, grading,
government incentive / penalty and recommendations for buildable design, improved

workmanship and energy efficiency (Das, 2007). But the output is not as commendable as it
was expected. In a research project titled ‘Maintainability of Buildings in the Tropics’ by
Building & Construction Authority (BCA) and National University of Singapore (NUS) in
2002-2004, condition survey of 450 buildings aged between 1-30 years and with height range
of 4–60 storeys was conducted. It revealed that defects are prevalent in almost all major
building elements - keeping them under constant maintenance. Facade and wet area itself
demonstrated 51 and 14 defects respectively (Chew, De Silva & Tan, 2004; Chew, 2005). A
bigger surprise came through Chong & Low’s (2006) work. They found more than 18,704
defects in 74 buildings 2 - 6 years old i.e. in an average more than 250 defects per building
that are almost new.

This is an alarmingly high number especially in a country like Singapore where (1) user
expectation and possible drawbacks are well defined; (2) building guidelines are advanced
and (3) their implementation is strictly enforced by law (Donohoe, 1999). Hence it was
apparent that there was a missing component causing an imbalance between the input and

3
output. This is a paradoxical situation requiring urgently a probing investigation and thus led
to the following research questions:
1. What are the key factors that affect maintainability and how do they influence?
2. How to measure maintainability to select best building alternative?
1.1.4 Rationale of the study
While searching answers for the research questions, it was realized that a few major hurdles
to be overcome before reaching a conclusion. These roadblocks as mentioned by previous
researchers (Arditi, et al, 1999b; De Silva, Dulaimi, Ling, & Ofori, 2004; Korka, Oloufa &
Thomas, 1997) are:
● Dearth of knowledge database of defect.
● Dearth of system selection framework.
● Lack of communication.
1.1.4.1

Dearth of knowledge database of defect
Defects are responsible for poor maintainability which is a composite of many factors,
namely, (1) systems and designs; (2) materials; (3) performance; (4) the risk of failures
associated with systems and components (Chew & De Silva, 2004). These root causes can be
further elaborated as design, detailing, material, construction quality, micro-environment, and
maintenance practices (Gambardella & Moroni, 1990; Honstede, 1990; Olubodun, 1996).
Design, construction and maintenance were accountable for 40%, 30% and rest 30% of
building defects in Hong Kong (Lam, 2000). In Singapore this ratio was 84% (design 60% +
material 24%), 33% and 4% as well as few defects with multiple causes (Chong & Low,
2006). Though maintenance is the longest phase of building lifecycle when the defects
become apparent, holding facility managers responsible for defects (Tay & Ooi, 2001) is
highly debatable.

There is no centralised defect database where facility managers can provide feedback to the
designers and both can seek solutions for their problems. Such knowledge-base using existing

4
information and awareness of designers can prevent defective designs. This lack of
knowledge or information, unawareness, wrong assumptions and moreover poor motivation
contribute to the decision errors (Andi & Minato, 2003). Consequently many defects recur in
every building (Chong, & Low, 2006). Wardhana & Hadipriono (2003) provides a plausible
solution by making an updated defect database accessible for public. They suggest a web
based version is the most effective as it can save time, cost and hassle.
1.1.4.2
Dearth of system selection framework
Unlike maintenance, maintainability carries a far fetching effect of decisions made during
design stage (Briffet, 1990). That is why the influence of design on the buildings is greater
than ever before. By preventing or rather ‘design-out’ defects almost half of the maintenance-
related problems could be eliminated (Arditi, & Nawakorawit, 1999a & b). Defects especially
those due to fundamental design errors can exhibit a chain effect, hinder building

performance and impose spiralling cost burdens (Josephson & Hammarlund, 1999; Ilozor,
Okoroh & Egbu 2004). Moreover plethora of modern construction materials and techniques
pose a challenge to the designers. Any erroneous selection of systems can seriously affect the
durability, service life, sustainability, cost of repair and refurbishment of the building, and in
turn, additional liabilities would be incurred to the building owners. Realizing that ‘trial and
error approaches are inefficient and impossible’, Aygun (2000) expressed an urgent need for
an analytical model for systematic selection process.

Purely design related issues, namely, selection of systems, components and material should be
dealt in details. Unfortunately the selection is guided by over-emphasized initial cost (Wong
& Li, 2006), which is hardly 25% of the total LCC (Griffin, 1993) and hence judging
economic viability of projects by this initial cost may not be the most economical solution.
Cheaper materials often require more frequent maintenance (Wong, 1993). Even proposal of
using LCC (Architectural Institute of Japan, 1995; Bromilow & Pawsey, 1987; Flanagan &
Norman, 1987; Griffin, 1993; ISO 15686-5; McDermott, Torrance & Cheesman, 1987) was

5
highly challenged (Arditi & Messiha, 1996; Fuller & Petersen, 1995; Haasl & Sharp, 1999) as
cost greatly depends on operation & maintenance strategy and results can be particularly
erroneous due to the attitude of cost-cutting (Shen, Lo & Wong, 1998). Moreover LCC
technique requires large amount of data and is not always practical (Louis & Vanier, 2000).
1.1.4.3
Lack of communication
‘Maintenance and design are frequently treated as if the two activities were
unconnected…Maintenance sections often appear to be self-contained… [resulting in] risk of
undesirable divorce from other related functions’ (LAMSAC, 1981). Maintenance priority has
been well researched by Alibaba & Özdeniz (2004); Caccavelli & Genre (2000); Fwa & Chan
(1993); Hayashi (2000); Pullen, Attkinson, & Tucker (2000); Reddy, Coskunoglu & Sucur
(1994); Shen, & Lo (1999); Spedding, Holmes, & Shen (1995); Shohet (2003). On the other
hand tools such as HQAL, BDAS (CIDB, 1999) and CONQUAS 21 (BCA, 2005) can

evaluate durability, buildable design and construction quality respectively. Unfortunately
these two groups are not integrated. Consequently, design decisions are based on incomplete
knowledge as long-term performance of such decisions are not available (Chong & Low,
2006). The reluctance of various stakeholders to embrace further responsibility and liability to
bridge this communication gap is an obstacle in improved maintainability of buildings in
Singapore. De Silva et al. (2004) argue that till date there is no initiative to articulate the need
of informed decision making to set priority keeping aside ‘the lowest cost’ mentality.
1.2 Research guideline
In order to obtain a complete understanding of the multifaceted issue of maintainability, the
subject was studied from various angles. An extensive literature review was conducted on
related topics, namely, building elements, associated defects, maintenance, maintainability,
holistic building grading systems and their mathematical principles. From the identified
knowledge gap, the research guideline was formulated in terms of aim, objectives, hypothesis
and scope.

6