A practical guide to diagnosing structural movement in buildings

Many surveyors are nervous about diagnosing cracks. This is understandable, as the interpretation of cracks can be difficult to teach, with university courses providing little or no time for field experience. Yet by understanding one straightforward principle the majority of cracks can be diagnosed in just a few minutes. Linking this with a good knowledge of construction techniques, the factors that distort cracking patterns and the key features of common causes of cracking, almost all cracks can be diagnosed quickly and with confidence.

Practical Guide to Diagnosing Structural Movement in Buildings provides a methodology by which cracks and movement in buildings can be diagnosed. Written in four parts, part one describes the key principles of movement and cracking. Parts two and three describe the main features of common forms of movement and the associated crack patterns. Part two covers causes other than ground or foundation movement and part three covers movement caused by ground or foundation problems. Part four briefly describes the techniques used to arrest further movement or repair damage cause by movement.

Primarily intended for the relatively inexperienced surveyor or engineer and undergraduate students of surveying as a practical guide for use on site, it focuses on identification and diagnosis. It will not only help in correctly diagnosing the problem but it will also demonstrate a methodical approach to show and record how the diagnosis was reached - critical when giving advice to third parties.

"What's the crack?" - In the vast majority of cases it's not foundation related and in most cases it's not indicating a serious defect.

Author Notes

Malcolm Holland, BSc(Hons) MRICS, started his career as a land surveyor in the Royal Engineers before leaving the Army to return to higher education. He gained a degree in Building Surveying and then qualified as a Chartered Surveyor in 1988. Since then he has worked predominantly in private practice and mostly in the field of residential surveying. During the mid 1990s he spent 4 years as a senior lecturer at DeMontfart University teaching building construction and pathology to general practice surveying students. He returned to private in 1997 and continues to practice as a residential building surveyor.

Introduction	p. viii
List of Figures	p. xi
Acknowledgements	p. xvi
Part 1 First Principles	p. 1
1.1 First Principles	p. 3
1.2 Crack Patterns and Cracks	p. 8
1.3 Rotational Movement	p. 9
1.4 Contra Rotational Movement	p. 11
1.5 Weak Routes	p. 14
1.6 Load Distribution	p. 22
1.7 Movement and Orientation	p. 26
1.8 Summary of First Principles and Process	p. 28
Part 2 Cracks in Buildings not Related to Foundations	p. 31
2.1 Expansion Cracking	p. 33
2.2 Cavity Wall Tie Corrosion	p. 44
2.3 Corrosion of Metal Built into Walls	p. 53
2.4 Vibration of Built in Fixings	p. 57
2.5 Roof Spread	p. 60
2.6 Springing from Deflected Beams	p. 67
2.7 Lack of Lateral Stability	p. 70
2.8 Lack of Lateral Stability in Modern Gable Walls	p. 76
2.9 Overloaded Beams	p. 79
2.10 Absence of Lintels (Beams) Over Openings in Cavity Walls	p. 84
2.11 Overloaded Floors	p. 91
2.12 Overloaded Walls	p. 95
2.13 Differential Movement	p. 99
2.14 Arch Thrust and Arch Flattening	p. 101
2.15 Load Path Cracking	p. 109
2.16 Bulging of Walls due to Decay of Bonding Timbers	p. 112
2.17 Bulging and Separation in Solid Brick Walls	p. 115
2.18 Separation of Rubble Filled Stone Walls	p. 118
2.19 Floor Slab Settlement (Compaction)	p. 120
2.20 Load Concentrations	p. 127
2.21 Sulphate Attack	p. 129
2.22 Concrete Block Shrinkage	p. 134
2.23 Shrinkage of Calcium Silicate Bricks	p. 138
Part 3 Cracks in Buildings Related to the Foundations and Ground Movement	p. 141
3.1 Introduction	p. 143
3.1.1 Design for Load	p. 145
3.1.2 Design for Stability	p. 147
3.1.3 Identifying Below Ground Defects	p. 143
3.2 Foundation Movement Caused by Clay Shrinkage	p. 151
3.3 Clay Heave	p. 159
3.4 Seasonal Expansion of Clay Subsoil	p. 162
3.5 Eccentric Loading on Foundations	p. 164
3.6 Uneven Loading	p. 167
3.7 Load Concentrations on Foundations	p. 169
3.8 Differential Foundation Movement	p. 171
3.9 Initial Settlement after Construction or Alterations	p. 176
3.10 Leaking Drains and Water Discharge Near to Buildings	p. 179
3.11 Drams and Drain Trenches	p. 182
Part 4 Repair Methods	p. 185
4.1 Introduction	p. 187
4.2 Re-pointing	p. 189
4.3 Re-pointing with Epoxy Mortar	p. 191
4.4 Stitching in Brickwork	p. 192
4.5 Reinforcing Brick Mortar Joints	p. 193
4.6 Tie Bars	p. 195
4.7 Restraint Straps	p. 198
4.8 Buttresses/Piers	p. 200
4.9 Preventing Roof Spread	p. 211
4.10 Underpinning	p. 203
4.11 Expanding Foam Underpinning	p. 207
4.12 Grouting	p. 209
4.13 Root Barriers	p. 211
Index	p. 213

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Table of Contents