Why do buildings crack? (DG 361)

BRE (Building Research Establishment) is an independent, research-based consultancy, testing and training organisation, operating in the built environment and associated industries.

Why do buildings crack? (DG 361) was first published by BRE in May 1991, and the original content largely remains valid. The current edition was published on 21 August 2014 and includes updated references. It was written by Roger Sadgrove.

Most buildings develop cracks in their fabric, often soon after construction when materials are drying out, but sometimes later. Most early cracking is not structurally significant and is easily repaired. Only rarely does cracking indicate a reduction in structural capacity.

However, diagnosis can be difficult, as every building is unique and several factors may combine to produce a defect. DG 361 examines the causes of cracking in buildings, describes a wide range of potential problems and offers complete solutions to every cracking problem. It is intended to broaden the reader’s understanding of the factors that contribute to cracking and so increase the likelihood of correct diagnosis and remediation.

It provides guidance about how to avoid pitfalls and how to reduce the likelihood of future problems in new buildings.

The contents of the 12 page digest are:

• Introduction.
• Extent of movement.
• The effect of movements: how do cracks occur?
• Diagnosis.
• Temperature changes.
• Initial drying out of moisture and wetting and drying.
• Loss of volatiles.
• Freezing and thawing of absorbed water.
• Subsurface crystallisation of soluble salts.
• Sulfate attack.
• Corrosion or oxidation of steel.
• Moisture expansion of fired clay products.
• Carbonation.
• Alkali silica reaction.
• Hydration of oxides and unstable clinker aggregates.
• Imposed load effects.
• Foundation movement.
• Vibration.
• References.

--BRE Group

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