The severe droughts of 1975//90 brought to the public’s attention the fact that low-rise buildings are susceptible to cracking of the materials from which the buildings are constructed. However, the 1975/76 drought, whilst admittedly being more extensive than previous dry spells,įig 1 Annual value of insurance claims for subsidence and heave damage to housing Note the substantial increase following 19 – dry years 700 This is not a new phenomenon and has been experienced many times in the past. One of the many causes of damage is foundation movement resulting especially from the drying shrinkage of clay subsoil. This Digest will assist building professionals, property valuers and insurance advisors both in putting building damage into its true perspective and in determining necessary action, either in the form of seeking expert advice or in recommending simple repairs. The various causes of ground movement giving rise to damage are described briefly and emphasis is placed on the identification of conditions where the movement might lead to progressive deterioration. It is rare for damage to progress beyond Category 2 when it does ground movement is usually the cause. It is concluded that for damage of Category 2 or less, cracking may result from a combination of causes which are difficult to identify and the cost and effort involved in carrying out an identification would be disproportionate to the scale of the damage, except for circumstances where the movement is likely to be progressive. The most common causes of damage are discussed. The assessment is based on a description of work considered necessary to repair the building fabric classification into six categories is recommended, taking into account the nature, location and type of damage. Assessment of damage in low-rise buildings with particular reference to progressive foundation movement This Digest discusses the assessment and classification of visible damage resulting from structural distortion.

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