Introduction to cracking in buildings by Woodward Chartered Surveyors

one of the most difficult challenges facing any surveyor reporting on the building is diagnosing the causes of cracking and also recommending the most appropriate repair now here at Woodward chance surveyors with the extensive knowledge on this subject and we've basically broken the cause of cracking down into five categories the first relates to the original design and workmanship defects the second is caused by the expansion contraction to materials in the wall through temperature and moisture variations a third form of category cracking is that related to the deterioration of materials in the wall such as the decay of timber lintels and the corrosion of steel beams the fourth category relates to those unofficial structural creations undertaken by the owners but fifth and probably the most significant form of cracking is related to the failure of the ground and the Foundation's to support the building above now these cracks don't always occur in isolation but the focus of this video is to concentrate on those cracks caused by the failure of the ground and the foundations to support the building above and my colleague and fellow Chancellor Douglas Nell will actually be taking you through specific examples properties built on clay subsoil are particularly susceptible to ground movement the actions of tree roots which can cause leaching of the moisture out of the soil can cause the clay to shrink and in turn reduce the amount of support provided by the soil beneath the foundations the removal of a substantial tree in one operation can cause a situation where the subsoil will swell as a result of the moisture not being extracted by that tree this can lead to a situation known as heave and buildings built close by can develop cracking associated with the ground expanding beneath the Foundation's the cracking here extends to approximately 10 millimeters in width it also follows a stepped pattern as a rule of thumb we take the highest point of the crack measure down with a plumb line and assess the reduction in support is beneath that point the Building Research Establishment uses seven different categories to assess cracking these range from negligible to critical the cracking we see here falls into the mid middle category and as such requires repair again to the rear of the building we have stepped cracking this follows a pattern in an upwards direction and what one would normally assume that the support has been reduced beneath the highest point of the crack although this cracking isn't as wide as that noted to the front of the building it still requires a degree of repair another point to note here is that the cracking extends beneath the level of the damp proof course this is often an indication of ground instability on account of the fact that the Foundation's no longer provide adequate support leading to cracking in the brickwork beneath this can often be an indication of foundation damage in this instance the cracking does indeed extend beneath the level of the damp proof course almost down to ground level when assessing cracking it's important to differentiate between thermal movement or foundation damage caused by ground instability this small section of cracking is considered to result from thermal expansion and contraction in the brickwork this is a south-facing elevation and you'll note by way of the air brick being located in the wall and the window above this is a potentially weak point in the wall exposure to sunlight can cause expansion and contraction in the brickwork this in turn leads to the potential for it to become cracked that cracking is exacerbated in the colder months of the year where water can seep in and expand through the actions of frost in this case we can see that the movement isn't entirely horizontal as opposed to one side dropping down from the other which is often as with Ground instability the edges of the crack of weathered indicating that it could be fairly long-standing it may be the case that only cosmetic repairs are necessary however this would be subject to further investigation the long hot summer of 2018 has led to an increased incidence in the cracking of buildings where clay soils are prevalent we can assist you by undertaking a structural investigation to assess the extent of damage and suggest appropriate remedial repairs

Channel: Woodward Surveyors

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Id: ZVGJqwI2j38

Length: 5min 11sec (311 seconds)

Published: Mon Mar 11 2019