Soils and Building Movement
From February to June 2011 there had been very little rainfall in the south east. Autumn/Winter 2012/2013 was very wet followed by a dry summer in 2012. The Autumn/Winter/Spring period of 2013/2014 was even wetter than the year before followed by a very dry summer in 2014.
Large parts of the high and low Weald are founded on clay based, shrinkable sub soils. The very wet winter weather would have caused the ground to swell whilst the extended early spring dry period will cause shrinkage with the range of movement in soil conditions over the winter/spring period being significant.
Whilst building movement, particularly in older properties can occur on a regular basis and much of this would be seasonal. It is highly likely that progressive and more substantial movement will occur, particularly on more modern properties.
For those who have properties founded on shrinkable soils, extreme weather conditions can create nervousness particularly when cracks start to appear. Householders should be aware of the weather conditions and keep an eye on areas where movement is susceptible.
Older properties tend to be founded on shallower foundations and as such, are more vulnerable to movement from changes in moisture content of the soil. Depending upon the type of property, movement will have a lesser or greater affect on the above ground structure. Older period timber frame properties will move but with line based mortars and a ‘flexible’ timber frame movement can be readily accommodated particularly if it is seasonal and non progressive. Routine maintenance and repair is likely to be all that is required, although if movement continues beyond what would normally be considered seasonal then such movement may have become progressive and potentially more serious.
In later properties, up to the late 1970s, foundation depths may be relatively shallow, say up to 600mm and whilst limited seasonal movement could be accommodated, structures are more likely to be masonry and less flexible and any greater movement will become immediately apparent.
More recent properties with much greater depth foundations (1m or above) are less likely to be affected by localised ground movement but are still potentially vulnerable from outside factors such as significant trees or defective drains or water services.
If building movement becomes apparent then an inspection will be necessary to identify the likely cause and whether or not it is considered to be progressive and/or significant. An inspection will take account of a number of factors relating to the property, its construction, its immediate environment and other relevant factors such as water services, trees, drains and the like.
Should you experience building movement in the property, please contact us via the enquiry form or call us and we can arrange an inspection for you.
Attached are a series of photographs relating to building movement.