Rainfall levels for the whole of 2012 were 15% above average and similar levels of rain over the past decade have led to increased cases of subsidence. It is estimated that some 6.5 million UK homes at risk of shrink/swell subsidence and subsidence has cost UK home owners £3 billion over the last 10 years.
Now experts are warning that a dry summer in 2013 would cost UK home owners over £291 million in damages due to shrink/swell subsidence. Some long range forecasters are predicting a dry and hot July and August.
According to the British Geological Society, the preceding two years of rainfall have a strong influence on ground saturation in any given year. Clay soils swell when saturated but when dryer weather causes evaporation these soils can shrink, crack and cause subsidence in properties.
In the 10 years to 2011 there were two periods of particularly high rainfall which were followed by very dry years. In 2002, 14% more rain fell than in a normal year. This wet period was followed by a very dry year and in 2003, rainfall was down 20% from the average.
Rainfall during 2008 and 2009 was 15% and 8% above average. This long, extended period of high rainfall was followed immediately by a dry 2010, when yearly rainfall was down 16% on the annual average. In the dry years that followed these wet periods, subsidence claims rose by nearly a third on average.
According to Richard Hinton, business development director of property search provider Searchflow, properties built on clay soil are the most likely to be affected.
‘We’ve had a particularly wet couple of years with 2012 the second wettest on record. If the UK has a very dry summer this year it will certainly lead to a surge in subsidence issues for home owners,’ he said.
‘Clay soil is prevalent in the North, London and the South East and properties in these areas are particularly susceptible to subsidence issues. Peace of mind is important for those hoping to buy property in these areas, especially when there has been two years of above average wet weather. Buyers should be asking their conveyancer to check the risks associated with subsidence. There’s nothing more precarious than making the biggest purchase of your life without all the facts in front of you,’ he explained.
He also pointed out that if 2013 turns out to be another wet year for the UK, the issue of subsidence could be multiplied further if 2014 is a particularly dry year.
‘If we have another year of heavy rain, the can will simply be kicked further down the road. Further swelling of clay soils will lead to more acute shrinkage if 2014 is a dry year. Damage from subsidence costs UK home owners more each year than flooding so owners and buyers need to be aware of the risks their properties face from the outset. Otherwise they could be sitting on a ticking time bomb,’ he said.