Britain's worst subsidence hotspots are in London and the south east, according to analysis of subsidence claims by Direct Line home insurance.
Even Big Ben has a little bend. Documents recently published by parliament show that the top of its gilded spire is about one-and-a-half feet (nearly half a metre) out of line. The tower has been slightly off centre since it was built in the 19th century. Like many old buildings its position has been shifting imperceptibly for years as the ground beneath it subsides.
London and the south east suffer more from subsidence than the rest of the country because the soil in these regions contains more clay, which is particularly sensitive to changes in moisture.
With repairs from subsidence possibly running into thousands of pounds, householders are advised to take some preventative steps.
Soil volume can change by being too dry. A hot, dry summer can result in a reduction of soil volume. When this changes, the building can be damaged by tapering cracks. Whilst there is not a lot that can be done about this, householders need to be vigilant and pay close attention to the outward appearance of their home.
It's not just nature that can have an effect on subsidence. Other research from Direct Line found nearly 20% of households are planning major building work or an extension to their homes in the next year. This could put more properties at risk of subsidence if these extensions are not built with deep foundations or too close to existing trees.
Rob Warner, head of risk modelling at Direct Line home insurance, explains: "Do not panic if you suspect you have subsidence. You should act quickly by calling your insurer immediately. If you are concerned about the trees on your property do not make any rash decisions to cut them down. Look at what kind of tree it is, how far away from the house it is and whether they are protected by local conservation. Good property maintenance such as looking after your drains can also help, as this could erode the soil surrounding the house."
Top ten postal districts for subsidence in London