Subsidence and the drought 27 April 2012 Miriam Ibbotson Right http://www.cetamail.co.uk/files/subsidenceandthedrought_lrg.jpg A couple of weeks ago the Environment Agency announced a drought across much of the south and east of England. Hose pipe bans were issued by seven water companies and are set to remain in place, despite the recent heavy rainfall. The link between drought and subsidence Drought causes ground water levels to fall and the soil underneath a building to dry up. If your house is built on clay soil, the clay shrinks and pulls on the foundations causing cracks and other issues. The problem can be worsened by the presence of nearby trees. As their roots suck the last remaining moisture out of the soil, further clay shrinkage can result, causing even more subsidence. What's more, a tree's roots can extend much further than its actual height; for example the roots of a typical willow, with a height of 25 metres at maturity, can be up to 40 metres long. Note: as well as being caused by drought, subsidence can also occur as a result of too much water, in the form of leaks from pipes. This can wash the soil away from the foundations. Unlike drought-induced subsidence which tends to affect houses built on clay soil, this form of subsidence is most likely to occur with sandy, gravel-based or chalky soils. Spotting the problem As a landlord you should be paying regular inspection visits to your property but it's a good idea to encourage your tenants to report any problems as and when they occur. Look out for the following signs: New cracks in the plasterwork or exterior brickwork, or a growth in existing cracks. Watch out for wide cracks - say, wider than the thickness of a fifty pence piece, or cracks that are wider at the top than they are at the bottom. Windows and doors that don't shut or open properly any more. Ripples in wallpaper that aren't associated with damp. If any of these signs do appear, you should contact your insurance company as soon as possible. They will get a specialist to carry out inspections such as soil and drainage surveys and thus make an official "diagnosis" of what's causing the subsidence. They may also want to monitor the situation for several months to see just how bad the problem is and whether it's getting worse. Sorting out your subsidence Once it's been established that subsidence is indeed occurring in your property, you will obviously need to deal with whatever has caused the subsidence, such as fixing a leaking pipe/water main, before filling up any cracks in the property. In about ten percent of cases, this won't be enough, and underpinning the property's foundations will be necessary. In such cases putting the subsidence right can cost anything up to £50K, although the typical insurance claim is around £8K. You can expect to pay an excess of about £1K. Are trees to blame? When subsidence is discovered, many insurance companies are now insisting that the owner cut down any trees growing in the garden of the affected property. There have even been court battles between insurance companies and local authorities, about the alleged subsidence that street trees have caused to homes. If your insurance company tells you to cut down a tree growing on your property, you should get professional advice from a professional arboricultural consultant before doing so. Sometimes tree removal can actually make the subsidence problem worse; there are other techniques, such as pollarding, which will stop the roots from spreading and causing more damage. The Royal Horticultural Society has advice and further reading on what to do about trees and subsidence - you can read more here: http://apps.rhs.org.uk/advicesearch/Profile.aspx?pid=225. The Arboricultural Association has a directory of consultants across the UK, which is available here: http://www.trees.org.uk/find-a-professional/Directory-of-Tree-Consultants#directory . Prevention of future subsidence Obviously you can never be 100% sure of preventing future subsidence but there are steps that you as a landlord can take to help minimise the risk. As already mentioned, paying regular inspection visits (with advance notice to your tenants of course) is an essential part of this. You should also check drains for leaks and if you're tempted to plant trees, avoid placing them too close to the property or to any underground drains. Consider any neighbouring properties too, because you don't want to end up with a claim against you a few years down the line!