| TECHNOLOGY |
that uses DNA fingerprinting to help insurers identify trees that are causing houses to sink into the ground. The company will work for tree specialists and building surveyors as well as insurance firms. Disputes often can last several years. When two trees of the same species are involved, finding the guilty one can be very difficult. That's because their roots--which can grow underneath the house and cause the subsidence--may stretch for several meters in different directions. "Houses built on clay are particularly at risk from subsidence, and more so in times of drought. Tree roots suck water out of the ground, which causes the clay supporting the house to dry out and contract. Co get involved when neighbors own trees whose roots are equally likely to be spreading under the sinking house. We try to establish which tree is to blame and thus indicate which insurance company should pay out." Co. "is particularly significant for insurance companies or building surveyors acting for people who live in London and the south of England or affluent areas generally, where house prices tend to be much higher and claims are therefore much bigger." The analytical problem is not so tough with trees of different species in the same area. You can easily tell the difference between the roots of oak and chestnut trees, for example. In difficult cases--trees of the same kind in the same area-- Co Hale start by sampling suspected trees and the root that's causing the subsidence. Then they create a DNA bar code that can be used to compare the samples. If that fails, they look for differences in the lengths of DNA fragments. Finally, they resort to DNA sequencing. A full analysis takes about two weeks
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