That wouldn't be a standard exclusion. I presume you are referring to a subsidence claim. most insurers have a computer database where they put in yours postcode and it tells them whether your property is at low, medium or high risk of subsidence. If it is medium or high they will probably ask you to fill in a questionnaire which would ask questions about trees within so many metres from your house, amongst other things. If you are unsure check your policy schedule to see if it contains such an exclusion. I would doubt it. Normally it's case that insurers would decide to give subsidence cover or not give it, depending on the risk. Or they may decide to give cover with an increased excess. If you have a large tree Near your property I would get advice on it. As a rough guide the roots are usually as long as the trees is high,and different trees have different water demands so some are more of a risk than others.