I'm in the process of purchasing a semi-detached and the home buyers survey has shown up a problem with the roof. In 2004, the vendors had foam applied to the underside of the roofing tiles to create a watertight seal in the lofts of both sides of the semi - they owned both - and still do. The house is dated as 1870. The guarantee on this foam is 25 years. There are now missing and chipped tiles on the roof. The surveyor says that condensation will form in the loft and cause problems and it would be best to have the foam removed. This means completely replacing the roof. An independent roofer has stated that as the job will take 2-3 times as long, it will be much more expensive and that I will have difficulty in finding a roofer who would want to do the job - if they have any experience of working with this foam. Does anyone have any experience of removing a roof with this foam treatment or any remarks to make that might help me decide whether to continue with my offer on the house?