Desktop surveys are no longer a priority for lenders, as spray foam insulation has become a major problem. Spray foam insulation can block much-needed air circulation when installed incorrectly, which can lead to timber decay and lenders consider this a major structural risk. Desktop valuations don’t take into account that there may be spray foam insulation on your property’s roof space. It’s a simple mistake that can cost your new homeowner thousands of pounds in replacement costs. You can file a complaint against a lender via the Financial Ombudsman service (FOS).