Often valuations will be based on the previous sale price of a property multiplied by the percentage growth of local properties since. This can be factored against what similar properties have sold for recently to come up with an estimate. This can give an idea of value, but is not a very accurate way to do a property valuation. An expert valuer will normally be far more accurate. At Cox & Co we have sold a lot of properties and we normally have a gut feel for the value as soon as we have walked around a house or commercial building. We do a lot of research to back up our valuation too.