Property companies state that land values follow house prices and that a developer assesses what new build house price is achievable in any particular location with reference to prices and sales rates in the second hand market and on nearby comparable new build sites. At a basic level (assuming no affordable housing, S106 or CIL), they then multiply that new build house price by the number of homes to be built on the land and to arrive at the gross development value (GDV) of the site. The underlying value of the land is then the GDV less the cost of development and less an allowance for profit.