Subordinate design principles for extensions and alterations

It is important that an extension or alteration does not upset the balance of a property, particularly the front elevation. It is also good practice to reinforce the existing form and proportions of the host building. An extension or alteration should therefore be subordinate to the existing property in order to reduce the visual impact of the additional element. Subordinate design means design that allows the existing building to remain dominant in terms of massing, height and position. The height, width and general size of an extension or alteration should therefore be smaller than the existing property, and achieve appropriate scale, proportion and balance. Ideally, the depth should be no greater than the depth of the side elevation of the existing property (subject to other considerations such as amenity space, overshadowing etc), and, eaves should be no higher than eaves of the existing dwelling.