60 and 45 degree line assessment tool

To help assess the loss of light as a result of a proposed development to the front or rear of a residential property, the 60 degree and 45 degree lines, as shown in Figure 1 for single storey and two storey extensions respectively, will be employed. These lines will be taken from the centre of the closest neighbouring window. It should be noted that where the closest window is located at first floor level it may be more appropriate to consider this against the 60 degree line. The elevations and outline plans of adjoining properties should be shown on drawings, accurately scaled (in metric measurement) to allow proper consideration of this matter.