45 degree angles test for assessing overshadowing

The effect of a proposed extension on daylight can be assessed using the 45 degree angles tests to indicate where a proposal is likely to overshadow neighbouring properties. The tests take into account the location of the neighbouring property's/properties' closest main habitable rooms (i.e. bedrooms, living rooms, dining rooms or kitchens) and provides a tool to help assess the loss of light as a result of proposed extensions to the front and rear of a residential property. In addition to the consideration of the neighbouring property/properties, it is good practice to also apply the tests to the existing windows of the property being extended.