Shadow diagrams are required mostly when you are adding a second storey. They show the extent of overshadowing for neighbouring properties.
For residential alterations the rule of thumb is to make sure that north-facing windows to habitable rooms of neighbouring dwellings do not have sunlight reduced to less than 3 hours between 9.00am and 3.00pm on 21 June.
Some councils also require shadow diagrams for spring equinoxes – around 20 March and 22 September. When there are concerns about overshadowing windows the council may also require vertical shadow diagrams shown below.
We establish how much sun your project will block for your neighbours and can offer options to improve the design and your chances of approval.
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