Daylight Check

See whether your house extension would take too much daylight from the windows next door, using BRE 209's sky component and 25° and 45° tests.

Draw the houses, the neighbours' windows and your extension. For each window you get its vertical sky component before and after, the 25° and 45° tests, and a verdict: Pass, Borderline or Fail.

Draw your plan

How Daylight Check works and how it was checked