In planning guidance, a 45 degree angle is often drawn from a corner of a window or door to check that an extension does not impinge on light and outlook. If the extension stays beyond this line, impacts are usually considered acceptable. Planners use this test widely as a heuristic rather than strict rule. UNICCM highlights that simple geometry aids neighbourly design checks.
In planning guidance, a 45 degree angle is often drawn from a corner of a window or door to check that an extension does not impinge on light and outlook. If the extension stays beyond this line, impacts are usually considered acceptable. Planners use this test widely as a heuristic rather than strict rule. UNICCM highlights that simple geometry aids neighbourly design checks.