What actually blocks it
Leaves, a neighbour’s roof, a second storey, and a dense stand of gums all count. The dish does not need a bare paddock. It needs the part of the sky it uses to stay clear. Seasonal growth matters. A winter view and a summer canopy are not the same shot.
How we decide
We look at the app obstruction check and at the building. Sometimes the clear sky is over the house. Sometimes it is further along the roof, or on a fascia that faces the open side. We do not put a dish in a pretty spot and hope.
If the only clear sky is hard to reach, we sort out access before the day, not when the ladder is already up.
What you can check first
Stand where you think the dish should go and look up. If you are under branches, it is probably the wrong place. Photos of the roof and the trees save time. Red Hill and other treed properties are where this question comes up most.