They often receive intense heat from the setting sun. Next, shade the south walls, because they receive many hours of sun each day. Direct sun strikes east-facing walls only in the morning, so they would be last on the list. Shading the north side of your home is unnecessary. It just cuts down on light without blocking much heat.
Heat bombards the roof all day long, but the roof is also the most difficult to shade.
The Heat Blockers section lists other methods for reducing heat gain through your roof. Shade Trees Trees can shade nearby walls and windows. When they grow tall they will shade a part of the roof. They also will shade driveways, sidewalks and patios that can bounce heat to the building. Homes with large windows and walls without insulation will benefit most from shading.