30 percent roof rule 6

https://kilo-wiki.win/index.php/How_Long_Do_Roofs_Last_in_Austin%3F_A_Homeowner%E2%80%99s_Guide_to_Lifespan_and_Repair_Decisions

The 30 percent roof rule suggests that no more than 30% of your total roof area should have equipment like solar panels or HVAC units, to maintain structural integrity, allow for maintenance access, and avoid shading issues that reduce efficiency.