From top to bottom
Definition 1 of 2
Pro Tip 1/3Thorough Inspection
Use when describing a detailed review or scrutiny of something, not just a glance. 
The detective examined the crime scene from top to bottom.
Pro Tip 2/3Complete Cleaning
Implies a meticulous and detailed cleaning process, leaving no part untouched. 
Before the guests arrive, I'll have the house cleaned from top to bottom.
Pro Tip 3/3Figurative Use
Can be used to mean reforming all parts of an organization, system, or plan. 
The new management restructured the company from top to bottom.