Draw a sketch of the room where you will install coving. Leave enough space on the diagram to add measurement figures.
Measure the length in between all corners of the room with a tape measure. Write down each measurement on the corresponding wall in your diagram.
Place a 360-degree adjustable protractor against each corner, both inside and outside.
Move each side of the protractor until each lay flush on opposite walls in the corner. Write down the degree measurement on your diagram.