Your measuring of the knee wall height – A
The knee wall height is the distance between the floor and the start of the sloping wall (marked “Knee wall” on the figure below).
Your measuring of the angle – B
It is the angle in degrees between a horizontal line (= the dottet line equal to the floor) and the sloping wall, typically between 30 and 60 degrees.
Use a Smartphones with a standard setup with protractor (and compass). Hold your smartphone horizontally (showing 0 degrees) and then move the phone until it follows the sloped wall. Do not tilt the phone – the top and bottom of the phone must be parallel to the end wall. Read the degree.
Find your protractor for smartphone here:
Download free VELUX protractor for smartphone – Iphone (App store) or Android (Google play) – tap icon.
- You can also print a paper version of an angle meter here. Follow the instructions on paper