Measuring a room
Measure length and width wall to wall at floor level, and the height from the floor to the ceiling, in metres.
For each door and window, measure its width and height, and for a window the height of its sill from the floor. Doors are taken off the baseboard too.
A room that is not a rectangle can be split into rectangles, each added as a room.
How the quantities are counted
Floor and ceiling: length × width. Walls: the perimeter × the height, minus the doors and windows.
When a wall is tiled up to a height (a bathroom to 2,1 m, for example), the tile covers the walls up to that line and the paint the walls above it; each door or window is split at the line.
Baseboard: the perimeter minus the doors. Each finish adds its waste, paint is multiplied by its coats, and the units are rounded up once, after adding all the rooms.