- Roof: The roof of a building is the covering on top of it that protects the people and things inside from the weather.
- Slope: A slope is a surface that is at an angle, so that one end is higher than the other
- The roof needs to be sloped to remove rain, snow, debris, etc.
- The steepness of the slope of the roof depends on how much it has to "remove" throughout the year. For example: Roof lines in Switzerland or Revelstoke, BC (areas with large amounts of snow) need to have a steep slope so that the snow can easily slide off. You want to remove the snow/rain so that it doesn't add excess weight on the roof which could cause it to collapse; or pool and cause leaks.
- Roof Pitch: The pitch of a roof is its vertical rise divided by its horizontal run, what is called "slope" in geometry. In the imperial measurement systems it is typically expressed with the rise first and run second. The run is denominated by the number 12, giving a ratio of how many inches of rise or fall there are to each 12 inches (one foot) of run. For example, 3:12, 4:12, 5:12, and so on.
- Eaves or Roof overhang: The eaves are the edges of the roof which overhang the face of a wall and, normally, project beyond the side of a building. The primary function of the eaves is to keep rain water off the walls and to prevent the ingress of water at the junction where the roof meets the wall. The eaves may also protect a pathway around the building from the rain, prevent erosion of the footings, and reduce splatter on the wall from rain as it hits the ground. The secondary function is to control solar penetration as a form of passive solar building design; the eaves overhang can be designed to adjust the building's solar gain to suit the local climate. The eaves overhang may also shelter openings to ventilate the roof space