Terms used in a pitched roof

Terms used in a pitched roof

• Ridge: the horizontal line at the top where two sloping surfaces meet.
• Hip: the inclined line (external angle) where two adjacent sloping surfaces meet; the hip rafter runs along it.
• Valley: the inclined line (internal angle) where two slopes meet to form a depression; it drains water.
• Eaves: the lower edge of the roof that projects beyond the wall face to throw water clear of the wall.
• Purlin: a horizontal member running parallel to the ridge across the principal rafters/trusses, supporting the common rafters.
• Rafter: an inclined member running from the eaves to the ridge on which battens or boarding are fixed (common rafter, principal rafter, hip rafter, jack rafter).
• Batten: a thin wooden strip fixed over the rafters on which tiles or slates are hung or sheets are fixed.
• Rise: the vertical height from the wall plate (eaves) to the ridge.
• Span: the clear horizontal distance between the supports (inner faces of walls).
• Pitch (slope): the ratio rise/span, or the angle of the slope with the horizontal.
• Gable: the triangular portion of the end wall between the sloping edges.
• Wall plate: a timber/RCC member laid on top of the wall to spread the load of the rafters or trusses.
• Tie beam: a horizontal member joining the feet of the rafters to resist the outward thrust.
• Verge: the edge of the roof at the gable end.
• Barge board / fascia: a board fixed along the verge/eaves for appearance and protection.
• Cleat: a small block fixed to the principal rafter to prevent the purlin from sliding.

Figure

              ridge
               /\
              /  \    <- rafter
     rise ->  /    \
             /      \
   eaves ->_/________\_<- eaves
         wall plate  wall
         |<-- span -->|

 PLAN OF A HIPPED ROOF (L-shaped)
  +-----------------------+
  |\        ridge        /|
  |  \_________________/  |  <- eaves (all round)
  |  /                 \  |
  |/  hip           hip  \|
  +--------+     /--------+
           | \  / valley
           |  \/   |
           |  |ridge
           |  |    |
           +-------+

The hip, valley, ridge and eaves are lines on the roof surface; rafters, purlins and battens are the frame members that carry the covering.