Roof Framing Definitions
The following is a listing of right triangle and roof framing terms to assist you in understanding how to use your Construction Master™ roof framing functions.
Related functions:
Definitions:
-
Rise: The vertical distance measured from the wall's top plate to the
top of the ridge.
-
Span: The horizontal distance or full width between the outside
edges of the wall's top plates.
-
Run: The horizontal distance between the outside edge of the wall's
top plate and the center of the ridge; in most cases this is equivalent
to half of the span.
-
Pitch: Pitch and slope are synonymous in modern trade language.
Pitch/slope of a roof is generally expressed in two types of measurement:
1) Ratio of unit rise to unit run* - 7/12 or 7 Inch
2) Angle of rafters, in degrees - 30.26°
*The unit rise is the number of Inches of rise per Foot (12 Inches) of unit run. The unit run is expressed as one Foot (12 Inches).
-
Plate: The top horizontal wall member that the ceiling joist and
rafters sit on and fasten to.
-
Ridge: The uppermost point of two roof planes. This rafter is the
uppermost rafter that all Hip, Valley, Valley Jack and Common rafters
are fastened to.
-
Rafters: Rafters are inclined roof support members. Rafters include
the following types:
-
Common Rafter: The Common connects the plate to the ridge
and is perpendicular to the ridge.
-
Hip Rafter: The Hip rafter extends from the corner of two wall
plates to the ridge or King rafter at angle other than 90°. The Hip
rafter is an external angle of two planes.
-
Valley Rafter: The Valley rafter extends from the corner of two
wall plates to the ridge or King rafter at angle other than 90°.
The Valley rafter is an internal angle of two planes.
-
Jack Rafters: Rafters that connect the Hip or Valley rafter to the
wall plate.
-
Irregular Hip/Valley Jacks: Jack rafters found in dual pitch or
"Irregular" roofs.
-
Regular Roof: A standard roof where the Hips and/or Valleys run at
45° and have the same pitch/slope on both sides of the Hip and/or
Valley.
-
Irregular Roof: A non-standard roof where the Hips and/or Valleys
bisect two different pitches/slopes, or have "skewed wings" or irregular
Jacks.
-
Rake Wall: A gable end wall that follows the pitch/slope of a roof.
-
Plumb: Vertical Cut. The angle of cut from the edge of the board
that allows the rafter to mate on the vertical side of the ridge rafter.
-
Level: Horizontal Cut. The angle of cut from the edge of the board
that allows the rafter to seat flat on the wall plate.
-
Cheek: Side Cut(s). The angle to cut from the SIDE of the Jack
rafter to match up against the Hip or Valley rafter, usually made by
tilting the blade from 90°. Jack rafters typically have one Cheek cut.
If there is only one pitch (no irregular pitch), the angle will be 45°. If there are two pitches, each side will have a different Cheek cut for
the Jack rafter and the angles will total 90°.
-
Incremental Adjustment: The difference in rafter length from one
rafter to the next.