Explore framing complexities that result when roofs of two different pitches intersect.
How does roof framing geometry work.
Using i joists requires the same basic understanding of rafter layout and roof design.
One major factor to consider on a hip roof is that there is often very little peak or ridge area at the top of the roof.
This will the first point of the rafter measurement line using the results of your rafter length calculation measure from this point along the rafter measurement.
In order to do roof framing properly it is important to understand the unique shape and dimensions of your roof since these will greatly impact the geometry of the roof frame.
In the following section we ll cover some of the more common roof and rafter terms you ll need.
Generally used for roof framing but i joists are increasingly common see chapter 13 engineered wood.
A sketchup model helps clarify how various rafters and framing components are assembled in an off angle hip and valley configuration.
And the line length measurement from the roof peak to the building wall is the hypotenuse.
Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement.
The two types of roof framing.
The rise or height of the roof at its peak is the altitude of the triangle.
Truss roof framing is cov ered in section 17 4.
Within the roofing industry there are two basic types of roof framing.
If you add an eaves overhang dimension then the amount the rafter sticks passed the wall will be added to the rafter length.
However a four sided roof is usually a hip roof.
Roof framing terms are related to the parts of a triangle.
Learn more about off angle roof framing.
To measure a 10 20 roof pitch place the 10 on the tongue and the 20 on the body.
The run or half the building span is the base of the triangle.
Includes result for hip valley factor slope factor and the roof slope in degrees.
The longer leg of the framing square is called the body and the shorter one leg is called the tongue.
Roof features associated with basic roof framing terms are shown in figure 2 2.
The framing of a basic gable roof is based on a right angle triangle and the various roof framing components fit the triangle.
When you think of a roof that just has a front and a back that is usually a gable roof.
Your work as a builder.
When a piece of lumber is added to a carpenter s square it becomes a right triangle.
Refer to the figure as you study the terms discussed in the next paragraphs.
From one end of the rafter material using a speed square or framing square mark an x in 12 angle on the rafter and cut it measure down y height from the long point of the rafter cut and make a mark.
