Carpentry 2: Intersecting Roofs Part A & B
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Name the 2 basic types of intersecting roofs.
What type of rafter is required where intersecting roof surfaces meet?
Identify the types of valley rafters needed to frame an unequal span intersecting roof.
Supporting and supported valley rafter
Valley rafters use the _______ slope gain factor. All other rafters for the intersecting roof use the ________ slop gain factor
45 degree; 90 degree
The supporting valley rafter is similar to what other rafter?
Has the same horizontal run as the major hip and therefore the same line length.
When laying out a valley rafter, you use the same framing square numbers as for what other type of rafter?
What is the shortening at the upper end of a supporting valley rafter?
1/2 diagonal of major ridge
What is the shortening at the lower end for either valley rafter?
Full diagonal thickness of fascia
Is a single or double cheek cut required at the lower end of the valley rafters?
Either could be used.
Does the supporting valley rafter need to be backed?
- A portion of the supporting valley is above the plane formed by the top edge of the common rafters and this needs to be backed, like the hip rafter.
- It extends from the intersection of the supported valley to the ridge.
What determines the amount of wood above plate for a valley rafter birdsmouth?
Same as for common rafters.
The supported valley rafter is similar to what other rafter?
Has the same horizontal run as the minor hip and therefore the same line length.
What is the shortening at the upper end of a supported valley rafter?
1/2 thickness of supporting valley rafter
What type of cut is made at the top of the supported valley rafter?
Valley jack rafters extend from the _____ to the _______
ridge; valley rafters
On a minor roof, a valley jack rafter is 1700 mm from the intersection of the valley rafters. What is its run?
What information is needed to calculate the common difference for valley jack rafters?
- Slope gain factor
- OC spacing of the rafters
What is the lower end shortening of a valley jack rafter?
1/2 diagonal thickness of valley rafter
The upper end of a valley jack rafter is identical to the upper end of what other type of rafter?
Valley cripple jack rafters extend from the _____ to the _____
supporting valley rafter; supported valley rafter
The run of a valley cripple jack rafter is equal to what dimension?
Twice the distance from the intersection of supporting and supported valley rafters
What type of cut is made at the ends of a valley cripple jack rafter?
Single cheek cut at opposite angles
The upper end of a valley cripple jack is similar to what other type of rafter?
Upper end of a hip jack rafter
The run of a hip-valley cripple jack rafter is equal to what dimension?
- the offset of the minor roof (the dimension from the outside corner of the major roof to the minor roof).
- This is because the offset is one side of a 45 degree triangle, whereas the run of the hip-valley cripple jack is the other side.
What shortening is required for the hip-valley cripple jack at the upper and lower end?
- Upper end: 1/2 diagonal thickness of hip rafter
- Lower end: 1/2 diagonal thickness of valley rafter
What type of cut is made at the ends of a hip-valley cripple jack rafter?
Parallel single cheek cuts
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