The Rafter Length calculator computes the length of the rafters based on the span, pitch and overhang.![/attachments/e6d25625-da27-11e2-8e97-bc764e04d25f/RafterLength.JPG](https://www.vcalc.com/attachments/e6d25625-da27-11e2-8e97-bc764e04d25f/gable-roof-geometries.PNG)
INSTRUCTIONS: Choose units and enter the following:
- (S) Span or horizontal length of the run (see diagram)
- (P) Pitch of Roof (choose one)
- (oH) Overhang
- (BW) Rafter Board Width (default: 5.5" for 2x6)
Rafter Length (RL): The rafter length is returned in feet. The calculator also returns the Rafter Board Length (BL), which is the length of 2x needed prior to the angle cuts. However these can be automatically converted to other units via the pull-down menu.
The Math / Science
Using the pitch and the span, the initial rafter length is computed. The calculator takes into consideration the 1.75 inches of the ridge board width. There is then an adder for the additional length associated with the overhang.
- Gable Roof Area: This computes the surface area of a gable roof based on dimensions and pitch.
- Trusses Needed for Roof: This computes the number trusses need for a roof including gabled roof.
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- 4x8 Sheathing for Gable Roof: This computes the total surface area of a roof, the number of 4x8s and framing nails needed for a gabled roof based on the length, span, pitch and overhang.
- Gable Roof Sheathing Cost: This computes the number of 4x8 sheets (32 ft² each) needed to cover a gabled roof based on the ridge length, roof span, overhang and the pitch and applies the unit cost of a 4x8.
![](https://www.vcalc.com/attachments/58538bde-d496-11ee-9b96-bc764e203090/trussX.JPG)
- Nails for Gable Roof Sheathing: This computes the approximate number of nails needed to nail 4x8 sheets to trusses or rafters on a roof based on the dimensions of the roof, spacing of nails on the edges and field of the 4x8, and whether blocking or clips are use.
- Purlins for Gable Roof: This computes the total number and length of purlins for a simple gable roof based on the ridge length of the roof, the roof pitch and the span of the roof.
- Metal for Gable Roof: This estimates the metal panels and trim needed for a metal roof for a simple gabled roof based on the roof dimensions.
![](https://www.vcalc.com/attachments/58538bde-d496-11ee-9b96-bc764e203090/Metal-Panel-Screw.png)
- Metal Screws for Gable Roof: This computes the number of special screws needed for a metal roof.
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- Gable Roof Shingle Cost: This estimates to shingle a basic gable roof based on dimensions (length, span, pitch and overhang) and the unit price of a bundle of shingles.
![](https://www.vcalc.com/attachments/58538bde-d496-11ee-9b96-bc764e203090/gable-roof-geometries.PNG)
- Underlayment for Gable Roof: This estimates the cost of underlayment to cover a basic gable roof based on the area of a roof computed from the dimensions (length, span, pitch and overhang) and the unit price underlayment material.
- Roofing Nails for Gable Roof: This estimates the number of roofing nails needed for a common gabled roof based on roof dimensions and wind conditions.
- Rafters for Gable Roof: This computes the total number of rafter boards (roof joists) for a gabled roof based on the ridge length, pitch and span. It also returns the length of the ridge board, and the length and number of rafter ties and collar ties.
![](https://www.vcalc.com/attachments/58538bde-d496-11ee-9b96-bc764e203090/pole-barn-metal-roof.PNG)
- Rafter Length: This computes the length of the rafters based on the span, pitch and overhang.
- Gable Roof Geometries: This computes the length of rafters, pitch and cut angles, soffit and facia base widths of a gable roof.
- Weight of Snow on Roof: This computes the weight of snow on a gable roof based on roof dimensions, depth and type of snow.
Roof Types
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Roofing Calculators