Roof framing calculator — geometry, rafters and workshop data in one workflow.
A roof framing calculator should do more than return one rafter length. A useful framing workflow connects roof dimensions with rafters, hip and jack rafters, support elements, workshop cards and cutting documentation.
What should a roof framing calculator calculate?
At a minimum, the calculation starts with the roof span or run, roof pitch, ridge position and overhang. From that geometry you can derive common-rafter lengths and the vertical roof rise. Hip roofs add diagonal members, jack rafters and more complex spacing relationships.
A practical framing tool should then connect the geometry to real elements rather than stop at a single number. That means element IDs, sections, lengths, notches, end cuts, openings and the information needed to prepare the timber.
Core geometric relationships
For a simple symmetrical gable roof, the common rafter is the hypotenuse of a right triangle:
rafter length = √(run² + rise²)
If pitch is expressed as rise per unit run, then rise = run × pitch ratio. The geometric ridge height is the same vertical rise measured from the wall-plate level to the theoretical ridge line.
Why a full framing model matters
- the same roof dimensions feed the 2D drawing and the 3D model,
- rafter positions stay linked to openings and supporting elements,
- cutting lists use real elements rather than disconnected calculations,
- workshop cards can point to the same element IDs used on drawings and PDFs.
Roof framing calculator vs rafter calculator
A rafter calculator answers a narrower question: how long is one rafter and what is its slope geometry? A roof framing calculator covers the relationships between many elements across the roof. For a hip roof that includes common rafters, hip rafters and jack rafters; for supported systems it can also include purlins, posts, collar ties, tie beams, braces and base beams.
How Krokwio approaches the workflow
Krokwio v1.0.0 keeps the project geometry, framing configuration, 2D/3D views, element cards and documentation in one workspace. The application focuses on gable and hip roofs and lets the user build a framing configuration from the modules needed for the project.
Related: Rafter Calculator, Gable Roof Calculator, Hip Roof Calculator.
Turn roof geometry into workshop-ready information.
Use one project for geometry, 2D/3D views, element cards, cutting data, PDF documentation and QR identification.
Roof framing workflow: from measurements to workshop output
Begin with the building footprint, ridge position, roof pitch, support locations and overhang. Check the rafter geometry before adding openings and supporting members. Keep the same measurement reference throughout the model: a horizontal run is not a sloping rafter length, and a theoretical line is not necessarily a timber cutting dimension.
Example: a symmetrical gable roof
For a 8 m building span and 35° pitch, the horizontal common-rafter run is 4 m, before overhang. The theoretical slope length is 4 / cos(35°), or approximately 4.88 m, measured along the reference line. Actual workshop lengths and cuts depend on ridge, support and overhang details.
Related roof-framing calculations
Rafter length calculator · Hip roof geometry · Birdsmouth cut layout · Roof framing cutting list
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