Continuous Rafter


The DSP+ program can be used to calculate and design single-span and multi-span rafters as individual components. For the continuous rafter, the wind load assumptions are based on a closed, symmetrical building and for the single-pitch roof rafter, they are based on a closed building with a single-pitch roof. Cantilevers can be defined at the ridge and the eaves.

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Discover now more programs from the section Roof!

  • Softwood
  • Hardwood
  • Glulam
Structural system
  • Straight continuous rafters having an inclination and the same cross-section over several spans without intermediate joints
  • Different span lengths
  • The cantilever can have a different cross-section
  • Projection over the ground plan of the house can deviate from the cantilever geometry
  • Supports sway in the horizontal and vertical direction or restrained. The restraints can be defined as being rigid or elastic
  • Automatic generation of the loads from self-weight, snow, and wind
  • Additional user-defined loads as uniformly distributed loads, concentrated loads, or trapezoidal loads
  • Man loads as well as wind uplift at projections
  • Accidental snow load is optionally available
  • Loads from photovoltaic arrays
  • To reduce the computing time for more extensive systems, various settings are available for the grouping of load cases and load combinations
Design settings

Optionally selectable:

  • Verification of the wind suction resistance
  • Seismic load combinations
  • Hot design
  • As a standard option, only positive deflections are verified on the cantilever (on short cantilevers, the negative deflection is often decisive in terms of calculation, but this is not always desired)

Effective length for buckling and lateral buckling separately for the cold and hot design:

  • Default setting: calculation of the effective length for buckling from the eigenvalue solution of the plane system. Assumption of continuous lateral support with limitation of the maximum effective length for buckling in the rafter plane to 0.9 times the component length
  • Alternatively, setting the effective length to the length of the member, the component or a default value
Connection details


  • Connection with a notch or pole plate
  • Connection with a straight or haunched cleat

Purlin support

  • With birdsmouth joint
  • With nailed cleat
Document file formats
  • PDF
  • Word
  • Printer
  • User-defined output with various setting options for tables and graphics
  • Result graphics with internal forces, stresses, or displacements can be specifically transferred to the output document using the camera button
  • Support reactions are optionally put out for each load case, each action or as min/max values, either for each rafter or per linear metre
Transfer options
  • System transfer to the other Roof programs
  • System transfer to the RSX Frame program
  • Transfer of support reactions to the Continuous Timber Beam program HTM+
  • Transfer of support reactions to the Continuous Steel Beam program STM+
  • Transfer of support reactions to the Timber Column program HO1+
  • Direct interface to the CAD programs from SEMA
Timber construction
  • DIN EN 1995
  • ÖNORM EN 1995
  • NTC EN 1995
  • BS EN 1995
  • PN EN 1995
  • EN 1995

Support resources