Design a Roof Truss – Basics and 3D Planning

The roof truss is the heart of every house. Once you know the basic types and the key timber sections, you can plan a simple structure safely in 3D.

Rafter roof or purlin roof?

In a rafter roof, opposing rafters form a triangle and support each other – ideal for simple gable roofs without internal posts. A purlin roof carries the rafters on horizontal purlins (ridge, middle, eaves) and allows larger spans and roof windows.

Roof pitch and sections

Common pitches are between 30° and 45°. Rafters are often 8 × 18 cm to 10 × 20 cm, depending on span and snow load. Exact sections follow the structural calculation – when in doubt, consult a structural engineer.

Plan in 3D instead of just sketching

With HolzBau 3D you set the floor plan, purlins and rafters to scale, rotate the structure freely in space and export the parts list with all lengths and cutting angles. Your sketch becomes a solid plan.

Plan your roof truss in 3D for free – with parts list and cutting plan.