Truss vs Rafter: How to Choose

Cost, Span, Install Speed, Attic Space & Code Rules

A rafter is a single sloping member cut on site with ceiling joists and collar ties added separately; a truss is an engineered triangulated assembly built in a factory and lifted into place as one unit. Trusses routinely span 30 to 40 feet or more with no interior bearing wall, use smaller lumber because the webs share load, and go up in a fraction of the time, which is why most new houses use them. Stick framing wins on additions, dormers, tight sites where a crane cannot reach, and irregular roofs where design changes happen as work proceeds. The decision people regret most is attic space: standard trusses fill the attic with webs that must never be cut, notched or drilled without an engineered repair detail, so if there is any chance of a future bonus room you must specify attic or scissor trusses before fabrication. This guide compares both on cost, span, labour, ventilation and the rules that are not negotiable.