A ridge beam is a structural beam running along the peak of a roof, actually supporting the weight of the rafters framing into it from below, distinct from a simple ridge board that merely provides a connection point without bearing structural load.
This distinction matters enormously in roof design, since a ridge beam requires its own support at each end, typically posts or bearing walls, while a ridge board relies on the rafters and ceiling joists working together structurally instead.
Ridge beams are particularly common in cathedral ceiling designs, where there’s no horizontal ceiling joist system to resist the outward thrust that rafters would otherwise create against the walls.
What Does a Ridge Beam Involve?
- A structural beam, often engineered lumber or steel
- Support posts or bearing walls at each end
- Rafters framing directly into the beam
- Sizing calculated for the roof’s span and load
Why Are Ridge Beams Important?
In a cathedral ceiling design without horizontal ceiling joists to resist rafter thrust, a properly sized and supported ridge beam becomes essential, actually carrying roof load down through its end supports rather than relying on the rafter-and-joist triangle that resists thrust in more conventional roof designs. Getting this beam’s sizing and support wrong can allow the roof to sag or spread over time, a serious structural concern in cathedral ceiling construction.
Because a ridge beam carries genuine structural load rather than simply serving as a connection point, its design typically requires professional engineering calculation, unlike the simpler ridge board found in more conventional roof framing with ceiling joists present.
Ridge Beam vs. Ridge Board
A ridge beam actually supports structural load from the rafters, requiring its own dedicated support. A ridge board serves primarily as a connection point, with the actual structural resistance to rafter thrust coming from ceiling joists rather than the ridge board itself.