A ridge board is a horizontal board running along the peak of a roof where opposing rafters meet, providing a connection point and nailing surface for the rafters but generally not bearing significant structural load itself in a conventional roof design with ceiling joists present.
In this common configuration, the actual structural resistance to the rafters’ outward thrust comes from the ceiling joists acting in tension, connecting the base of opposing rafters together, rather than from the ridge board at the peak.
Because the ridge board’s role is primarily to provide a consistent connection point rather than carry major structural load, it can typically be sized somewhat more modestly than a true structural ridge beam would require.
What Does a Ridge Board Involve?
- A horizontal board at the roof’s peak
- Connection surface for opposing rafters
- Reliance on ceiling joists for structural thrust resistance
- Modest sizing compared to a true structural ridge beam
Why Are Ridge Boards Important?
By providing a stable, consistent connection point at the roof’s peak, a ridge board simplifies the construction process, giving carpenters a straightforward reference line to frame rafters against from both sides of the roof. Because this element isn’t typically load-bearing in a conventional roof design, it requires less structural sizing consideration than the ridge beam needed for a cathedral ceiling without ceiling joists.
Confusing a ridge board with a structural ridge beam during a renovation, particularly one converting a conventional attic to a cathedral ceiling, is a genuine and potentially serious mistake, since removing ceiling joists without providing an actual structural ridge beam to replace their function can allow the roof to spread.
Ridge Board vs. Ridge Beam
A ridge board serves as a connection point without significant structural load, relying on ceiling joists for thrust resistance. A ridge beam actually carries structural load from the rafters, requiring dedicated support and used specifically where ceiling joists aren’t present.