Coupled roof
A coupled roof is a pitched roof where ceiling joists tie the rafter feet to resist outward thrust, as opposed to a roof carried on a structural ridge beam.
Ask Chalkline about this →A coupled roof is a conventional pitched roof in which the opposing rafters are tied at their feet by the ceiling joists, forming a triangle, so the joists resist the rafters’ outward thrust. It contrasts with a roof carried on a structural ridge beam.
In a coupled roof the opposing rafters lean against each other over the ridge. Left to themselves they would push out at the feet and spread the walls. The ceiling joists run across the bottom of the triangle and act as ties, holding the rafter feet together and stopping the spread. The rafters, the ceiling joists, and a (non-structural) ridge board work together like a truss: the ridge board just aligns the rafters, it does not carry them.
The alternative is a ridge-beam roof, where a structural ridge beam carries the rafter loads down to posts, so the rafters bear on the beam and do not thrust outward. That is the system used for raked or cathedral ceilings, where there are no ceiling joists to act as ties.
For a builder the key point is to know which system you are building, because it changes what is structural. In a coupled roof the ceiling joists are structural ties: you cannot cut, omit, or poorly lap them without the walls spreading and the ridge sagging. If the design calls for a raked ceiling with no ties, it needs a properly sized structural ridge beam, with the rafters and beam designed by the engineer or to AS 1684. Confusing the two, removing ties from what is actually a coupled roof, is a classic cause of spreading walls.
Also known as: Couple roof, close-coupled roof.
Category: Roof framing / Structure.
Related
See also
References
- AS 1684 Residential timber-framed construction, Standards Australia (verified 2026-06-01)
Last updated: 2026-06-01. Verified: 2026-06-01. Quarterly review for currency.