A roof for a building comprises a ridge beam for defining an upper edge of the roof, and a first eaves beam for defining a lower edge of the roof. The roof further comprises a first panel connectable to both the ridge beam and the eaves beam, being capable of spanning the distance therebetween and extending over at least a first portion of the area of the roof. In addition, the roof comprises one or more retention structures positionable relative to the first panel and one of said beams and configured to clamp said panel against the other of said beams.