Clause 10.3.4 in NZS 3604:2011 Timber-framed buildings doesn’t require diagonal strap bracing in the roof plane if the supporting braced wall frames extend up to the underside of the rafters and the rafters have a sheet ceiling attached directly to their underside. This would only apply where the frames are raked and all walls extend full height and the wall bracing extends to the top plate of all walls under the monopitch roof.
Where supporting frames have level (horizontal) top plates and monopitch trusses attached to form the monopitch roof, the roof requires bracing as if it were a pitched roof. The trusses will require lateral support at right angles to the length of the trusses at the high end, and the roof will also require roof plane bracing and/or roof space braces. The highest end shall be considered to be a ridge line for bracing purposes.
Summarised from BRANZ GUIDELINE Newsletter, October 2014.