Fink roof truss bracing

7 Nov 2018
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United Kingdom
I've decided to brace my roof before raising the boards on plastic legs in the central area and adding top-up insulation throughout. It came up in the survey (I'm aware of the justified criticism) and it's not something I want to remedy before selling and I hope it's 'best practice'. Anyway, I wanted to put my research and plans here to help others and for the pros to correct.

It's a late 1960's semi with a span of 8m and width 7m. It's the common 'fink' roof truss (i.e. \/\/) at 400mm spacing and there's a 4x2" timber tieing all the bottom chords together in the middle along the full width (called a bottom chord runner?).

Useful threads...
Reading I found useful...

My plans...
Chevron bracing - not required because my span is not over 8m
Longitudinal bracing - one at ridge node, two at rafter nodes, two at bottom chord nodes. Leave 25mm gap to node (allows space for diagonal braces). I assume the ones at the bottom chord nodes aren't needed because of the bottom chord runner?
Diagonal bracing - four braces fixed to underside of rafters running from gable end eaves to apex (a big X) - keep angle at 45 deg +/- 10 deg. Other possibilities are diamond or chevron patterns (see Appendix 7.2-B of the last PDF). Woody suggests just two braces from apex to eaves one side and eaves to apex the other (parallel braces rather than an X, diamond or chevron) in the first thread above but I can't see this suggested in the reading. A gap of one truss between bracings is allowed. I've ignored fixing to the wall plate cos I assume I can't get in close enough to fix it.
General stuff - 97 x 22mm treated timber screwed (4.0 x 60mm sufficient?) instead of nailing, two screws per truss. Overlap braces by at least two trusses. If crossing diagonal braces cut one brace and splice with 600mm timber. Abut all braces tightly to gable/party walls. Fix the diagonal braces first.

I hope this helps others, thanks.
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