Gordydee

Hi folks, first post here. I’m needing some help on what the best way to fix some broken loft roof boards is. There are quite a few sagging down and previous owner has tried to support them up with wooden battens before, but they’re too light weight. My plan was to cut out the bad sections of boards between the trusses and secure new sections of similar fibre board with bracing of 3x1” battens across at 90 degrees between the trusses. I know the best way would be to rip the whole lot down and put the likes of Kingspan insulation and sheet it but it’s a suitable fix for now I’m looking at without doing any real major work like taking the whole roof off. The areas of board that are just sagging down and not broken I was just going to push up and reinforce with decent wood secured through the trusses at reasonable intervals. Also, I’m not sure where I can get this fibre board from? It’s around 12mm thick. I’ve included some pics. Apologies if they’re not that great. Appreciate any ideas or thoughts on how to go about this.