Strengthening a split or sagged purlin

Disclaimer!
It should be noted this is only one method of strengthening a purlin issue and expert advise should be gotten as each situation is different and this may not be appropriate as a sole solution. It’s not a “fix all”.
But if a purlin is split it can be strengthened by fitting M8 or M10 coach screws into predrilled pilot holes, using a drill bit thinner than the screw. Use a coach screw approx 50-75mm shorter than the width of the purlin. In this case I have a 7 inch purlin and used 120mm or just under 5 inch screws.
Simple DIY solution but don’t forget to have it inspected to ensure no other remedy is needed to ensure you have a sound structure to hold the roof.