Fixing Gutter support and C section

[Merauke2021]

Hello.
I'm fixing my gutter supports(rusted out badly in places) and looking to do something with C section that has rusted out also.
Any advice would be appreciated.

Our house has a roof that is as follows:

• The house is a rectangular Besser block construction.
• 
• Running across the top of these blocks(along the short side of the rectangle) are cement strips inside C section tin.
• Photo below are cement strips seen from inside the house.
• 
• On top of these cement strips is a huge block of cement. The huge block is the roof.
• 
• Running around the outside of the house(on the edges of the cement strips) is a steel C section. It’s dimensions are – 14.3m along the length of house and 8.5m along width of house(approx – didn’t go to exact cm). The measurements of the C section are 35mm x 100mm. The C section is approx. 3-4mm thick.
• This steel C section is fixed to the top of the roof by steel fixtures(4 along the long side and 2 along the short side). It is also welded at the corners. Ie long section and short section meet and are welded together.
• 
  • This steel has facia board attached to it and in turn the guttering.
• Issues:
  
  • The steel C section is badly rusted. In sections there are holes where it has rusted through.
• 
  
  
• The tin C section has rusted away in places leaving just the cement strip(I’ve cut these back with a grinder). The width of the C section is approx. 188mm.
• 
• The tin C section was painted but is flaking away in some places.
• 
• Solutions at this stage:
• I was going to grind the rust away from the steel C section and try and bring it back to bare metal. This was hard because as per photo above the metal isn’t even so it’s hard to get the divots. I was going to get steel putty and fix the holes. Then paint it with primer and then rust proof paint. Have now decided to look at removing the steel and replacing it with new, rust proof steel.
• The tin C section with cement strips in it – at this stage my thoughts are to cut the tin where it is rusted. Cut it in a straight line at right angles to the cement strip. Buff all of the paint/dirt off the remaining C section. Metal prime it and metal paint it with waterproof paint. Buff the exposed cement strip clean. Seal it with cement primer. Paint it with cement waterproof paint. Buy C section and cut it to fit the missing part of C section that has rusted out/been trimmed off. Fix it into place with some kind of glue/sealant that will keep it firmly fixed in place and keep water out at the same time(don’t know what to use here). Paint over the outside with metal primer and metal waterproof paint.
• thanks in advance.
• Merauke2021