What screws for roofing sheets?

[kez6]

I am getting ready to paint the beams holding the roofing sheets above my deck. The external beams have a thin metal covering that is coming away from the beam in parts... the screws are missing. 

Wondering what screws to replace with. My understanding is not galvanised... but which type?

 

[JacobZ]

Hi @kez6,

Without knowing what metal the flashing is, your safest option is to use stainless steel screws like these 25mm Stainless Steel Pan Head Screws with a Nylon Washer. 

Stainless steel is non-corrosive, but it can cause galvanic corrosion on the metal strip if the metals are reactive with each other. Adding a nylon washer will keep the screw and the metal strip from having a large contact patch, which will greatly reduce the risk of galvanic corrosion.   

Let me know if you have further questions.

Jacob