During a hail storm, I've had holes punched into seven flat polycarbonate sheets that are being used as sky lights in a queensland room in one of my IPs. The polycarbonate sheets are 5m long and 100mm wide. The excess on my insurance is too high to bother with (probably), even though I got a quote for over $2400 to fix it! I don't know if the corrugated iron roof spacing lines up perfectly, otherwise I'd just get 6 2.6m corrugated poly sheets, cut them into thirds and put them on top of the roof. I haven't been there yet, so I'm going from memory and from what my dad has told me (he lives down the road). Edit: Now with picture of the roof.