Roof repair of container classroom

Tender description

We have a container that was converted into a classroom, and the roof has rusted in many areas causing water ingress. We patched as many of the rust spots as we could find, and covered the roof with corrugated steel on a wood frame. However the roof is still leaking. The issues are probably stemming from where a log stove chimney goes through the roof, open sides at the ends of the container, possibly lack of flashing along the front of the corrugated steel sheets, and possibly poor overlaps of the corrugated steel sheets. We would like a more thorough job of waterproofing the roof by improving the corrugated steel roof (i.e. flashing all round, including chimney, close end gaps, sealed overlaps etc), and possibly sealing over the rusted areas on the container roof.