New warm roof on lean to

[ColdOutside]

I have an existing lean to that is leaking through the underfelt. It’s tiled well but I suspect there isn’t enough fall.

I was hoping to remove all tiles, felt and battens and squeeze in a warm roof without changing the existing lead flashing and existing roof joists.

I was hoping to fit 11mm osb directly to joists then 50mm PIR and then another 11mm osb with a final corrugated metal roof with a underfelt (drip stop) for condensation control.

Does this sound viable?

Would you screw the metal sheet roof all the way through the warm roof to the joists to sandwich altogether or would this compromise the warm roof? How does all the above fix without compromising the warm roof?

 

[markc]

When you look the tiles are almost horizontal so water will be blown up and user the top of tiles quite easily. As for the fixing I would fix fix OSB, insulation and OSB as one fix and then the sheets as a separate fix

[ColdOutside]

So you’d fix through the insulation into the joists? And then fix through metal sheet into top osb only? Seems not a good enough fix for the sheet.

[Mr Punter]

You could use the insulated metal sandwich panels.  I have some on a garage and there is no condensation.