There is a product that will work on leaky anything. It’s a rubber spray that cures by absorbing dampness from the atmosphere. In dry conditions the spray heads also release a water mist to aid curing.
It’s used for pond liners and flat roofs and was developed in Canada I think.
Can’t for the life of me remember it’s name but if you can find a pond lining company and drop off the roof they would spray the inside for you with a 3mm coating. It has something like a 300% stretch rate anorl.
Ain’t nothing coming through that.
