I'm trying to find the pros and cons of various eco alternatives to expanding foam, for a deep external wall gap between stabilised-previously-crumbling Victorian brick and stabilised-previously-rotten wooden window frame.

Plan A would include using conventional gloss paint (from a recycling scheme) on top, but I imagine that might also have to be reconsidered?

Elsewhere on the forum i've seen burnt sand mastic recommended, but it doesn't look like it's enough on its own to fill a deep hole. Does anyone have experience of Auro 396 natural cork filler? Or are there others out there that would do?

Thanks, cath

Oakum caulking to fill the deep gaps, same as used for old wooden boats, finished with burnt sand mastic or similar over the top.