Black Mould Adjacent to Window in Sun Room Conservatory

[Oldlandite]

We have a sun room/conservatory. Where full length window abuts single brick thickness wall there is a strip of black mould approx 6 ins wide the full height of the wall. Wall is rendered on outside. It is upvc window frame. There is also a radiator attached to wall close to window. Mould can be readily washed off but recurs. Is there a mould resistant paint we can use or other action we can take without putting up a layer of insulation blocks outside and re render.

[DIYDoctor1]

Hi Oldlandite,
Here is an article with everything that you need to know about stopping black mould: https://www.diydoctor.org.uk/projects/damp-and-mould.htm

There are also some recommendations for projects and techniques to stop the mould returning.