On Monday, 5 October 2020 13:15:33 UTC+1, Pamela wrote:

All very true and something to do in spring. Meanwhile the wall needs
sealing as rain water is entering and I'm not sure if I should get plain
bitumen paint, roofing bitumen paint or acrylic sealant paint.

This was my shortlist:

https://www.wilko.com/en-uk/ikopro-f...ator/p/0243442
https://www.screwfix.com/p/thompsons...oof-seal/46708
https://polarcoatings.co.uk/product/leakseal-500ml

FWIW I had a similar problem with a flat garage roof and just
used the cheapest bitumen goo I could find and put a reasonably
thick layer on. It definitely worked on cracks and small holes
but AIUI cracks and small holes indicate that a "proper job"
needs doing. It did, however, give me an extra 2 years of
leak-free garage action. But I'm glad that it was re-covered
properly so I don't have to play the rainstorm lottery anymore.