This is my second spring in this bungalow. Last winter we noted
interstitial condensation in the (boarded) attic and it was suggested
putting in roof vents would help so we did.

This year there are items in the attic, an office chair in particular,
which has mould on it.

The gable ends of the bungalow are approx North & South, so one roof
is facing East and has some but not a lot of moss, and the other roof
faces West with quite a lot of moss. I'm in the process of cleaning
it off - concrete tiles and I estimate 1000 of them.

We're fairly high up, 120m above sea level but the housing development
is in a bit of a dip, about 15m and we're against the North face of
that dip.

So two issues -
Mould - why? How to cure?
Moss - why? How to clean/stop?

Are the two related?

--
AnthonyL