It's a terrace shed that has roof made of tin-can steel.
There are no trees or buildings higher than this.
I wonder how rain has brought this much dirt onto the top of my roof.
Should I clean this or this dirt is nothing to get bothered about ?
It's a terrace shed that has roof made of tin-can steel.
There are no trees or buildings higher than this.
I wonder how rain has brought this much dirt onto the top of my roof.
Should I clean this or this dirt is nothing to get bothered about ?
You'd be amazed how far sand can travel in the air.
I've on occasion seen my car looking like that after a particular wind/rain pattern. I'm in the UK, the sand came from the Sahara, well over 2,000 miles away.
Explainer: how does Saharan sand end up in the UK?
As to what to do about it - the next rain storm will probably wash it all off again. Unless you're particularly worried about the cosmetic appearance, leave it to the weather.
Splash from the ground. Pollen. Dust. Yes. (Where else do you think it came from? If someone was throwing sand on your roof, hopefully you'd notice...)