There's something on the roof....

[Feltwell]

Personally, I'd completely ignore a modicum of moss. A bit of moss on a roof seems normal to me, and helps it look "weathered in". A big lump of moss in a roof valley though, as shown on Malcom's picture above, I'd clear out.

Kreyszig's ferns, I'd be up there with some weedkiller. I made the mistake here of cutting a birch tree that was trying to grow out of my chimney back, thinking that would be it - damn thing refused to die and regrew. Next time I went up the (very, very tall) chimney, I was armed with a squirty bottle of Roundup weedkiller, it got the message and died and the remains then rotted away within a year.

 

[88v8]

what's the consensus on a bit of green stuff growing in chimneys?

Well, those ferns look rather splendid don't they, growing in the lime mortar, and that's some excellent brickwork you have there, but I wouldn't be happy if it were my chimney, the roots will accelerate the deterioration of the pointing.

However, some years ago at our previous house, I planted this in the roof 'cos I read somewhere it was supposed to be lucky. Just a sliver of soil inserted between the tiles. It grew happily on the east slope, as you can see it's flowering. Still there and not much larger when we left.

Ivor

 

[88v8]

Moss... I love the look of it, but it's a pain on thatch as there's no way to remove it without damaging the straw.
I'm going to try squirting it with Jeyes fluid, and I imagine with a long lance that would also deal with moss on a tiled roof.

Ivor

 

[Penners]

I planted this in the roof 'cos I read somewhere it was supposed to be lucky

I'm not sure it's going to be lucky for your roof. The plant isn't called sempervivum for nothing - it will live forever, growing and growing, and the tile that is currently slightly elevated will get pushed ever further upwards.

 

[a twig]

Have a really good old burn, get the chimney stacks glowing, that'll sort the issue!