Discolouration on roof tiles . .what is it?

[TheSalad]

Hi All - any clue as to why we see some green discolouration down the line of our flue (the chimney is a false one). No other house in the block of six has it only ours. Any ideas? View media item 21289 View media item 21290

 

[ColJack]

it's algea ( sp? )
same thing that makes slabs go green..
might just be that it's in the shade at that spot most of the day so it's not drying out as fast as the rest of the roof.. or you've got condensation dripping out of the flue all the time..

 

[Nige F]

Have they got an ariel pole like yours on their chimney - are they really false chimneys . that pole is in line with the stain OR -if that ridge tile vent comes fom your bathroom - do you eat a lot of curry

 

[regsmyth]

Could it be from bird poo? Do they roost on your aerial?

 

[Johnmelad502]

Coljack is wrong, your problem is algae.

 

[roughcaster]

Could it be from bird poo? Do they roost on your aerial?

I'd put money on that being the cause.

 

[wotan]

Nice gaff

 

[TheSalad]

Thanks all for your comments. My initial thought and concern was that it was algae caused by condensation from the flue. But I like the bird poo idea. Will keep a close eye out for roosting sh*%ing pigeons.

Thanks again.

 

[roughcaster]

Have a look around at other roofs where the TV aeriel hangs out from the chimney,,, you'll find a lot of them are discoloured, or have algae growing due to the bird ****e.
There's ****e on the roof, and ****e on the telly,,,, blame the aeriel.