New Roof and Tile Discolour

[newuser1]

Hi All,

I am after some more advice from someone expert. My extension involves a new roof and I have decided to get Marley Modern Duo in Brown but I notice couple of roofs which I believe have the same/similar tiles not sure whether its due to the color of the original tiles but after some time the roof is getting yellow like in the photo.



What could be causing this?

Many thanks for any help and advice

 

[dann09]

Occasionally, the colour leaches from concrete roof tiles - the "cause" could be a number of things; some connected with the tile batch/manufacture, and some connected with factors on the roof itself.
Then there's weathering from wind/rain and compass position.

For a heads up, send Marley tech dept. your above post and pic.

 

[^woody^]

That yellow is lichen growing on the tiles.

Its a phenomenon which may or may not affect certain tiles in certain locations.

It is not a defect and you wont prevent it

 

[newuser1]

Just an update...

I spoke to Marley and they say it is most likely mortar not mixed correctly and over time its leaking down from the ridge and suggested 3 to 1 of Sand and Cement mix.

So don't know if that it the cause and mortar is not likely to be yellow like in the photo is it?

 

[Xenon]

What Woody said is the correct answer.

 

[Alastairreid]

http://www.google.co.uk/imgres?imgu...qeWUe6XHcHN0QXrqYDQAQ&ved=0CDYQ9QEwAQ&dur=769

 

[newuser1]

Thank you for the responses. Interesting but it seems only some roofs are affected with lichen not all. Can I take any preventative measures to reduce the lichen?

Googling brings up people recommending metals/lead flashing to prevent it happening, apparently chemicals washing off the lead kills the lichen? can this be true?