Slate re-roof - Replaced slate is orange/brown - advice needed

By the sounds of it they are using a reclaimed Spanish which are a lot cheaper than Welsh 2and hand and the brown you see is the iron washing out the slates I'd definitely pick them up about it before the job has finished

Hi. Unfortunately it is a permanent stain which is caused by a numerous amount of metals that are naturally in slate such as iron, aluminium oxide, magnesium oxide and titanium which will cause brown/orange/white streak marks on the slate and can sometimes run on to the slate below or even stain any lead that maybe below it such as lead flat roof or flashing etc. If it is "bugging" you then maybe worth getting them changed but it will not cause any damage such as leaks. Hope this has helped. 👍

I believe but don’t quote me here as it’s hard to know without seeing but it is rare phenomenon that sometimes happens the issue has got a name I’ve heard it before but I can’t recall it, if they are brand new slates they should come with a manufacturers guarantee for exactly this issue. I’d let the company who are in charge know your not happy, so they can get onto the suppliers and they can come out and see if what they can do I imagine there just give you new slates. I don’t think it’s necessary anybody fault either, unless the company in charge knew they were buying really cheap slates that aren’t to BS EN12326 classification. Sorry to hear of your troubles and hope you get this sorted, Regards Frankie

Welsh slates do not contain any contamination from other materials, cheap slates have a metal called pyrites that will rust causing discoloration

With been a natural slate there Will be imperfections this is something you should discuss with the roofers who are carrying out the work