My Colorbond roof appears to have mould on it which has been there since I purchased the property. I’m wondering if there’s a way to clean it off? I have a pressure cleaner from Bunnings but unsure if that’s enough. Thanks!
I'd suggest a bit of a combination between 30 Seconds 5L Roof Treatment Concentrate and possibly your pressure sprayer. You can either spray the product and leave it for up to 6 months before the lichen fully decays and washes off in the rain or spray as much as you can off now with your pressure sprayer before applying the product.
It's best to get the 30 seconds product on there as soon as possible and let it do its work. I'd recommend doing the work from a ladder if possible, as it would be pretty dangerous to get onto the slippery Colorbond roof whilst it's wet. Your pressure sprayer won't do much to the lichen unless you can get the nozzle up close to it. If that requires you to get on the roof, I would advise you to leave it to the professionals.
Unfortunately, you might find that the lichen has secreted destructive acids causing damage to roof materials. This might appear as a discolouration even after the lichen is removed.