Decking - What causes this?

[imamartian]

I'll keep an eye on it over the winter.

Does anyone know if the bleach will effect the oil in anyway? Will I need to re oil after using bleach?

Decking timber is very resilient, a bleach wash won't harm it.... and you want to be oiling it every year or two, but winters aren't really a time for worrying about it... have a check every spring, see how it looks...

more importantly, i'd have a quick look around the handrails especially if you've used metal brackets and steel screws? rust is a much bigger irritant !!

 

[terryhawkins]

If it starts to get really bad over the next month or so then I would like to think about giving it a bleach wash asap.

Obviously oiling the deck at this time of year isn't going to happen, so I'd like to know if the bleach will remove the oil or affect it in any way?