Posted: 03/11/2013 at 10:22
I wouldn't accept mouldy woven panels, but I think timber posts with a bit of black slime/mould on them are acceptable. You'd pay a lot more for posts that had been stored under cover, and if they've been pressure treated they'll be fine - the mould will be on the surface only.
As Fg says, contact the supplier if you're not sure about it.
I would also ask the builder for a copy of the invoice for the timber, as this should carry the statement that the wood has been pressure treated - therefore if it rots too quickly you'll have some come-back.
Edited to say: I suppose I should add that I'm from a farming family and an ex smallholder - also my ex was a builder, and quite a good one even if he is my ex. He'd have been happy to use posts with black slimy mould on them as long as they'd been pressure treated. He used a small supplier who didn't have undercover storage for everything, and therefore was able to charge less for his timber. Never known any complaints.