OSB

Very droll, however: Only use OSB3 for outside such as hoardings. OSB1 & 2 are not sufficiently moisture resistant. :)

AWEM

I would tend to agree but years ago I was putting down some rough concrete for a shed base and had not got any suitable ply for shuttering and used bog standard OSB offcuts. Once the concrete had gone off I would usually remove the ply but for some reason I did not do this and later thought " oh the osb will turn into weetabix in a couple of months and I can just rake it out" How wrong I was, some of it is still in place and whilst looking a bit worse for wear and swollen, it will still take some effort to get it out.

So for hoardings up for a few months, I'd expect OSB1/2 to be adequate even if not in spec.

Bob

Quite a few of the 'sheds' actually sell only OSB3 so maybe your WAS osb3 !

AWEM