Wow, ye olde fowle coope. Now I'm going to have to plant some edelweiss round the guinea pig shelter and construct some snow-capped mountains in the background.
One thing I didn't mention was that I didn't have enough tongue and groove or a suitable sheet of play to make the roof section, but I did happen to have a complete sheet of waterproof plasterboard left over from an en-suite shower project...
So, the roof will
never rot, but weighs about half a tonne and could survive a nuclear strike.
I do like employing off the wall engineering solutions - in this case, off the shower wall.