With the roof and three out of the four walls on, and at least two days of rain forecast for the weekend, we had to act fast and get some plastic sheeting on, to protect the OSB3 outer skin.
The roof will eventually be clad in roofing felt (either charcoal mineral felt, or maybe strips of shingles - it depends on whether I can secure the shingles well enough to stop any driving wind from lifting them, as the roof pitch is only about 14 degrees).
But before any outer cladding goes on, we're covering the OSB3 with DPM plastic, just to protect the wood, should any of the cladding come loose at any time in the future (plus, it buys me an extra couple of days to get just the right sort of stuff delivered).
Under most of the beams secured to the floor, and at the bottom of every piece of OSB that comes into contact with any concrete structure (or anything that could possibly even potentially be a source of damp rising from the floor) we put strips of plastic. This plastic will be folded up and stapled to the walls, then an outer layer of plastic, from under the eaves to the bottom of the boards (covering the blue stuff) will be stapled on.
The roof took longer than expected to cover - making sure the plastic lay flat with no wrinkles or folds was a long, slow job; smoothing it out and stapling every half a metre or so. But the roof is now entirely water-tight.
Just got to make sure the walls are too.
Then when the (uPVC) cladding arrives, we'll be able to actually see it as a proper structure, not just large wooden box at the bottom of the garden!