26th May 2015
I thought it would take me a day to put the greenhouse roof on. In the event, it took Ford and me nearly three days. As usual, I hopelessly underestimated the complexity of the task, perhaps because this roof seems so simple compared to the all-singing, all-dancing super-insulated main roof. It's just some glazing bars and sheets of polycarbonate screwed down onto the rafters of the oak frame. Nonetheless it presented a few problems (for us novices) that needed thinking through and a little experimentation to resolve.
The unheated first-floor greenhouse is outside the insulated envelope of the building, so we don't have to worry about air-tightness and energy losses here. Unlike the main part of the house, it is going to be properly draughty. But that doesn't mean it's okay for the rain to come in. The difficulty in building any roof, however simple, is ensuring that every junction and turn is finished in such a way to keep the rain heading in the right direction. Which ain't so easy when you have overlapping rubber gaskets and connecting glazing bars.
As you can see in the photo above, when it was all done, Ford levitated just under the roof while I opened a hose over it. He stayed dry while the water poured off the edges. All we need now is a gutter to direct the water on to the bathroom roof, from where it will eventually drain into a rainwater tank in the greenhouse. I'll fix that gutter tomorrow - it should only take me a couple of hours.