Waterproofing the roof
Terra Dome house being built in Maine
We're getting closer, looks like we may move in the end of next month. We're still working out details on the waterproofing. The roof has a couple of layers of black rubbery stuff (spray on), then bentonite sheeting (Paraseal) in key locations, along cold joints. Above that drain pipe was laid in all valleys between modules.
Above all that, some dirt (sandy Maine soil) was put on top to even out the topography, then insulation board, then more dirt on top.
We just had a big rain, and have some leaks. It looks like the insulation board is forcing the water to flow to the edges of the roof. Currently you cannot walk anywhere near the edge--you'd sink. The water seems to be being held by the insulation, so it can't get to the drain system (well, it is probably trickling through). The plan is to put perimeter roof drains *above* the insulation.
I'll let you know how it works, next time it rains. That might be April if the cold shows up.
Steve