Dome companies that use rigid insulation, cutting it to fit within the triangles, may have a serious condensation problem because the insulation board does not fit tight to the outside panel. This leaves a perfect space for vapor to condense on the outside panel. The only kind of insulation not subject to this problem is sprayed in place urethane. This material, when properly applied to dry wood, does not allow vapor to penetrate. However, there are other problem details to be dealt with correctly.
Urethane is also much more expensive than fiberglass.
Talk to us, after 25 years of building them, we know domes. Our ultra-insulated dome system works in cold climates as well as hot climates. Building a warm dome doesn't just mean more insulation. Our warm dome is economical to build. We don't want you sitting in your warm dome worrying about how you are going to pay the mortgage.