Geodesic Dome

[MarkP]

I was once considering trying to make a living space out of a steel arch structure. I saw utube videos of people doing just that. They sprayed foam on the inside of the steel arch. I started searching about the use and hazard of such foam. Apparently there are a fair number of large steel arch storage structures in the midwest used for storing large quantities of potatos, insulated with spray foam on the inside. Generally speaking not much bad has happened, but in one instance, when welding was being done, a fire started. While you can hold a chunk of foam in a flame and the foam won't continue to burn when withdrawn, that's just a small piece. Apparently it is a whole different story when the foam is on the inside of the structure. In this case the foam started to burn, slowly, a couple of times in the immediate vicinity of the welding and it was easily extinguished. This perhaps led to a certain degree of complacency on the part of those involved. The last time the fire got away from them. This was a large open agricultural structure without, as far as I know, any individual rooms. All that was necessary was for people to look up, see the fire, and run, which they did. The last ones almost didn't make it because the fire spread so fast. The fire was inside a tube of insulation (the interior of the insulated steel arch) and there was no where for the heat to go. Huge difference between that ans a small exposed chunk of insulation. Whodathunkit but the difference in flame spread was incredible. Reminds me of when a decade or two ago I helped set off the fireworks from Flat Island in Kailua Bay. As part of the pre-event orientation the professionals showed us volunteers how much difference it made to have the craft paper covering on the green gunpowder-impregnated wick material. They rolled out 10 feet and removed the craft paper from the first foot. They lit the bare end. It took something like 30 seconds for the bare section to burn one foot. The remaining 9 feet that had the covering burned in something like 1/4 of a second.

So, I am not sure how safe exposed foam on the interior of a dome would be.