sdash

Very sorry to hear of your loss. I have taught at the jr. high, sr high and university level since the early 1970's and twice experienced fire in one of my shops. Both were related to a spark or heat generated from use of a table saw. In both cases a dust collection system was involved and the fire was not discovered for an extended period (4 - 12 hours) after the shop was shut down. Good smoke detection that reported to a central monitor point kept damage to a localized area and minimized damage. With today's technology (not residential style detectors) it is possible to install a system that would report to your house or even to the local FD. As a suggestion, when you rebuild. consider ICF with rated plywood sheeting on the walls. Based on my experience the well-insulated concrete structure makes a great shop.