I am happy to see them recovering from it and wanted to share a couple of thoughts:
Fires during construction are, unfortunately, not uncommon, specially in historic buildings and can be very costly. Think Notre Damme, the Cutty shark, Windsor castle or the Glasgow School of Architecture, for example. This is why it is important that you work with the local fire brigades to plan accordingly.
In London, the LFB has a lot of useful advice (and can offer training) /safety/property-management/fire-safety-in-heritage-and-historical-buildings/
Also, be mindful and get an appropriate insurance if you are planning works