[throwmeawayl8r]

It seems like the weight of amount of water/retardant to effectively extinguish a fully-involved fire would be a problem AND simultaneously smothering the fire underneath AND reducing core coal temperatures below ignition point would need to happen. It's a thought towards a possible solution to a ruinous class of fires, but there appears to be a need for a gentle and widely-deployed technology to rescue historic structures in the midst of fire events.

1. Cool an outer structure rapidly with lightweight/gently-applied, inert, high specific heat material from above.

2. Thixotropic gently-applied, inert, high specific heat material inner structure (possibly same as 1.).