Rainscreen performance during wildfires
I have started to work with some of the homeowners who were affected by the recent Colorado wild fires. To that end, I am putting together a presentation to begin to explain to local homeowners how to rebuild in order to best resist future fires. The presentation will highlight how many sustainable construction techniques for improved energy performance and durability also have benefits for wild fire resistance.
One strategy that I have not yet resolved is whether or not a rainscreen would be beneficial or detrimental (or neutral) to the overall system from the standpoint of fire resistance. The system that we are considering would be a cement board rainscreen over continuous mineral fiber board insulation over structure (preferably CMU though it will most likely be 2x stud). Is there any danger with regard to a chimney effect being created in the air space between the rainscreen and insulation? It seems that special concern would need to be paid to the furring strips; wood is clearly a no-no, steel seems to be preferable since it is non-combustable though I have some concerns about the steel losing strength under extreme heat (special attention would have to be paid to fasteners as well). Would the rainscreen provide any benefits by creating a buffer between itself and the insulation?
Has anyone come across any information on this? Tests, data or precedence? There is another thread on GBA that started to discuss the issue:
though it provides little specific information and quickly (d)evolves into a discussion on moisture issues.
Any information or thoughts would be appreciated.