I'm looking for some ideas on how to retrofit a firewall in some duplex residential buildings. They are rental properties, and the landlord is interested in taking advantage of utility incentives for envelope and HVAC upgrades. However, to qualify for incentives there must be a firewall from the foundation to the roof deck. These single story buildings have wide open attics and wide open crawlspaces. So, the trick is to come up with a method that could provide a 1 hour rated assembly that could be done in manner that is both practical and not excessively expensive. The incentives from the utility are good enough to make this step a consideration.
It appears that creating a separation between the attics would involve a double layer of drywall - tapped and mudded. That assumes there is enough of an opening into the attic to get drywall into the space. The job would be a pain, but I think its fesible.
For the crawlspace, adding a footing in the middle and concrete block would be quite intensive. However, the thought that is being proposed is installing a vertical "wall" to separate the crawlspace of each unit in the duples with foam board with some sort of structural support. I'm not sure that we can get a 1-hour assembly in this method.
Any one have any experience with this situation? Is it worth the trouble?