In July, a series of 3 large scale experiments were conducted that examined exterior fire spread into the eaves and how and the speed at which exterior fires transitioned to attic fires. The fires were ignited with a 100 kW burner simulating a small fire on the outside of a house. The fire was allowed to grow until the attic space was fully involved in fire and then was suppressed from the exterior side of the structure.
The three structures were constructed from exterior to interior with the layers described below:
Experiment 1 – Vinyl Siding, Weather Barrier, OSB Sheathing, Fiberglass Insulation, Drywall Interior finish
Experiment 2 – Vinyl Siding, Weather Barrier, Polystyrene Sheathing w/ Metal Bracing, Fiberglass Insulation, Drywall Interior finish
Experiment 3 – Vinyl Siding, Weather Barrier, Polystyrene Sheathing w/ Metal Bracing, Spray Foam Insulation, Drywall Interior finish (The attic was part of the conditioned space so the eave did not allow air flow into the attic space)
This video shows a side by side by side comparison of the three experiments.