Vertical separation of windows using spandrel walls and horizontal projections

Actual fires and full-scale tests demonstrate the hazard of the leap frog spread of fire from a window to the one above. A spandrel wall or a horizontal projection (such as a canopy or a balcony), installed above an exposing window, protects storeys above from flames issuing from the opening. The described tests show that a horizontal projection is very effective; however, for a spandrel wall to be equally effective, an impractical height of spandrel is required.