In keeping with city fire codes, the building had a brick exterior to prevent fires from spreading from building to building as in the Great Chicago Fire of 1871. However, its interior was made almost entirely of combustible wooden materials—stairs, walls, floors, doors, roof, and cellulose fiber ceiling tiles. Moreover, the floors had been coated many times with both flammable varnish and petroleum-based waxes. There were only two (unmarked) fire alarm switches in the entire school, and they were both in the south wing. There were four fire extinguishers in the north wing, each mounted off the floor, out of reach for many adults and all of the children.