It appears from the published images of this fire the building, the F1 warehouse, seems to be constructed of block with zinc roofing. What it did have was flammable contents. The layout (Google Maps) of the Merca shows about seven long warehouse type structures with service roads separating them and other smaller satellite buildings The service roads act as fire breaks. The design was wise, it prevented the Merca fire from spreading. Imagine the loss if the facility was all under one roof. Fortunately, there were no injuries or loss of life reported as a result of the fire.