Shafts come in all sizes. A shaft can have skylight or open top, even plwood ow ebbing to keep birds out. I know that fires can spread rapidly once they get into the shaft. Roofs are opened to prevent mushrooming. There are two common types to shafts enclosed and open, enclosed is surrounded by building on all sides and open which is partially surrounded.
Shafts come in all sizes.
A shaft can have skylight or open top, even plwood ow ebbing to keep birds out. I know that fires can spread rapidly once they get into the shaft. Roofs are opened to prevent mushrooming.