Smokeproof enclosure
In building safety and construction, a smokeproof enclosure is a type of exit stairwell that has been designed to keep out smoke (and other combustion products) in the event of a fire, so that building occupants may more safely exit the building. == Description == Rather than entering the stairwell directly from the building interior, one enters a smokeproof enclosure by means of an open-air balcony or alternatively, a so-called open vestibule, and proceeds thence, to the stairwell itself.