Engr. Osaz’ ENOBAKHARE is an award-winning Contractor, Structural Engineer and the CEO of Heavens Contractors Ltd. He is involved in design and construction of buildings, roads and infrastructure projects across Nigeria. Email: engineerosaz@gmail.com Phone: 08167394799


Emergency exit in buildings is essentially designed for quick escape from hazards like fire and other forms of attack. When there are exigencies of such nature, the use of escape routes comes to bear. The positioning and allowance of escape media should be such that nothing is taken for granted. It is not uncommon to see spiral stairs of metal, concrete or composite type installed in position of emergency exits in buildings across the country but research and common sense show that this form of exit is not very effective in times of emergency.

The use of spiral stairs as exit media is not exactly a bad idea but its use as an emergency exit especially in assembly buildings like worship centres and halls or other building types with high occupancy ratio like hotels, multi-storey residential/commercial buildings or condominiums is where the problem lies. The rush of crowd from an emergency situation can be further hampered by attempts by individuals to make sharp angular turns at close distances between steps on a spiral stairs. The intense pressure and panic associated with an attempt to escape coupled with the range, size or rate of spread of the attack might cause intending escapees to get stuck at the exit area. It is a fact that the use of spiral staircase as emergency exit poses another form of danger to those who must have assuredly relied on it as an escape route hence some states in Nigeria (e.g. Lagos) have frowned at it.

Consider this simple scenario – a couple of people trying to escape an electric fire attack from an upper floor say a regular 3-floor height, each person may have to make at least 9 sharp turn joggling down from riser to riser before they can alight at the ground floor. The issue then is with each person trying to outrun the other within a small stair-width and considering the angle of turn and the steepness of typical spiral stairs, there is a higher tendency for the occurrence of multiple somersaults which may cause serious injuries and even instant death. Sometimes because of the height and mode of fall and perhaps the degree of injury sustained during the fall, such victims of summersault or associated stampede may have to contend with a duo challenge on their hands that is getting enough strength to get up from their landing position and then the original burden of completing their escape episode. This action could be dramatically horrible and have accounted for quantum loss of lives in past and recent building fire-outbreak scenarios. This is not to say that such cases of falling off are only peculiar to spiral staircases –No! Fear, panic and ‘adrenalin action’ can make people escaping from an attack via a straight-flight staircase fall-off like ‘they don’t care’ but it is very likely that if the same number of unsuspecting victims, under the same condition of attack use a spiral staircase as emergency, there would be higher casualty.

Although most building owners especially those mindful of what is often described as ‘maximal use of space for increased value’ are reluctant to allow greater space for the installation of decent emergency exit(s) and would rather prefer any staircase that can squeeze itself into a small area, the use of spiral stairs especially the typical metal variant is not ideal and no longer in vogue. But for developers or building owners with this sort of mindset and where building regulations do not restrict, there is a way out and that is the use of helical stairs. Helical stairs are different from spiral staircases in elevation and take up spaces slightly larger than that of their counterpart.

It has been observed that where new building regulations forbid the use of typical spiral staircases as emergency exit, some developers have added more spaces to accommodate the replacement of their spiral staircases with helical stairs. These stairs also allows for turnings but such turns are not as sharp as those of typical spiral stairs and are generally safer. Half-turn and straight-flight stairs are amongst the best options for emergency exits. It is therefore advisable that at a time when building fire incidences have become prevalent, developers and building owners especially of assembly and high density buildings begin to think aloud and do the needful.

Source: http://independentnig.com/2016/07/19/why-you-should-avoid-spiral-staircase-as-emergency-exit-2/

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