The Fire Resistant System
Fire resistance is the property of the material by which it can prevent or retard the passage of excessive heat, hot gasses, or flames under the conditions of use. For this system to work, there is a fire-resistance rating board which regulates and decides on the duration for which the passive fire protection system can withstand a standard fire resistance test, which has three distinct rating system the Class 125 Rating, the Class 150 Rating and Class 300 Rating. There are also various curves that are considered by most of the countries to establish the relation, like the building element curve used for residential and commercial spaces that are working by burning wood. For industrial facilities in the hydrocarbon & petrochemical industries, a hydrocarbon curve is used which reflects more rapid temperature rise.
Designing a fire building is to construct the structure including the floors, walls, beams, columns and the entire building envelope with materials that are non-combustible having the fire-resistant rating more than it is abided by the law and should necessarily sustain for atleast the time period required for the occupants to evacuate.
Achieving the objective
In order to primarily achieve a fire-resistant structure, there are certain design considerations that are to be taken, like the choice of the material should very obviously be fireproof also the main load-bearing walls should have a broader section so that they can act as barriers for a longer time. However, the results can be achieved by various different construction technologies like fireproof construction, noncombustible construction, wood construction and exterior protected construction.
The fireproof construction involved the construction of structures that has an inbuilt capability of being resistant to fire and also prevent the spread of fire which are only constructed using the fireproof materials having a minimum resistance power ranging from three to four hours such as steel, terracotta, concrete and so on. These buildings can be of 15 meters or above in height and can be offices, shopping malls, residential units or any other such space.
The noncombustible construction technology, however, restricts the usage of the fireproof materials just to the roofs and floors while the exterior facade is made up of brick or concrete, the height of the building can be above 15 meters and might be used for official purposes. The fire resistivity usually lasts from two to three hours.
In wooden constructions, the walls, floors and roofs even all of the structural materials are made up of wood wholly or partially. The resistance is withstood usually upto an hour, although the exterior bearing wall can extend it by an hour.
Lastly in exterior protected construction which is a technique adopted by most of the buildings wherein all the structural elements of the external façade is made of the noncombustible materials, this can be implemented in small dwellings, mixed occupancy or other such small shops. All other materials shall have an overall resistance of atleast an hour and all external load-bearing structures made up of noncombustible materials have an reacting resistance of more than an hour.
The appropriate materials
The choice of right material having the correct resistance rating is the most important step towards building a fire-resistant structure, some of these materials being glass, concrete, stucco, gypsum and so on. For ensuring complete safety one might install fire-resistant dual paneled windows which would double the time of resistance hence ensuring more time for the occupants to leave. Concrete being a noncombustible material takes longer time to burn or affect its structural load capacity because of its lower conductibility property which makes it more resistant than steel, therefore, it is an ideal choice for roofs. Stucco is a material that is typically used for wall and ceiling decorations which serve as an exceptionally good material for fire resistance. Gypsum, on the other hand, has an inbuilt noncombustible core that contains chemically combined water thereby increasing the fire-resistance rating.
Fire in a building can often be fetal and be responsible for large number of casualties hence having a building that ensures the absolute minimum time required for the occupants to evacuate the premises is an absolute need of the hour. There are several factors like the climate, availability of materials, budget and many more on which the structure depends also adding up on to the sustainable approach.