Building Code Of Australia (BCA): A Comprehensive Guide

The Deemed to Satisfy Provisions for Fire Safety Regulations

1: Discuss  the  statement  “In  Australia,  all  buildings  must  comply  with  the  deemed  to  satisfy  (DTS)  provisions  in  the  Building  Code  of  Australia”.  Illustrate  your  answerby referring to the Hierarchy of Requirements.

2. Classify  the  following  building according  the  BCA  and  give  the  reasons  for your answer 

                                              

                                                             Figure 1 Royal Crescent, Bath, England.

The  complex  has  many  dwellings,  that  share  common walls  with  a  fire  resistance  level  of  90/90/90. The dividing wall extends above the combustible roof. 

3: Determine  the  ‘rise  in  storeys’  for  the  following  building in  Figure  2 and  give  the reasons for your answer

                                

                                                                  Figure 2 Section through a residential complexQuestion

4: The external walls of a building are required to be fire-resisting when they areexposed and close to a side or rear

boundary.Contrast  the  two  different  methods  used  to  determine  if  a  wall  in a  Class  1 and Class  2  building is exposed to a fire source feature 

5: Determine  the  Type  of  Fire  Resisting  Constructionrequired  for  the  following  building and give the reasons for your answer.

                        

                                                                 Figure 3   Section through a Factory/Office complex

6. Determine the fire resisting requirements for the external walls of the Class 2 building  shown  in  the  following  site  plan  (Figure  4)  and  give  the  reasons for  your  answer. 

The Class 2 building has a Rise in Stories of 2

                                                         

                                                              Figure 4 Site Plan of Class 2 building and Garage

7. Determine whether the exits serving the sprinkler-protected office in Figure 5 are required to be fire isolated and provide the reasons for your answer.

                                           

                                                               Figure 5  Section through Office building

8. The building shown in Figure 5 has typical floor area of 1250 m2. Calculate the aggregate exit widthrequired assuming that the two exits shown in the diagram are required to satisfy the travel distance requirements, give the reasons for your answer and provide all of your workings and assumptions 

9. Determine  whether  the  egress  from  the  single  storey  building  in  Figure  6  complies  with  the  BCA  ‘travel  distance’  requirements  and  provide  the  reasons  for  your  answer. Each shop is a separate sole occupancy unit.

                                        

                                                                     Figure 6 Site plan of Shopping complex

10. Determine the emergency lightingand exit sign requirements for the building shown in Figure 6 and provide the reasons for your answer. 

11. The single storey factory building in Figure 7 comprises three (3) sole occupancy units, each being a separate fire compartment with a floor area of 400 m². Determine the fire hydrant and fire hose reel requirements for the building and provide the reasons for your answer.

                                                     

                                                                       Figure 7 Site plan of Factory complex

12. Outline which types of buildings must have sprinkler protection. Explain the rationalefor sprinkler protection in these buildings

1. This statement means that every building in Australia must have certain components and design elements/factors and be constructed using high quality materials and by following specific procedures so as to meet particular functional and performance requirements of the Building Code of Australia (BCA), particularly fire safety requirements. For example, ceiling heights of habitable rooms in a building must not be less than 2.4m and buildings must be constructed using materials that resist fire for a certain period of time depending on the class of the building. All these are aimed at ensuring that the building has near-zero risk to the occupants and neighboring buildings or other property. When a building is constructed by strictly observing the deemed to satisfy (DTS) provisions, it will automatically meet or comply with the fire safety regulations (Gardner, 2016). The DTS provisions are basically technical specifications that are designed to ensure a building has the capacity to adequately resist fire over the expected period.

The hierarchy of requirements for buildings in Australia has four levels (Wilson, 2015). Level 1 is the objectives which is basically the expectations of the community for the buildings (i.e. reasons to ensure that buildings safeguard occupants and adjacent property). Level 2 is functional statements which is by what means the building can meet the objectives stated in Level 1. Level 3 is about the performance requirements which outlines the desired level of performance that the design factors, materials and construction approaches of the buildings must meet. This ensures that the building constructed meets the required functional statements. Level four is the building solutions which highlights the means on how the building should comply with the performance requirements. Level 4 has two other sub-levels: level 4a – DTS provisions and level 4b – alternative solutions. DTS provisions are basically a list of design factors, building components, materials and construction methods that will enable attainment of BCA’s performance requirements if used. Alternative solutions entail innovative or other materials and construction approaches that can be used to conform to the performance requirements of BCA (Ellison, 2018).

2. The classification of the building provided in Figure 1 in the question paper is Class 1a. This is because the complex has several attached dwellings with each dwelling being a building (Australian Building Codes Board, 2016). Another reason is that the attached dwellings are separated by a common fire-resisting wall. This is building classification is in accordance with Section A, Part A3 of National Construction Codes (NCC) Volume One (Australian Building Codes Board, 2015).    

3. The rise in storeys (RIS) is the sum of the highest number of floors or storeys, including those at the building’s external walls and within the roof space. Since the ceiling height is not more than 1 m above the finished ground level’s lowest 12 m section and the ground floor or basement is exclusively for vehicles’ accommodation (car park), the basement is not considered in calculation of RIS. The method of calculating RIS is provided in clause C1.2 of the BCA Volume 1. The rise in storeys is used to estimate the fire risk of a building.

The Hierarchy of Requirements for Buildings in Australia

The building in Figure 2 is class 2 because it comprises of several sole occupancy dwellings with each dwelling being a separate unit. The total storeys of the building are three but the ground floor is only for accommodating cars hence not counted in RIS (Victorian Building Authority, 2018). Therefore the RIS for the building is 2 (2 x Class 2 storeys).

4. The two methods used to determine if a wall in a Class 1 and Class 2 building is exposed to a fire source feature are as follows:

In the first method, a wall in a Class 1 and Class 2 building is exposed to a fire source feature if any horizontal straight line between the fire-source feature and the building is not obstructed by a wall that has a fire resistance level (FRL) of not less than 30/-/-.

In the second method, a wall in Class 1 and Class 2 building is exposed to a fire source feature if any horizontal straight line between the fire-source feature and the building is not obstructed by a wall that is neither translucent nor transparent. This is in accordance with Specification C1.1, Clause 2.1 of the BCA Volume One.

Therefore the first method is about determining the distance between the wall in question and the fire source feature, such as nearby road or other property. Generally, a wall that is closer to a fire source feature is more exposed to fire than the one at a greater distance. On the other hand, the second method is about the fire-resistance properties of the wall and the fire hazards or risk level of the fire source feature. For instance, a wall that is next to a storage facility for combustible materials is more exposed to fire than the one next to a hospital.

5. The type of fire resisting construction (usually referred to as type of construction) is determined under the guidance of Specification C1.1 of BCA Volume One. The type of construction depends on several factors, including class of the building, rise in storeys and volume or floor area of the building. The building provided in Figure 3 in the question paper is Class 8 (since the largest portion of the building is a factory). The mezzanine floor (office space) of the building has a floor area of 180 m², which is less than 200 m² or one-third of the total floor area of the building hence it is not recognized as a storey (according to Specification C1.2 (d)(i)). The building is Class 8 and has an internal height of 7 m (which is more than 6 m) thus it is considered to be one storey (according to Specification C1.2 (c)(i)). From Table C1.1 in BCA Volume One, the type of construction for the building is Type C (rise I storeys = 1 and class = 8). Type C buildings are those that are located over 3 m away from a fire source feature. None of the elements of building require to have a FRL as the fire risk is very low.

Building Classifications and the Rise in Storeys

6. The fire resisting requirements for the Class 2 building’s external walls are determined in accordance with Specification C1.1 of BCA Volume One. Since the building is of Class 2 and its Rise in Storey is 2, the type of construction is Type B (Table C1.1 of BCA Volume One) (Queensland Building and Construction Commission, 2014). Thus the fire resisting requirements for the external walls of this building, based on Table 4 of Specification C1.1 in BCA Volume One, include the following: the load bearing parts of the external walls that are from 1.5 m to less than 3 m must have a FRL of 90/60/30; the load bearing parts of the external walls that are from 3 m to less than 9 m must have a FRL of 90/30/30; the load bearing parts of the external walls that are from 9 m to less than 18 m must have a FRL of 90/30/-; the non-load bearing parts of the external walls that are from 1.5 m to less than 3 m must have a FRL of -/60/30; and non-load bearing parts of the external walls that are from 3 m or more do not require to have a FRL.

7. The exits serving the sprinkler-protected office in Figure 5 are required to be isolated because of several reasons. First, the building has more than three storeys hence its lift shafts and their exits should be separated (according to Specification C2.10 of BCA Volume One). Second, these are exits opening to fire-isolated stairways and not to open spaces or a road hence they need to be isolated. Third, the exits should be isolated so as to prevent penetration of other sides besides water supply pipes, electrical wires and pressurization system ducts. Other reasons for isolating the exits are: to maintain separation of fire partitions, to prevent exposure to fire source features, and to facilitate easy escape during evacuation in case of fire outbreak.

8. Aggregate exit width is based on the number of people in a mezzanine, room or storey/floor.

Number of People =

In this case, usable floor area = 1,250 m²

Number of m² per person = 10 m² (obtained from Table D1.13 in BCA Volume One).

Number of People =

This means that each floor of the office building provided in Figure 5 in the question paper can accommodate 125 persons.

As aforementioned, the size of exit width is determined by the number of people that will be passing through that exit during an emergency. Since the storey accommodates more than 100 persons but less than 200 persons, the aggregate exit width must not be less than 1 m plus 250 mm for every additional 25 persons (this is in accordance with Specification D1.6 (c)(i)). Thus the aggregate exit width is calculated as follows:

9. The building provided in Figure 6 in the question paper is a Class 6 building (shop). The egress from the single storey building in Figure 6 complies with the BCA “travel distance” requirements because the floor of the shops is 24 m long and 8 m wide. This means that there is no point on the floor that is more than 30 m from an exit (each sole-occupancy unit in the building has only one exit). This determination is in accordance with Specification D1.4 of BCA Volume One.

The emergency lighting requirements of the shopping complex in Figure 6 provided in the question paper include the following:

• An emergency lighting system that complies with AS 2293.1 has to be installed in every room or shop of the building because there are points on the floor of the storey that are over 20 m away from the nearest doorway leading to an open space (public roadway).
• An emergency lighting system that complies with AS 2293.1 has to be installed in every fire-isolated passageway or stairway in the building or in every shop.
• An emergency lighting system that complies with AS 2293.1 has to be installed in the storey of the building because it is a Class 6 building and the total floor area is more than 300 m².

The exit sign requirements of the shopping complex in Figure 6 provided in the question paper are as follows:

• A clearly visible exit sign that complies with AS 2293.1 has to be installed on, adjacent or above the door or exit of each shop. This is because the door provides direct access to the public roadway, making it easier for people to exit the storey for safety during an emergency.
• A clearly visible exit sign that complies with AS 2293.1 has to be installed on, adjacent or above any door or exit of the building that serves as the required exit of the building.

The above requirements are in accordance with Specification E4.2 and E4.5 of BCA Volume One.

The fire hydrant requirements of the building provided in Figure 7 in the question paper are as follows:

• The installation of the fire hydrant system must be in compliance with AS 2419.1 requirements.
• Only one internal fire hydrant should be provided to serve the building because it is in Class 8 and is single storey (not more than 2 storeys).

The fire hose reel requirements of the building provided in Figure 7 in the question paper are as follows:

• The fire hose reel must be installed to serve the entire building (if more than one internal fire hydrants has been installed) or any fire compartment (if no internal fire hydrants are installed).
• Installation of the fire hose reel system must be in accordance with AS 2441
• Only one fire hose system should be installed at the egress level of the building because it is a Class 8 building with 3 sole-occupancy units.
• The fire hose reel can be installed inside, outside or in combination of the two so as to achieve the requirements of AS 2441.
• Location of the fire hose reels must be within 4 m to the exit.  
• The fire hose reels should be installed such that they do not have to pass through doorways with smoke or fire detectors.
• If the water supply of the building is unreliable or does not meet the required flow and pressures of AS 2441, a water storage facility, pump or both must be installed so as to achieve the minimum flow and pressures.

The above requirements are in accordance with Specification E1.3 and E1.4 of BCA Volume One.

12. The buildings that must have sprinkler protection are:

• Class 3 residential buildings especially those used as residential aged care buildings. This is because occupants of these buildings are slow to respond to any emergencies and therefore they need to be safeguarded by sprinkler systems.
• Class 6 buildings because they are generally small, medium and large shops visited by all kinds of people, including children, youths, adults, elderly people and persons living with disabilities. Large number of people visit these buildings at a time thus the necessity to provide sprinkler protection.
• Class 7 buildings especially public car parks and wholesale or storage buildings. This is because the buildings are visited by all kinds of persons and are also used to keep valuable and useful products. In case of a fire event, a lot of lives and property may be destroyed or lost if the buildings do not have sprinkler protection(Londo, 2017).
• Class 9 health care buildings such as nursing homes, hospitals and clinics especially those used as residential aged care buildings. This is because majority of people living in these buildings are disadvantaged to respond to an emergency either because of their old age or deteriorated health conditions. As a result, it only makes sense to provide sprinkler protection in these buildings.

References

Australian Building Codes Board, 2015. National Construction Codes (NCC) Building Code of Australia Volume One, Canberra: Australian Government and States and Territories of Australia.

Australian Building Codes Board, 2016. National Construction Code Volume Two Building Code of Australia Class 1 and Class 10 Buildings, Canberra: Commonwealth of Australia and States Territories of Australia.

Ellison, M., 2018. What is the Performance-Based Building Code. [Online]
Available at: https://www.constructionlawmadeeasy.com/WhatistheperformancebasedBCABuildingCode
[Accessed 12 September 2018].

Gardner, P., 2016. Fire Engineering Report, Dandenong, Victoria: Exova Warringtonfire Aus Pty Ltd.

Londo, G., 2017. Why Fire Sprinkler Systems are Important. [Online]
Available at: https://www.frontierfireprotection.com/why-fire-sprinkler-systems-are-important/
[Accessed 12 September 2018].

Queensland Building and Construction Commission, 2014. Building Codes of Australia (BCA) Classes of buildings. [Online]
Available at: https://www.qbcc.qld.gov.au/building-codes-australia-bca-classes-buildings
[Accessed 12 September 2018].

Victorian Building Authority, 2018. Multi-Storey Residential Buildings - Warranty Insurance Exception, Melbourne: Victorian Building Economy.

Wilson, L., 2015. Building Code of Australia Performance Hierarchy. [Online]
Available at: https://universaldesignmeetstheexitsign.com/white-paper/performance-based-building-codes-2/building-code-of-australia-performance-hierarchy/
[Accessed 12 September 2018].