I am a Director of Development Certification Pty Ltd and have been a Building Surveyor since 1989. I have a bachelor degree in building surveying and I am a qualified carpenter. I have been in the construction industry since 1981. I have a real passion for the building certification profession as I believe building certifiers are the general practitioners of the construction industry. Our role is not only to know building law and apply it, our role includes assisting in the development of the knowledge of all in the industry by sharing our knowledge and experience.

What’s the difference between Class 1 and 2 Dwellings? Here are the basics.

Class 1a Dwelling Units
Class 1a Dwelling units have a separating wall between each dwelling unit that extends continuously from the ground to the underside of the roof of the units.

Class 1 buildings cannot be built on top of each other, and each is totally independent of the adjoining class 1a except they share a separating wall.

Please note I did not use the term fire wall. Separating walls function as fire separation, however, they are not fire walls as defined in the BCA Volume 1.

Class 2 Dwelling Units
Class 2 dwelling units are not independent of each other like Class 1a buildings. They can share entries, hallways and roof space, or be built on top of each other.

In a Class 2 Dwelling, the space contained within the floor, walls and ceiling of the dwelling unit, is separated from the other common parts of the building or other Class 2 Dwellings. The separation is achieved by constructing the bounding floor, walls, and ceilings of the dwelling to comply with the required fire, sound, impact and insulation ratings.

Please note I did not use the term fire walls or separating walls. Class 2 buildings do not use fire walls or separating walls to separate dwelling units.

You can read the technical definitions of these classifications here.

Applying the BCA

The ABC of the BCA

This phrase “ABC of the BCA” is a simple but memorable one that I made up years ago. As a building certifier it has become an incredibly useful tool and has helped me to do my job well, every day. It does not matter if you are just starting a design, if you are halfway through a design, if you are looking at a building under construction, or if you are inspecting a fully completed building. If you apply this simple “ABC of the BCA” rule, you will begin to easily establish what you need to know and where to find it.

Applying previous building legislation

Will tomorrow’s rules impact your design today?

Let’s look at another hypothetical situation: You’ve just completed the design of your development project. All costing has been finalised, the project has an agreed budget, and the landowner is happy and has signed off on the design.

But wait, building assessment provisions have suddenly changed. This means a major redesign of the development, an increase in the project’s budget, and most likely, an unhappy client. So what do you do?

Building Assessment Provisions

The Building Assessment Provisions below are found in Section 30 of the Building Act 1975.

The Building Assessment Provisions are the list of provisions that building works is assessed against for compliance in Queensland.

Building Assessment Provisions

  • Integrated Development Assessment System (IDAS)
  • Chapter 3 and 4 of the Building Act 1975
  • The fire safety standard (section 217 of the Building Act 1975)
  • The Standard Building Regulation 2006 or other regulation made under the Building Act 1975;
  • The Building Code of Australia.
  • The Queensland Development Code (QDC). Subject to section 33 of the Building Act 1975
  • Any relevant local law, planning scheme provision or resolution made under section 32 or 33 of the Building Act 1975.
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