Class 1a and Expandable Homes in Queensland
Buyers often ask whether an expandable home "is Class 1a". Classification isn't a label on the product. Your building certifier decides it for your building, on your site, based on how it will be used. This guide explains what that means and what documentation supports the process.
What Class 1a means
The National Construction Code sorts buildings into classes by use. Class 1a covers a single dwelling, such as a detached house. A stand-alone expandable home used as a residence is generally assessed as Class 1a.
A secondary dwelling or granny flat used alongside a main house may be assessed differently depending on how it is used. Class 10a covers non-habitable buildings such as sheds and garages, so if people will live or sleep in the home, expect it to be assessed as a dwelling. Your certifier confirms the classification, and that decides which standards apply.
Component certificates are not building approval
We publish certificates for components used in our homes, such as switches, plug sockets, building wire, toilets and shower sets. These show that those individual products meet the relevant Australian standards.
They do not approve the building as a whole. Building approval covers the complete home on your site, including where it sits, its footings and its connections. Only your certifier can issue it.
| Document | What it covers | Who provides it |
|---|---|---|
| Component certificates | Individual products such as switches, plugs, wiring, toilets and tapware | CYJ supplies these |
| Manufacturing documentation | How the home was built and checked in the factory | CYJ supplies this |
| Building approval | The whole building on your site, including siting and footings | Your private building certifier |
| Connection compliance | Water, sewer and electrical connections on site | Your licensed plumber and electrician |
| Final certificate | Permission to occupy after final inspection | Your private building certifier |
You can download the component certificates from our certifications page and pass them to your certifier.
The approval path in Queensland
In Queensland, building approval is typically issued by a licensed private building certifier rather than by the council directly. The usual order is:
- Check your council's planning scheme for your lot
- Confirm how the building will be used, and therefore its classification
- Engage a licensed private building certifier
- Provide the certifier with compliance documentation for the home
- Complete footings and connections, then pass inspections and final sign-off
The council approval guide covers each step in more detail.
Site work the certifier will look at
Classification is only part of the assessment. Your certifier will also review footings and connections. See the foundations guide and the plumbing and electrical guide to understand what is involved before you talk to them.