Summary

When an owner wants to make an improvement/alteration to part of the building that is common property (such as in a multi-tier building) or to an area of the Common Property with the intention of the improvement being only for that Owners benefit (such as building a structure in their backyard, where the yards are not part-lots on the Strata Plan), then the following information will assist with this process.

Under common law owners are considered 'tenants in common' in conjunction with the other lot owners of the Strata Scheme.  This means that all owners interests need to be considered when there is an alteration to the use of common property.

For Owners Personal Benefit 
When an Owner wants to alter common property in such a way that they are the only beneficiary of the alteration, they need to seek approval from all owners. ESM's understanding from previous State Administrative Tribunal (SAT) decisions is that if an owner wants to make an improvement to common property, then as tenants in common they require the approval of all other owners. This can be achieved via a resolution without dissent in order to get approval to alter common property for their personal benefit.

For the Benefit of All Owners
When an Owner wants to alter common property in such a way that all owners will benefit from the change, then the approval may be granted via a simple or special resolution at a General Meeting.  
More information about this can be found here.

Lot Alterations
Where are Owner wants to make structural alterations to their lot, they require approval under Section 87/88 of the Strata Titles Act 1985.  
More information can be found here.