The ZAC Duplex Difference

The ZAC Duplex Difference

ZAC Homes have been in business 20+ years and within this time we have seen all sorts of residential trends including the evolution of Duplexes (also called Dual Occupancies).

Dual Occupancies are two dwellings on the one block of land and can be attached or detached. Duplexes are a therefore a little more involved than doing a standard single dwelling, but when all you do is duplexes, you get pretty good at it!

Here at ZAC homes we want to make your Duplex process as stress free and simple as possible.


Firstly, you should ensure that Council permits a Dual Occupancy being built on your land. Most Councils will have a minimum lot size or width in which you must meet, in the first instance.

TIP: A current Council Section 10.7 certificate will have information on the permissibility of a Dual Occupancy, as well as information like bushfire or flooding, on the land. A quick call to Councils duty planner will let you know if there is a minimum lot or frontage requirement to build a dual occupancy along with any other special requirements e.g. subdivision. At ZAC we can help you with gathering this information if you need.


At Zac we understand that affordability associated with new developments is expensive. Being prepared for your preliminary plans and tender makes it easier and faster for us to get the ball rolling. Some points to consider are:

Budget: This can be a touchy subject, but the fact is duplexes cost more than a standard home, so budget is a big factor. Once you have an approximate budget, we can then work further with you to estimate your costs.

TIP: Having land that slopes towards the street is less expensive than one that slopes to the rear. Land that slopes to the rear requires a stormwater easement to be created or obtained.

Requirements: Do you need to demolish anything on the land (including removing any trees?) What size of house do you want? What kind of finishes would you like? Do you want to subdivide? Strata? Torrens? All these questions will need to be answered so we can quote packages to suit your needs.

TIP: ZAC homes speciality is duplexes. You can select these from our range (of 17+) or we can customise a duplex to fit not only unique blocks but also your unique requirements.


There are a few differences in the process that set duplexes apart from standard homes.

Hydraulic Plan: The most common misunderstood item is this. All duplex builds require a hydraulic (stormwater) plan designed by a qualified hydraulic engineer. The engineer will work to Councils requirements and other studies produced specifically for your stormwater catchment. The hydraulic plan shows how rainwater will be effectively drained from your land and where will it go. In most cases your hydraulics will also require On Site Detention (OSD) and often add a considerable amount to the overall price.

Landscape Plan: Working in conjunction with the hydraulic plan, Council will also require a Landscape Plan to be prepared by a qualified landscape architect/designer. As above, the landscape plan takes into account Councils requirements and the requirements of the hydraulic design.

The hydraulic design and Landscape plan (and price) cannot be fully worked out until your final plans are drawn and the house is confirmed.


In some cases, Council may have already advised you if no subdivision, Strata Subdivison or Torrens subdivision are permitted with the construction of your Dual Occupancy.  If subdivision is permitted this may be (in most cases) carried out at the same time as the application for the construction of the dual occupancy, or sometime after the dual occupancy is built. Some main differences are:

Torrens: This is the subdivision of one lot into two and there are no shared services.

Strata: If your land cannot meet the requirements for a Torrens subdivison you may be able to Strata title, similar to that of a town house or apartment building. This means that you will need to work with the resident of the other unit for joint concerns (maintaining driveway or roof, etc).

TIP: When you subdivide, you will need the help of a surveyor and / or conveyancer to change the details on the first title and to create an entirely new title that will represent the now separate second property. Once you’re the official owner to two legal residences, you can sell one or both at your leisure.

TIP: Zac covers everything from start to finish with your subdivision so if your undecided with another builder ask the question if they included these in their price?

  • Create additional power pole to both dwellings
  • Create sewer drainage to both dwellings
  • Additional NBN connections
  • Torrens / Strata subdivision plan
  • Final Torrens survey
  • Endeavour energy notice of arrangement
  • Endeavour energy Torrens application
  • Telstra arrangements letter
  • Stormwater provisions
  • Overhead wiring connections
  • New sewer junctions
  • Water service to dwelling
  • Strata title works to be carried out
  • Separate metering of services (electricity, sewer, water, gas)


We have been building duplexes for 20years + and specialise in knowing the best construction methods and giving the best advice for our clients. Key factors why our clients continue to build with us are:

  • Extensive range of 17+ duplexes
  • Broad range of façade options available
  • Customisation to suit your budget and requirements & Council
  • A Complete package price
  • Being upfront from your first meeting
  • Stress free process
  • Always updated throughout the build and council approvals

I hope this article helps answer any questions you may have with duplexes.

Category: Duplex | Tags: , , , | Comments: 0

…ZAC Homes kept us regularly up to date with the progress of our home and the job was finished on time, which was very important to us. We are one hundred percent happy with our home and can thoroughly recommend ZAC Homes and their crew to anyone contemplating building a home.

Bilynda & Paul Robins

…Firstly I would like to thank the ZAC homes team for the experience that my wife and I have had when making the purchase of an investment property. The professionalism and dedication that was displayed, was by far the best that we have seen or experienced previously.

Bob F.

I can not speak more highly of this local building company. Right from the beginning they have been excellent to deal with…The finishes were very good and any work that I wanted fixed which was minor things was done


Very well managed with no hidden cost or surprises. Workmanship was excellent and very professional


Really pleased with the building process, communication and designs. Would definitely recommend.

Hannah Johnston

The customer service and assistance was superb with quick turn around times and patience with our queries. Everything from initial consultation, to colour selection to hand-over was organised easily and open communication was maintained throughout the process.

Daniel North