Home » Blog » How Long Does it Take to Build a Duplex?

Duplexes are fantastic options for real estate investors looking for long-term, high-return rental opportunities, or for family units looking for their next family home on one side, with a rental on the other side of a split duplex. They offer design flexibility of either a stack or side-by-side and take up less land space than traditional houses, making them great options for a house and land package deal.

If you’re looking at building a duplex and wondering how long it takes to build one, then this article is for you. What is the duplex construction schedule? What are the factors that can affect the building timeline for a duplex? (And how can you avoid or mitigate them!?)

Let’s explore the construction timeline for a duplex! To give you all the information you need to get started on your custom-built duplex in Sydney.

How Long Does it Take to Build a Duplex?

Undoubtedly, it takes a lot of time to build a duplex, with an average timeline of between 12 and 18 months. This is because building a duplex is complicated, even for the simplest of designs, duplexes are large dwellings that house two groups of people, each needing their own sewage, plumbing and electrical system, water hookups, heating methods and so on.

Let’s walk through the initial phases of duplex construction, and then explore how to expedite the building duration for a duplex.

Site Preparation and Permitting

Before any construction project can take place, the following site preparation steps need to be taken and subsequent reports generated.

  • Site Surveying

The first step in any site preparation is for a professional surveyor to come to the site of your build and mark your property lines, prepare a site map to provide to your builder, as well as answer any questions you may have about easement necessities (how far back your duplex has to be from access roads, etc).

  • Testing & Analysing Soil Samples

Collecting and testing soil samples is the job of a geotechnical engineer. These individuals work for your city council and will come to your site to collect and test soil samples for elements that would be harmful to you to ingest, drainage capabilities, depth, and suitability for foundation work.

They’ll generate a report that you’ll have access to and make a recommendation to the city council. The council will review the report and (hopefully) green-light your project!

  • Clearing of Land

Once you’ve received a green-light from your city council, your duplex builder can begin clearing land if necessary. If you’ve purchased “raw land”, there’s every chance that it hasn’t been levelled yet and/or is full of obstructions that hinder building or make laying any foundation impossible. Land-clearing operations usually take about a month, depending on the size of your block.

  • Site Design Phase

The site design phase consists of discussing and cementing the orientation of your duplex with your builder, building driveways and roads if necessary, drainage ditches, and/or a septic field, and usually consulting with your architect.

  • Levelling of Site for Foundation Preparation

Once you’ve settled on how your construction site (aside from your home) will look, your duplex builder will set about levelling the site for foundation preparation and laying your concrete slab foundation. This will require heavy construction equipment and could also take a couple of weeks, depending on the site’s grade and how level it was initially.

  • Utility Connections

Once you have a levelled building site, construction electrical connections can be run from the power poles to your home and hooking up water and sewage lines. This is the final step before the foundation can be laid and your building construction for a duplex can officially begin!

Tips For Expediting Duplex Construction

Here are a few tips to help reduce the duration of your duplex construction.

Make Each Side Identical

Repetition is key to expeditious construction. If you want to expedite your duplex construction timeline, make each side (or each level) identical. It’s easier to do something twice on each level than to make changes when going from one side or level of the duplex to the next. It’s also cheaper to order more materials in bulk for the entire structure than to place orders for different materials.

Keep Your Paperwork in Order

As the owner, you’re responsible for ensuring that site prep and construction permission paperwork are in order. Keep it all together in a neat and organized fashion in a binder or something easily accessible. Keep copies of documents on-site as well so that any inspectors who may pop by have easy access to your approvals for specific parts of the build.

Keep it Simple

While lavish and luxury designs can fetch a higher rental price-tag, importing building materials that are not native to Australia will prolong your build by at least a couple of weeks. Try and keep your design relatively simple if you’re on a time crunch, it will also reduce the overall cost of your duplex design.

Factors Affecting Build Time

Many different factors can affect the building timeline for a duplex, some of these factors are simply unavoidable and the effects of others’ can be mitigated by doing some of the above.

Labour Shortages

The labour shortage in the construction industry in Australia post-COVID has been nothing short of catastrophic. While the government is taking steps to mitigate it, every builder’s worst nightmare is having no-show employees, or critical employees calling in sick, on paternity or maternity leave. Labour shortages are bound to happen at some point. Prepare by extending your leeway on a project by at least a couple of weeks.

Material Shortages

Material shortages are also a huge plague on the expeditiousness of a duplex build! Particularly as duplexes are frequently built using the same materials, you may run into a problem whereby the material your builder was using last week (and needs this week!) is no longer in stock. They’ll need an extra few days to shop around and find a new supplier, further elongating your construction timeline.

Permit Issuances

Another issue you may encounter with your presupposed duration for your duplex construction is the time it takes to get the required permits. Depending on how backed up your town council’s planning offices are, you may be waiting weeks and months for a simple permit to perform a certain step. These are often factored into building timelines issued by builders, but prepare for these rough guidelines to change.

Final Thoughts

As a property developer or home-buyer, you’re choosing wisely by investing in or buying a duplex house. However, the construction timelines for these types of properties may surprise you! Be prepared to wait for your duplex to be completed and don’t try to cut corners to get things done faster.

As builders of duplexes, our commitment to you is ensuring the safe completion of your beautiful new duplex on-time and on-budget, with compromising on the final product. Reach out to Worthington Homes today to get started on your duplex construction.

Frequently Asked Questions

As duplexes are among our most popular custom home designs, we get a lot of questions from prospective clients about how long it might take to build a duplex. Here are some of our most popular!

Can the Size or Design Complexity of a Duplex Affect the Construction Timeline?

Most definitely. Your duplex size and design complexity can significantly impact your duplex construction timeframe. Building a six-bedroom duplex (three on each side) will take longer than a four, or two-bedroom duplex. Additionally, any specialty parts or specialty design elements may take longer to implement if the materials need to be imported from elsewhere in the world, or specially constructed on-site.

Is There a Standard Timeframe for Obtaining Permits and Approvals for Duplex Construction?

It can be difficult to give any standard timeframe for building a duplex, particularly where bureaucracy is concerned. However, the average timeframe for your planning, building and occupancy permits is between 9 and 12 months. A CDC approved duplex through a private certifier however can take 2 – 4 weeks for an approval and is the most logical pathway to take.

How Long Does the Entire Process of Building a Duplex Typically Take?

While it’s important to note that your building time may be longer or shorter, the average time from concept to completion on a duplex build is between 18 and 24 months. Bear this timeline in mind when lining up living accommodations for yourself while your build is taking place, or any timeline you may have given to the public for renting the duplex units (if you’re a landlord).

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