Building a Second Storey: Costs & Considerations

July 1, 2022
Building a Second Storey

Many Australian homeowners consider building a second storey. This thinking can be seen in one report saying Australia boasts the biggest houses in the world, next only to the US. 

Some good reasons are behind why many Australian homeowners want it bigger. With land prices rising, they want to capitalise more on an existing residence and boost its value. 

The popularity of bigger residences and adding a second storey to a house is also reflected in the growth of multi-generational homes in Australia. One research showed that one out of five Australians currently lives in a multi-generational home.

Two-storey extension ideas in Australia thus are plenty amongst the country’s builders. But before engaging any of these contractors, it would be smart to first learn some basics in house extension projects.

Here are commonly asked questions when considering a second-storey addition.

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Does my budget match the second-storey extension cost?

Building a second storey for a house is a major project to budget for well in advance. The estimated cost per square metre of second-storey additions ranges from $1,850 to $3,300, according to some contractors.

The cost is substantial if you do the math just for one-bedroom that in Australian homes averages at 8 square metres. For such a second-storey room alone, you need a minimum budget of about $15,000.

Other factors can bump up the total cost besides the floor size. These variables to consider when setting a budget for building a second storey include the quality of construction materials and labour cost.

You can read our guide to the costs of adding a second storey here.

Will a ground-level extension be more practical?

Instead of building a second storey, you can consider a ground-level extension more practical and less costly. Your final will depend on the type of additional home space you need.

A second-storey extension is ideal if you want additional bedrooms or en suites. On the other hand, extending your outwards is great if you need larger a living area or dining room and kitchen.  

Can my house’s current foundation support a second floor?

You will need to hire a certified structural engineer to answer this question. You will spend more if it turns out your house’s existing foundation isn’t strong enough to support a second floor.

Reinforcing the house foundation will have to be done first and in synch with designing the second-storey floor plans. For such designs, your vertical home expansion project will require a draftsperson or an architect. 

What second-storey extension ideas fit my lifestyle? 

Getting your second-storey extension floor plans professionally drafted is a must. The design drawings will help ensure that the second-storey additions meet your needs and lifestyle.

You have to work with a draftsman or architect in translating your second-floor concept into drawings. In doing so, you will wade through several important elements.

Choosing the placement of the staircase is one on top of this list. The stairs’ position is a crucial factor as their structure will occupy significant space on the ground floor affecting movement at this lower level.

The depth of the stairwell is not only one of the areas for discussion here. Other things to think about are the flow of natural light as well as stairs access and traffic.

Be sure to discuss with your architect as well these considerations when adding a second storey to a house:

  • Optimal ceiling height on the second floor
  • Outwards extension upstairs for maximum added space
  • Taking advantage of overlooking views
  • Enhancing the exterior and curb appeal of the house
  • Strategies for potential cost-saving 

Will my second storey project pass the local building code?

Each local council has drawn up building requirements specifically suited to their localities. In addition, local councils have zoning regulations that among other things may limit building height.

Your builder should be able to help you in getting the necessary construction permit and ensure compliance with the local building code. You have to choose a builder knowledgeable about building second-storey additions. 

The regulations for these constructions can be stricter, especially on second-storey windows. The Building Code of Australia requires safety features like barriers for these windows to prevent the risk of falls. 

Can I remain in my home during construction?

The answer to this question largely depends on the scope of the second-storey additions. Generally, you can remain if it’s a minimal vertical extension involving just a portion of the house gaining a new level. 

However, if the entire house footprint is getting a new floor the scenario changes. In this case, the whole roof of your house will be removed, and hence, you have no choice but to relocate temporarily.

How long will a second-storey extension take?

Building a second storey can be finished within 12 weeks on relatively small projects. Major second-storey additions on big houses, however, can take more than a year.

The bigger projects, aside from their complexity, are also more susceptible to further delays. Because of their longer timeline, these projects can be held back by adverse weather and supply shortages. Cost overruns are also more likely in these projects.

How do I pick the right builder?

The speed and success of your second-storey extension will depend on your choice of builder. You can pick the right through these three key guidelines:

  • Quality. Choose a builder which uses nothing but high-quality construction materials and trusted construction methods. Shortlist those builders who offer guarantees on their workmanship and pick the one with a reputation for structurally sound construction.
  • Experience. Engage a builder with wide experience in second-storey additions. Top-notch builders maintain websites where they present work portfolios that you can check for their quality.
  • Customer satisfaction. Gather contact details of past clients of builders in your locality to gather first-hand experience on their second-storey extension projects. You can also get referrals from real estate agents who have a network in the construction industry. 
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