How much does a second-storey addition cost? 2025 cost guide

There are a number of reasons homeowners may consider adding a second-storey addition to their home. Whether that is to allow for a growing family, to move a grandparent in, to have more space for guests or even to allow for an awesome rec room. The options are limitless! While many homeowners write off adding a second storey to their home due to expenses and hassle, at Service.com.au we think you need to consider every avenue. After all, it's often easier to expand on what you have already got rather than uproot the whole family somewhere else.

How much does a second-storey addition cost?

Estimates vary, but on average a second-storey addition costs between $1,850 and $15,000 per square metre. The total price depends on a number of factors such as the complexity of the job, chosen materials, tradies rate and access to your property. Adding a second storey is a massive investment, but compared to buying a new property it can be a cost-effective option. While a ground floor extension might be simpler in some cases, a second storey extension allows you to create more space without sacrificing your backyard or outdoor space.

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To receive the most accurate quote for your specific second-storey addition you should seek quotes from several different builders.

What to Consider When Adding a Second Storey

There are a few key considerations to take into account, outside of cost, when planning for a second-storey addition. These include building regulations, foundation, design, timeline and alternative living space.

• Building regulations: These are the first and foremost considerations prior to anything else! You should check with your local zoning office or council as to any height restrictions or so forth. After all, there would be nothing worse than building a stunning new storey only to be told it doesn't meet standards.
• Foundation: Check what you currently have and if it can handle the additional weight that will come with another level. This is a safety requirement and if your foundation is not strong enough you may need to have it reinforced or even ditch the second-storey addition and install a ground-floor extension.
• Design: This is an important part of the second-storey addition process, during which you should consider the fundamentals, such as whether your existing fittings need changing, if this addition will add to your home's look and what metrics you want. A builder or architect can be extremely helpful during this part of the process; after all, this is what they are qualified for!
• Timeline: How long is it going to take? For some second-storey additions, it can take as little as 12 weeks and for others over a year. This is a question best posed to your builder. Keep in mind that quality cannot be rushed!
• Alternative living space: This is often overlooked by many homeowners, but during the installation of your second storey you may have to vacate the premises. There may be certain rooms blocked off and a lot of noise that can impact your day-to-day life. Consider if you need a few days away or how you can best deal with the interruption.

How to Add a Second Storey?

Now you have an idea of price and you know the main factors you are going to take into consideration, you're probably wondering how exactly to go about adding a second storey. We highly recommend taking out insurance for any accidents that may occur during construction or check that your contractor accepts liability in their contract. We also recommend factoring in potential hidden costs when budgeting. Storey extension costs often run over the initial estimate due to unforeseen challenges, so adding around 20% to your budget is smart.

Choosing the Right Carpenter for Your Second Storey Addition

A second-storey addition is not a DIY project. You will need to hire a builder or carpenter for this task and possibly an architect. Browse through industry experts available in your area on Service.com.au.

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As we mentioned earlier, get multiple quotes. Do your research and ensure you know what to discuss when meeting with builders. We recommend asking prospective contractors the following questions:

• Are you qualified for this job?
• Do you have references I can check?
• Are you insured for this job?
• Will you be liable for any damages that may occur?
• How long do you expect the job to take?
• Will you provide me with a written quote?
• Do you have examples of similar jobs you have done?
• Can you outline my storey extension costs?

If you have any further questions, we recommend openly asking your builder or enquiring with one of the many contractors available on Service.com.au.

Final thoughts

Second storey extension costs may seem daunting, but the long-term benefits can outweigh the expense. By investing in a second storey addition, you’re not only creating more space for your family, you’re also likely increasing your property value. Whether you’re dreaming of a new master bedroom, a home office, or simply more living space, adding a second storey can transform your home without the hassle of moving. Compare your options carefully, ask the right questions, and weigh the overall cost against the benefits of staying in the home and neighbourhood you already love.

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