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How Much Does a Second Storey Cost?

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If your home is getting too small for your needs, you have several options. You could buy a new house, add on to the house, or build another storey. So many people in Australia overlook the third option because they think it will be too expensive. However, adding a second storey may not be as expensive as you think, and may actually be cheaper than building a home addition. Let's take a look at the possibilities of building up, the possible costs, and other factors you may need to consider.

Why Build Up?

Adding a second story makes sense if you have little room on your property to expand. Plus, when you build an addition, it will make your out of doors smaller. Yes, your builders will need to perform major construction and remove and replace the roof. However, if you build on, there needs to be a lot of excavation and cement work done, and this can be very expensive. The costs for adding another story can be affordable.

If you decide to add a storey, your home could be unliveable while the roof is removed. It's a good idea to make arrangement for temporary lodging or living conditions during this time. This will make it easier on you, your family, and the building crew.

Estimating Your Costs

With any major building project, you should take the average "per square metre" construction cost into account. If you don't know the exact figures for your location, you can estimate costs. Average construction costs run from about $1850 to as high as $3300 per square metre. These figures vary so much because many things can greatly affect your costs. Here are things that can raise or lower construction costs:

  • Materials - you may wish to include a master bathroom, spa, or other additions.
  • Size - the size of your second story will affect the total costs.
  • Present construction - your original floor may require extensive reinforcement before the project can begin.
  • Additional professional fees - you might want to hire an architect or draftsman to draw up the plans for your new second story.
  • Structural engineer - because your project affects the integrity of the structure you must have a structural engineer approve your plan. This person can work with the designer and construction crew to make sure everything is done to standards.

Figuring Costs for Your Professional Fees

If you hire a draftsman to design and draw up plans for your project, you may pay anywhere from $50 to $100 per hour. Your fees will depend on the kinds of services you receive. Architects are more expensive but they can supervise your project and work with builders and suppliers.

The structural engineer is there to make sure your project meets with local council approval and you won't have structural problems to deal with in the future. These engineers work with builders and supervise important parts of the construction process.

A structural engineer may charge from $100 to $250 per hour for services. Expect to pay on the high side of this estimate, because he may need to create detailed drawings and a report for the local council. It is not unusual to pay $3000 or a little more for services like these. Unlike architects or draftsmen, the services of your structural engineer are mandatory.

Estimating Your Total Costs

Before you call any professional services, you can get a good idea of the costs. First, measure your house and determine the size of your new second story. Now, figure out the square metres of construction required. For example, if the home is 6 X 4 metres you would have 24 square metres. Suppose the average construction cost in your state is $2400 per square meter. 2400 X 24 = $57,600.

Your structural engineer may charge you $4000. But have you forgotten other things? For instance, do you wish to have heating or air conditioning? What about plumbing? Of course you will want stairs. You'll need some type of flooring and it's nice to have windows so you can see the out of doors. Doors are also a good feature to include. These things are not usually part of the square metre construction costs.

Additional Costs

Let's try to get an estimate of these other features to help you better understand the process:

Flooring - suppose you are carpeting a 6 by 4 metre area. If you want to save money and install the cheapest option you might pay $20 per square metre, but let's say you want something better than that and it could cost about $40 per square metre. 40 X 24 (sq metres) = $960. To get a better idea, call some carpet professionals and ask about their pricing selections.


Windows have so many variables it is hard to estimate the costs. But let's say you need 10 average sized double glazed windows and the cost is about $600 each. This would come to $6000.


Costs for stairs can vary so much because there are so many different kinds and sizes to consider. For example, do you want interior or exterior stairs? Plus, it depends on the materials and if you want hand rails or other features. However, even the most inexpensive stairs can cost $5000.

Air Conditioning and Heating

A typical system can easily cost $5000 and as much as $10,000. This depends on the type of system and if you want ducts installed.


There will always be things you don't count on and it could be from 10 to 20 percent of your total costs.

Putting the Numbers Together

Even though these numbers can be considered a "rough estimate", let's put them together to see what we come up with:

  • 6 by 4 metre upper storey construction cost - $57,600
  • Draftsman - 5 hours at $75 per hour - $375
  • Structural engineer fees - $4000
  • Flooring - $960
  • Windows - $6000
  • Air con and heat - $5000
  • Staircase - $5000
  • Subtotal - $78,935
  • Miscellaneous (15 percent) - $11,840

Total - $90, 775

When you talk to a professional builder you will get a much better idea of the costs. In fact, he will help you figure out all your costs and can give you a close estimate. This is important because you may need to obtain financing for the project and you want as close an estimate as possible to the actual costs.

Figures in this article represent possibilities and should not be considered official sources of information.

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