Post a job

How much does a second storey addition cost? | 2020 cost guide

13th Dec '19 • By Jared Jeffery

We have seen some jaw droppingly spectacular second storey addition costs designed and built by our tradies. However time and time again, one question seems to be the make or break - how much is it going to cost? So we are going to tell you, right now!

Estimates vary but on average a second storey addition costs between $1,850 and $15,000 per square metre. 

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 right off adding a second storey to their home due to expenses and hassle, at we think you need to consider every avenue. After all, wouldn’t it just be SO much easier to expand on what you have already got rather than uproot the whole family somewhere else? 

We have seen some jaw droppingly spectacular second storey addition costs designed and built by our tradies. However time and time again, one question seems to be the make or break - how much is it going to cost? So we are going to tell you, right now! 

Get Carpenter quotes now

Article Overview 

  • How much does a second storey addition cost? 
  • What to consider when adding a second storey?
  • How to add a second storey?
  • Choosing the right contractor for your second storey addition
  • Second storey addition FAQs

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 undoubtedly a massive investment for homeowners, however it is also a big cost-save! As the main alternative to adding a second storey is typically buying a new house altogether. 

To receive the most accurate quote for your specific second storey addition you should seek quotes from several different builders and as a rule of thumb add about 20% to your final price. 

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 are the first and foremost consideration 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 to take it down! 

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, 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 homes 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, timeline, timeline. How long is it going to take? Well 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 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 on 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?

So you have an idea of price, you know the main factors you are going to take into consideration and now you are wondering how exactly one goes about adding a second storey? Lucky you have us! 

We highly recommend taking out insurance for any accidents that may occur during construction or check that your contractor accepts liability in their contract. As we stated earlier, add 20% to your budget to allow for the unexpected (you will thank us later). 


Choosing the right carpenter for your second storey addition

Straight up - this is NOT a DIY project. Do not even try it, just don’t. You will need to hire a builder for this task and possibly an architect. Browse through industry experts available in your area on 

So as we mentioned earlier, take multiple quotes!! Do your research (yes reading this article counts, so good on you) 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? 

Get Carpenter quotes now

Second storey addition FAQs

Do I need to arrange design and plans for council approval?

Yes you should definitely ensure your designs/plans are council approved. Some builders may offer to do this for you as part of their service. 

Who can I talk to during construction if I have any questions? 

This is a great question to ask your builder when taking a quote, typically the project manager is the person on site that you can talk to. 

How long will it take to build my second storey extension? 

This depends on your individual home and needs, but anywhere from two months to a whole year. 

How soon can work on my project start?

Again, check with your builder but usually once council approval is received and you have signed your contracts work begins four weeks later. 

What hours do the tradespeople generally work on my home? 

With most projects, you can expect tradespeople between the hours of 7am and 4pm. Discuss this with your builder and make any necessary arrangements. 

Will the extension blend in with my existing house? 

As a general rule, if you have designed the extension to blend with your existing home’s design, then yes it will! If you have planned something different from the rest of the home then it probably won't blend. Again, discuss any concerns surrounding this with your builder - they are there to help! 

Can I still live in my home during construction? 

With the majority of extension projects, yes you are able to remain living in your home bar perhaps a few days. This will be communicated by your builder if necessary.

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


Other Cost Guides


Posted under