How Much Does It Cost to Add a Second Storey?

April 26, 2022
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The Australian federal government’s HomeBuilder grant available for home renovations got many home owners into thinking about a house extension. That grant looks like a great opportunity to add another storey to a dwelling and thus boost its value and functionality. But how much does it cost to build a second storey?

Will that grant, which is up to a maximum of $25,000, suffice? Let’s talk about house extension costs and two-storey extension ideas Australia builders suggest to wrestle with these questions. 

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How much does it cost to build a second storey?

Building a second storey won’t be cheap, for sure. Exactly how much money you will spend on a second storey addition depends on several cost factors. Its overall price tag will be determined by the size of the floor area, the layout, types of materials to be used, amongst other factors.

There are other basic things to look into before the pencil-pushing to answer how much does it cost to build a second storey.

Firstly, it’s important to check for any building height restrictions in your neighbourhood. Go to your local zoning office for this important information.

The current weight-carrying capacity of your home’s foundation is another basic factor to consider before you can tackle the question—how much does it cost to add a second storey?

Structural engineers or contractors will tell you that some single-storey home builds are not designed to hold up another level.

If this is the case with your house, you need to have it reinforced to pursue the second storey extension ideas Australia homeowners often think about. 

Why not build outwards instead of up?

How Much Does It Cost to Add a Second Storey?

The foundation-reinforcement project is an additional cost that you have to input to settle the question of how much does it cost to add a second storey?

With the added cost of reinforcing the foundation for another floor, you may even consider it smarter to keep it simple and have a ground-floor extension instead.

It becomes a different ballgame should you decide that house extension or building outward is the more viable alternative. You will have to consider the costs of building from the ground up.

These house extension costs include items like excavation, formwork, and concrete costs which can be substantial.

House extension costs comparison

You will have to compare these costs with their expense counterparts in building a second storey. These building-up costs come in the removal of the existing roof cover and framework. There’s also the expense to put down joists and install a new sub-floor and roof. 

In general, these expense items cost less than the prep costs cited earlier on building outwards. Hence, you may be inclined to build upwards rather than extend out.

Another plus for building up is that you don’t have to expand the utilisation of your yard space. But you will also have to weigh some other costs that you will incur when considering the variety of second-storey extension ideas Australia builders propose.

Second storey extension ideas and costs

How Much Does It Cost to Add a Second Storey?

While the construction expense may be lesser when building up than out, you are likely to move out from your house until the second storey is completed. The roof of your home will have to be removed, reconfigured, and reinstalled.

This means you’ll have to relocate and pay rent for a temporary residence. Unless you have a friend or relative who will accommodate you and your family, the rental cost can be substantial for the duration of your home’s second-storey construction.

If you’re building out, you can generally stay put in your home. You will only have to deal with the disruption and debris of the outwards construction. 

Break it down: house extension costs

To weigh the pros and cons of building up or out, you will need a breakdown of all the expenses of both. Pay attention especially to the extra cost of going upwards. 

This can include the fee for a structural engineer. You’ll need this professional to determine if your current house foundation and structure are strong enough to carry the added weight of another floor.

Hiring an architect is another cost factor to look at before you sign a contract to build a second storey. You’ll need the expert eye of an architect to look at how your existing ground floor will match with the new floor.  

To preserve or enhance the curb appeal of your home, the setup and design of existing fittings, like doors and windows, have to match perfectly with those for the second storey. This is but one of the angles an architect will work on for your home’s aesthetics and visual appeal.

Low budget simple two storey house design

Because of the many design options and requirements for a second storey addition, there’s no one-size-fits-all costing solution to such a project. But you can go for a low-budget approach if your house has an attic.

You can convert it into a family room or a bedroom and bath. This approach can give your desired additional space even without a true second storey. You also don’t need to move out while the attic conversion is in progress.

The timeline for such a project will be much shorter compared with adding a second floor. Some contractors estimate that building a second storey can be done as short as 12 weeks for small projects. 

Bigger and more complex second-floor construction, on the other hand, can take over a year to finish. A longer timeline means a higher cost of labour, the rates for which can vary significantly from place to place. 

Cost of second storey extension ideas

Building a second storey may cost less than extending a ground floor, but it will still be a major expense. This is especially so if you adopt trendy designs and high-end materials in the second-floor construction. 

Given the many variables of such a project, its cost estimate falls in a very wide range of $1,850–$3,300 per square metre.

Trimming the cost to as low as possible will be difficult even if you are a handyman with DIY skills that you think can pull off the project. 

Second storey building projects need a team—skilled workers, engineers, and architects. You will also have to keep yourself updated on building tips that can help you reduce costs. 

Want to learn more about building a home?

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