Single-Storey vs Double-Storey Extensions: Which Is Right for You?

Are you thinking about extending your home but not sure whether to spread out with a single-storey extension or build up with a double-storey extension? And if you could understand the pros and cons of each option in simple terms before you spend a cent, would that make saying “yes” to the right choice a lot easier? Home extensions in Australia aren’t one-size-fits-all. The best option for you depends on your block size, budget, council rules, and how your family actually lives in the space. 

Let’s compare single-storey vs double-storey extensions, looking at cost, design, space, and lifestyle, so you can make a clearer decision about which type of extension is right for your home.

How do single-storey and double-storey extensions compare?

When you’re choosing between a single-storey and a double-storey extension, you’re really choosing how you want to add space to your life, outwards or upwards. Here’s how they stack up in simple terms.

1. Space and layout: How do you want to live day to day?

Single-storey extension – spread out living

• Great for creating bigger open-plan living, dining, and kitchen spaces on the ground floor.
• Perfect if you want an easy indoor–outdoor flow to a deck, alfresco, or garden.
• Works well for families who like everyone on one level, with kids playing nearby while you cook or relax.

Double-storey extension – separate zones

• Ideal for adding bedrooms, a parents’ retreat, or a home office upstairs.
• Helps create more privacy between living areas and sleeping areas.
• Good if you want quieter spaces away from the main living zone (e.g., teens upstairs, adults downstairs).

Think:

• If you want a bigger, open living space, a single-storey often makes more sense.
• If you want more rooms and clear “upstairs/downstairs” zones, a double-storey is often better.
  

2. Cost and complexity

Single-storey extension

• Usually cheaper per square metre to build than a double-storey, because the structure is simpler.
• Often has fewer structural changes to the existing roof and framing.
• Still needs solid foundations, but it may be easier if the site is flat and accessible.

Double-storey extension

• Can be more expensive per square metre, because you’re adding another level, stairs, and more structural work.
• Often involves strengthening the existing house to carry the extra load.
• May require scaffolding, more complex engineering, and potentially longer build times.

However, a double-storey can sometimes give you more total space on a smaller footprint, balancing out the overall value.

3. Impact on your yard and outdoor space

Single-storey extension

• Uses more land area, so you’ll lose more of your backyard or side yard.
• Can reduce lawn or garden space, which might matter if you want a play area, pool, or veggie garden.
• Best suited to blocks with ample outdoor space.

Double-storey extension

• Adds space without taking up as much ground area, so you keep more of your yard.
• Helpful on small or narrow blocks where outdoor space is already limited.
• Good if you want to keep room for kids, pets, a pool, or entertaining outside.

If outdoor space is important to you, building up instead of out can be a big advantage.

4. Council, height, and overlooking

Single-storey extension

• Often easier in terms of privacy and overlooking neighbours.
• Still needs to satisfy setback rules and site coverage limits, but usually has fewer issues with height.
• May have a smoother path with neighbours and council, depending on your local rules.

Double-storey extension

• Must comply with height limits, overshadowing rules, and privacy controls.
• Windows on the upper floor may need careful placement or screening to avoid looking straight into neighbours’ yards.
• Sometimes requires a more detailed design to pass council review.

If your area has tight planning controls or your neighbours are very close, design and approvals for a double-storey can be a bit more involved.

5. Access, stairs, and long-term living

Single-storey extension

• No stairs – easier for young kids, older adults, and anyone with mobility issues.
• Better if you’re thinking about aging in place or have family members who find stairs difficult.
• Every day living stays on one level, which can feel simpler and more relaxed.

Double-storey extension

• Always involves stairs, which take up space and may be tricky for some people.
• Can work well if you plan to keep the main living area and at least one bedroom and bathroom downstairs.
• Good for separating noisy and quiet zones, but think about how you’ll use stairs in 5–10 years.

If long-term accessibility is important, a single-storey layout (or one with key rooms downstairs) can be a safer bet.

Choose the extension style that truly fits your life

At Refresh Renovations Australia, we help you work through these choices step by step. We look at your site, your goals, and your budget, then explore both single-storey and double-storey options so you can see the pros and cons clearly before you commit. From design and council approvals through to construction, we manage the process for you so your extension feels like a natural, well-planned part of your home.

If you’re thinking about extending and want expert guidance on whether a single-storey or double-storey extension is right for you, get in touch with Refresh AU. We’ll help you design a solution that suits your lifestyle now and adds real value for the future.