When your home starts to feel cramped, the question arises: do you extend outwards with a single-storey extension, or is adding a second storey the smarter move? For many Melbourne homeowners, choosing the right type of extension is about more than just extra space — it’s about lifestyle, property value, and long-term flexibility.

Whether you’re after a bigger living area, an extra bedroom, or just breathing room, this guide explores the pros and cons of single-storey vs two-storey extensions to help you make a confident decision for your home.

Understanding the Basics: Extending Up vs Out

Before diving into numbers, aesthetics, or regulations, it’s important to understand what each storey extension involves.

• Asingle-storey extension expands your home outwards, often into the backyard or side of the property. These are typically used for open-plan kitchens, dining rooms, or an additional ground-floor bedroom.
• A double-storey extension, or second-storey addition, builds upwards, adding a full floor to your existing layout. It’s ideal if your land size is limited or you want to retain your outdoor area.

Each option requires careful planning, budgeting, and approvals — particularly in Melbourne, where local council regulations and block sizes vary greatly.

Single-Storey Extension: The Grounded Choice

Pros of a Single-Storey Extension

• Simpler structural work: No need for major foundation reinforcement or roof removal.
• Faster approval process: Many single-storey extensions fall under streamlined planning regulations, making it easier to get approval.
• Cost-effective per square metre: Typically cheaper than building up, especially with straightforward designs.
• Less disruption: No scaffolding, no relocating during the build — often, families can stay home during construction.
• Great for open-plan living: Extending the rear or side allows for expansive layouts with better indoor-outdoor flow.

Cons of a Single-Storey Extension

• Takes up land: You’ll sacrifice backyard or garden space.
• Potential to overshadow neighbours: Especially with side extensions, careful design is needed to comply with sunlight access rules.
• Layout limitations: You’re restricted to existing roof heights and ceiling levels unless the roof is restructured.

Single-storey extensions offer a practical and budget-friendly way to extend your home, especially if you have a generous block and want to avoid a lengthy construction process.

Two-Storey Extension: Reaching New Heights

Pros of Adding a Second Storey

• Preserve outdoor space: Perfect for homes on smaller blocks or those wanting to retain their garden or entertainment area.
• Maximise views and light: A second-storey can unlock better views and natural light with well-placed windows or balconies.
• Add significant value: A well-designed double-storey extension often boosts property value, especially when it includes extra bedrooms, bathrooms, or even a retreat area.
• Future-proofing: Great for growing families who want to stay long-term without compromising on lifestyle.

Cons of a Two-Storey Extension

• More complex structural requirements: You’ll need to assess your foundation and walls to ensure they’re structurally sound for the added load.
• Longer approval timeline: More likely to require a detailed building permit, full architectural drawings, and extra council regulations scrutiny.
• More costly: Per square metre, a second-storey is generally more expensive due to the need for specialised labour, scaffolding, and reinforcement.
• Temporary relocation: In many cases, you may need to move out during the build, depending on the extent of structural work.

If you’re adding a second storey, expect a longer timeline, but also a potentially more impactful result — especially in suburbs where land is scarce and upward growth is more practical.

Cost Considerations: Single vs Double Storey

In Melbourne, a single-storey extension may range from $2,000–$4,000 per square metre, depending on finishes, access, and design. A double-storey extension typically starts around $3,000–$5,500 per square metre due to the additional complexity.

Other factors influencing price:

• Structural modifications
• Roof removal and replacement
• Scaffolding and safety measures
• Custom features or premium finishes
• Site access and slope

Be sure to get quotes from experienced home builders who understand your block’s potential, council zoning, and design preferences.

Approval and Council Requirements

Whether you decide to extend upwards or outwards, your home extension must comply with local council planning and building regulations in Melbourne. Key considerations include:

• Setbacks from property boundaries
• Overshadowing controls, particularly for second-storey additions
• Height restrictions based on zoning
• Heritage overlays, if your home is in a protected area

In most cases, a building permit is required, and depending on the design, scale, and location of the extension, a planning permit may also be necessary — especially if the project impacts neighbouring properties’ access to sunlight or privacy.

It’s essential to consult with a building designer, architect, or planning professional to ensure your plans are compliant from the outset, avoiding unnecessary delays or revisions. For a deeper dive into what’s involved, see Expanding Your Home: Understanding Limits and Permissions.

Which Is Right for You? Key Factors to Consider

Choosing between a single-storey and two-storey extension depends on several personal and practical factors:

• Block size: Smaller block? Upward is usually better.
• Outdoor lifestyle: Love entertaining outdoors? Preserve your yard with a second storey.
• Budget: Ground-floor extensions are usually cheaper and quicker.
• Timeline: Going out is faster; going up is more complex.
• Neighbours: A second storey may trigger more objections or require privacy screening.
• Long-term needs: Think beyond today — will you need that extra bedroom or study in 5 years?

The Final Word: Build Smart, Build Beautiful

Whether you opt for a single-storey extension or commit to adding a second storey, the key is working with a custom home builder who understands the nuance of Melbourne’s construction landscape. At Karja Builders, we specialise in high-end, architecturally integrated home extensions that enhance your lifestyle without compromising quality or compliance.

We’ll guide you through design, permits, structural assessments, and every detail of the construction process, ensuring your home doesn’t just grow, but evolves with grace.

Considering an Extension? Let’s Talk.

If you’re ready to extend your home, Karja Builders is here to help. Book a consultation with our expert team to explore your options, discuss costs, and begin the journey to a more spacious, more beautiful home.