Extension house designs are the ideal way to expand your living space without the stress of moving house. These builds can add both style and function, custom-tailored to your lifestyle. In this article, we’ll explore 10 standout extension ideas that not only improve how you live but also add long-term value to your home. Whether you’re dreaming of a sun-drenched home office, a spacious open-plan kitchen, or a stylish deck for weekend barbies, these extension house designs offer practical inspiration.

1. Open-Plan Kitchen-Diner

One of the most popular ways to transform your home is with an open-plan kitchen-diner. By knocking down internal walls, you can create a welcoming, free-flowing space that encourages family connection and makes entertaining easier. It’s perfect for modern living—whether you’re prepping dinner while chatting with guests or keeping an eye on the kids as they do homework.

Open-plan designs also invite plenty of natural light. Incorporating skylights, floor-to-ceiling windows, or bi-fold doors can create a fresh, airy atmosphere. This style of layout not only improves day-to-day functionality but can also add serious value to your property. Plus, it’s easy to customise with built-in storage, large island benches or comfy lounge zones.

2. Glass Box Extension

For a sleek and contemporary upgrade, a glass box extension offers striking aesthetics and a stronger connection to the outdoors. Featuring floor-to-ceiling glass panels, this type of design frames your garden while flooding the space with sunlight—perfect for a relaxing sitting area, studio, or modern dining space.

Glass box extensions create visual impact and enhance wellbeing by maximising daylight. With quality insulation and glazing, they can also be energy-efficient. The transparency adds a sense of openness, making even a smaller footprint feel spacious.

3. Two-Storey Extension

Need more room to grow? A first-floor extension effectively doubles your floor space and gives you flexibility for bedrooms, bathrooms, or even a second living area. It’s a smart option for growing families who want to stay in their current neighbourhood.

This extension house design also allows for zoned living—separating communal areas downstairs from bedrooms or study spaces upstairs. Whether you’re after a seamless modern build or something that mirrors your home’s original character, a good builder can ensure a cohesive design that looks like it’s always been there.

4. Loft Conversion

A loft conversion is an excellent way to make use of otherwise wasted roof space—ideal in city homes where land is limited. It can be transformed into a bedroom, office, or retreat without changing your home’s footprint.

Lofts offer privacy and tranquillity, perfect for a parent’s retreat or guest space. With skylights bringing in natural light, they’re ideal for a peaceful, inspiring environment. Plus, they add value by increasing your usable space and bedroom count—highly attractive to buyers.

5. Side Return Extension

Popular in Victorian and Edwardian homes, a side return extension uses the often-unused space along the side of your house. This compact extension can have a big impact—opening up kitchens, dining areas, or living rooms.

Design-wise, it’s a chance to bring in more natural light with roof windows or glazed doors. You can opt for a traditional or ultra-modern look, depending on your taste. With clever planning, this style of extension delivers a surprisingly large return on space and functionality.

6. Rear Extension

Extending out the back is a classic option for homeowners wanting more space without drastically altering their home’s footprint. Whether you’re adding a large kitchen, a living room, or dining area, a rear extension offers versatility.

Maximise flow by incorporating sliding or bi-fold doors to blend indoor and outdoor spaces. With smart design, a rear extension can improve how you live while offering excellent bang for your buck. It’s also a relatively straightforward project that can boost your home’s resale value.

7. Alfresco room

An alfresco room is a stylish and relaxed way to add extra space to your home. These semi-enclosed or fully enclosed areas are designed to connect your indoor lifestyle with outdoor living, perfect for entertaining year-round. With large sliding doors or louvres, you can enjoy natural light and fresh air while staying protected from the elements. Whether it’s used for casual dining, lounging, or hosting friends, an alfresco space brings flexibility and a real sense of ease to your home.

8. Garage Conversion

Got a garage you barely use? Transforming it into living space is a cost-effective way to expand your home. Garage conversions are great for an extra bedroom, office, or rumpus room.

Because you’re working with an existing structure, it’s often more affordable and quicker to complete than other builds. Match it to your home’s exterior for a seamless finish and enjoy the boost in functionality and property value.

9. Indoor-outdoor living area

An indoor-outdoor living area is another popular option in Australian homes, especially in warmer climates. These spaces blur the line between inside and out, creating a seamless flow to your backyard or courtyard. With thoughtful design, you can enjoy fully retractable bifolds, covered decks or sun-drenched rooms that still feel part of the landscape. They’re perfect for everything from a morning coffee spot to a relaxed afternoon with a good book—while making the most of the Aussie lifestyle.

10. Wrap-Around Extension

Want the lot? A wrap-around extension delivers maximum space by extending both the side and rear of your home. The result is a generous open-plan layout perfect for kitchens, lounges, or multi-use family zones.

This design maximises your block and integrates beautifully with gardens or courtyards. With thoughtful planning and design, a wrap-around extension can completely transform your home’s functionality and street appeal.

Choosing the Right Builder for Your Extension

Selecting the right builder can make or break your extension house project. Start by asking around for recommendations and checking online reviews. If possible, visit completed projects or speak with past clients to get a real sense of a builder’s quality and professionalism. It’s also essential to ensure your builder is licensed, insured, and experienced in home extensions. Membership with recognised industry bodies like the Master Builders Association is a strong indicator of credibility.

Communication is just as important—choose a builder who’s approachable, transparent with pricing and timelines, and keeps you updated throughout the process. Always get a written contract that clearly outlines the scope of work, key dates, costs, and any warranty details to avoid surprises down the track.

And don’t underestimate your gut feeling. You’ll be working closely with this person, so make sure they’re someone you trust and feel comfortable with.

Ready to start your extension house journey? The experienced team at Wal Robbins is here to help you design and build with confidence. Whether you’re planning a sleek modern extension or a classic family-friendly renovation, we’ll bring your vision to life with precision and care.