Templeton Built

Home extensions represent one of the smartest investments you can make in Adelaide. Whether you’re adding a rear living space to capture those stunning summer sunsets, extending your kitchen into the backyard, or building upwards with a second storey, a well-planned extension transforms how your family lives in your home.

At Templeton Built, we’ve extended hundreds of Adelaide homes across the foothills, the suburbs, and the coast. This guide reflects what we’ve learned about extending homes in our unique climate, with our specific soil conditions, planning rules, and heritage constraints.

Why Adelaide Homeowners Are Choosing Extensions

Adelaide property values have climbed steadily, making knockdowns less attractive than they once were. A thoughtful extension delivers genuine value: you keep the home you’ve built memories in, you improve the way the home works for your family, and you see genuine returns when you sell.

Extensions also give you flexibility that new builds don’t. You can choose exactly where to add space. You can design around existing trees, north-facing windows, or heritage stone walls. You’re working with what you’ve got and improving it.

For many families, an extension is also faster than a knockdown rebuild. You’re not waiting for demolition, site remediation, or all the complexities of building from scratch. Six to nine months, and you’ve got your new space.

Types of Home Extensions in Adelaide

Rear Extensions

The most common extension in Adelaide, and for good reason. A rear extension gives you a new living zone, kitchen, dining area, or combination space while keeping the original home intact. They work beautifully when you’ve got a generous backyard.

In Adelaide’s summer heat, rear extensions facing north and east are prized. You can design with deep eaves, cross-ventilation to neighbouring rooms, and glass orientation that captures winter sun while shading summer heat. This is crucial in our climate.

If you’re in Unley, Norwood, or Burnside, your extension needs to respect the character of the streetscape. Council guidelines typically require materials and proportions that suit the heritage character. That’s not a limitation—it’s an opportunity to enhance your home’s appeal.

Side Extensions

Perfect when your backyard is modest or oddly shaped. A side extension creates a new entry, mudroom, expanded kitchen, or home office without consuming valuable rear space. They work particularly well for narrow blocks.

In blocks under 15 metres wide (common in inner suburbs like Wayville, Parkside, and Clarence Park), a side extension is often the only viable way to add meaningful space. Building controls allow setbacks from side boundaries, and a sympathetic design actually improves the home’s proportions.

Ground Floor Extensions on Sloped Sites

The Adelaide Hills homes sit on slopes. This creates both challenges and opportunities. A skilled builder can tuck a ground floor extension beneath an existing upper level, effectively doubling your usable footprint without the cost or complexity of second storey work.

These extensions require careful site engineering. Our Adelaide soil is reactive clay—it moves with moisture. Sloped sites magnify drainage challenges. Proper footings, site drainage, and waterproofing are non-negotiable. This is where experience with Hills homes matters enormously.

Second Storey Additions

For families needing significant extra space without eating into the backyard, second storey extensions are transformative. They’re also one of the most regulated extension types in Adelaide.

Second storeys trigger stricter planning assessment in many council areas. You’ll need to consider:

• Setback requirements from neighbouring properties
• Building height limits (often 10–11 metres to the highest point)
• Overlooking restrictions—your windows can’t directly overlook neighbours’ private outdoor areas
• Bushfire performance standards if you’re in a CFS bushfire zone (common in the Hills)

The cost is higher than single-level extensions, but the return on investment is also substantial. A second storey can add two or three bedrooms and a bathroom, completely transforming a home’s appeal for families.

For detailed costing on second storeys, our guide on second storey extension costs breaks down typical Adelaide market pricing.

Wraparound Extensions

Some homes benefit from extending on two sides—typically a rear extension combined with a side extension or entry pavilion. These are more complex to plan and regulate but deliver exceptional results when the site and home design allow.

A wraparound creates flow and symmetry. It also allows you to completely reimagine how the home connects to the outdoors, crucial in Adelaide where outdoor living drives property value.

Adelaide’s Planning System: What You Need to Know

South Australia operates under the Development Act 1993 and the Planning & Design Code (which replaced the old zoning system). Understanding how these rules affect your extension is the first step toward a smooth approval process.

Complying Development vs Merit Assessment

Not all extensions require the same approval process. This is important because it affects timeline and cost.

Complying Development extensions meet specific, pre-defined standards. They’re approved by a certifier (typically a building surveyor) within about two weeks, rather than going to council. Complying development extensions are:

• Generally single storey
• Limited in size (often maximum 60 square metres for rear extensions, though this varies)
• Required to meet setback and boundary standards
• Faster and cheaper (no council assessment fees)

Merit Assessment extensions don’t meet complying development thresholds, so they go to your local council for formal assessment. This applies to:

• Most second storey additions
• Large extensions exceeding size limits
• Extensions in heritage overlay areas
• Developments affecting trees or requiring variances in setbacks

Merit assessment takes longer (typically 4–8 weeks) and costs more, but it’s not a barrier. Most Adelaide extensions go through merit assessment and are approved.

Heritage Overlay and Character Zones

If your home is in a heritage overlay or character zone, you have additional responsibilities. This applies to many properties in:

• Unley, Norwood, and Burnside (Stone character homes, Victorian and Edwardian stone and brick)
• Glenelg and Henley Beach (Federation and interwar coastal homes)
• Prospect and Medindie (interwar weatherboard homes)
• Much of the central suburbs

Heritage guidelines don’t prevent extensions—they shape them. Your extension materials, proportions, and style need to respect the original home’s character. This almost always means:

• Matching stone, brick, or cladding to the existing home
• Respecting roofline and proportions
• Setting the extension back slightly or positioning it at the rear so it’s secondary to the original streetscape

Far from being restrictive, heritage guidelines often result in better extensions. They prevent jarring mismatches and protect your neighbourhood’s character—which protects your property value too.

Bushfire Performance Standards

If your home is in a CFS (Country Fire Service) bushfire zone, typically in the Adelaide Hills and scattered fringe areas, your extension must meet specific bushfire performance standards. These cover:

• Ember protection around doors, windows, and vents
• Non-combustible decking within a prescribed zone
• Guttering and under-deck mesh to prevent ember entry
• Appropriate vegetation clearing distances

These aren’t obstacles—they’re protective measures that actually increase your home’s resilience and insurance rating. We factor them into every Hills extension from the beginning.

Adelaide’s Building Environment: Soil, Climate, and Connections

Extending a home in Adelaide requires understanding the specific conditions we build in. Getting this right is the difference between an extension that performs flawlessly for decades and one that settles, cracks, or develops moisture issues.

Reactive Clay Soils

Adelaide’s predominant soil is reactive clay. It expands when wet and shrinks when dry—this is normal, but it demands respectful building practices.

When footings don’t go deep enough, or when drainage is poor, clay movement can crack walls and cause settlement. For extensions, this means:

• Footings must reach below the active clay layer (typically 1.2–1.5 metres deep, but varies by suburb)
• Site drainage must direct water away from footings
• Guttering and downpipes must be maintained to prevent water pooling near foundations

In the Adelaide Hills, where soil and drainage complexity increases, getting foundations right is especially critical. Sloped sites require additional attention to site water management. This is why we always recommend soil testing before finalising designs.

Summer Heat and Cross-Ventilation Design

Adelaide summers regularly exceed 38°C, and we’re often reliant on natural cooling. An extension that ignores ventilation and solar orientation will cost a fortune to cool and be uncomfortable.

Smart extension design means:

• North-facing openings: Maximise winter sun, minimise summer heat through deep eaves (typically 600–800mm for living areas)
• Cross-ventilation: Position windows to create air movement between rooms
• Thermal mass: Polished concrete floors or exposed brick absorb heat by day and release it at night
• High ceilings or ceiling fans: Allow hot air to rise and circulate
• External shading: Pergolas, shade sails, or vegetation on western and northern sides

These design choices are invisible in the plans, but they’re felt every day when your energy bills are lower and your home stays comfortable without constant air conditioning.

Connecting Old to New: Materials and Framing

When you extend a 1920s stone home or a 1980s brick veneer, you’re joining two different construction systems. Getting this connection right prevents problems later.

Stone and heritage brick homes: These have solid stone or brick walls (no cavity). Your extension will typically have a cavity wall with insulation. The junction needs proper detailing—a professional damp-proof course, flashing, and attention to how the two wall types work together thermally and structurally.

Brick veneer homes (most post-1960s): The existing home has a brick outer skin with timber framing behind. Your extension should maintain this system, but the connection must be properly tied—typically with stainless steel wall ties and careful planning of the junction line.

Weatherboard or weatherboard-clad homes: Extensions need to match or sympathetically contrast with the existing cladding. The underlying framing and wall structure must connect securely, and weatherboard needs to be properly installed for longevity.

These connections might seem like details, but they determine whether your extension looks and performs seamlessly with the original home.

The Cost of Home Extensions in Adelaide: 2025–2026

Extension costs in Adelaide vary significantly based on type, location, and site complexity. Here’s what you can expect in the current market.

Single-Storey Rear Extensions

Basic rear extension (modest finishes, standard site conditions): $2,500–$3,500 per square metre

Mid-range extension (quality finishes, good design, standard site): $3,500–$5,000 per square metre

Premium extension (high-end finishes, architectural detail, complex connections): $5,000–$7,000+ per square metre

A 30 square metre rear extension on a standard suburban site in Adelaide typically costs $75,000–$210,000 depending on finishes and complexity.

Side Extensions and Entry Pavilions

Side extensions cost similarly to rear extensions per square metre, though they’re often smaller (12–20 square metres). A modest side extension runs $30,000–$100,000 depending on scope.

Second Storey Additions

Second storeys are more expensive, typically $4,500–$8,000+ per square metre because they require stronger foundations, more extensive site work, and longer timelines. A 50 square metre second storey addition typically costs $225,000–$400,000+.

For a detailed breakdown of second storey costs, see our second storey extension cost guide.

Cost Factors That Matter in Adelaide

• Site slope: Hills homes cost more (site prep, drainage, footings)
• Soil type: Clay-heavy sites may require deeper or more expensive footings
• Heritage status: Character homes require sympathetic materials and detailing, usually adding 10–15% to cost
• Connection complexity: Tying into stone walls costs more than modern brick veneer
• Finishes: Choosing quality joinery, appliances, and finishes dramatically affects total cost
• Timeline: Fast-tracking a project increases labour costs
• Site access: Narrow blocks with limited access cost more to build on

Getting Your Budget Right

Always add a 10–15% contingency to your budget for unforeseen conditions—especially in Adelaide, where reactive clay and site drainage surprises are common. Get detailed quotes from builders with local experience. The cheapest quote isn’t the best value if it’s based on incomplete site understanding.

The Extension Process: Step by Step

From your first idea to moving into your new space, here’s what to expect.

Step 1: Concept and Planning (2–4 weeks)

Start with clear thinking about what you want. More space? A new kitchen? A home office? Better flow? This shapes every decision that follows.

Get a site survey if you don’t have one. Understand your block size, slope, orientation, soil type (if possible), and where utilities run. This information guides design.

Engage a designer or architect to develop initial concepts. They’ll consider planning codes, heritage guidelines (if applicable), and how the extension works with your home’s architecture and your lifestyle.

Step 2: DA Lodgement and Approval (4–12 weeks)

Once you have a design, you’ll need planning approval. The timeline depends on whether your extension is complying development (2 weeks) or merit assessment (4–8 weeks typically).

During this phase, you might face requests for changes—setback adjustments, heritage detailing, or neighbour concerns. This is normal. A skilled designer and builder handle these interactions professionally.

Approval in Adelaide is usually granted. The planning system exists to ensure developments fit the neighbourhood and comply with standards. Most extensions do.

Step 3: Detailed Design and Building Approval (4–6 weeks)

Once planning is approved, detailed architectural drawings are prepared. These go to the building surveyor or certifier for building approval, ensuring the design complies with the Building Code of Australia and safety standards.

Your builder finalises materials, colours, and exact specifications. This is also when soil testing and site investigations (if needed) happen, informing final footing and drainage designs.

Step 4: Construction (4–9 months typical)

Building begins with site setup, usually a temporary fence around the work area and facilities for workers. Existing structures are carefully protected.

Then comes the sequence: excavation and footings, frame and roof, weatherproofing, internal fitting (electrical, plumbing, insulation), and finishing.

In Adelaide’s climate, timing matters. Building through winter is common and allows natural drying. Building in summer requires careful dust and weather management but is possible.

You’ll have regular inspections—critical stage inspections by the building surveyor at key points (excavation, frame, pre-plaster, final). These ensure code compliance and give you confidence the work is sound.

Step 5: Connection and Finishing (6–12 weeks final phase)

As the extension nears completion, connections to the existing home are finalised. Services are connected, walls are decorated, and landscaping happens.

Your builder conducts a thorough handover walk, addressing any final punch-list items. Once you’re satisfied, you sign off and the building is certified as complete.

Adelaide Suburb-Specific Considerations

The Adelaide Hills (Heysen, Mount Barker, Handorf, Cherry Gardens)

Hills homes have character, views, and natural beauty—and they have building challenges. Sloped sites mean complex site works. Reactive clay and water management are critical. Many properties are in bushfire zones requiring special building standards. Heritage homes demand respectful extensions.

Budget for deeper site investigation, more sophisticated drainage design, and careful attention to bushfire performance and soil mechanics. Extensions here typically take longer but result in stunning homes that work beautifully with the landscape.

Inner Heritage Suburbs (Unley, Norwood, Burnside, Prospect)

Your beautiful 1920s stone home or elegant Victorian brick comes with heritage responsibility. Extensions need to respect character. But character-sensitive extensions actually enhance property appeal and value.

Expect heritage guidelines to influence material selection and design proportion. Work with designers experienced in heritage extensions. The result is seamless—your extension looks like it belongs.

Coastal Suburbs (Glenelg, Henley Beach, Seacliff, Aldinga)

Coastal properties face salt-air corrosion, sand-blown finishes, and wind exposure. Extensions need durable finishes—stainless steel hardware, quality paint systems, robust joinery. Roofs take a battering; quality installation and maintenance matter enormously.

Design for breezes and sea views. Many coastal extensions are designed to capture that salt-change lifestyle—outdoor living spaces, ventilation, and connection to the coast.

Suburban Sprawl (Woodcroft, Flagstaff Hill, Morphettville, Mount Barker surrounds)

Most newer suburbs have standard soil conditions and straightforward planning. Extensions here are often simpler and faster. Design focus shifts to lifestyle—creating the spaces that suit modern family living.

Choosing the Right Builder for Your Extension

Your builder makes the difference between an extension that’s functional and one that’s beautiful, durable, and a joy to live in. Look for:

• Local experience: A builder familiar with Adelaide soils, climate, and planning system is worth their weight in gold
• References in your suburb: Ask for examples of extensions they’ve done in similar homes
• Communication style: You want a builder who explains options, manages expectations, and keeps you informed
• Attention to detail: Visit completed projects. Are the connections seamless? Are the finishes quality?
• Warranty and aftercare: Ask about defects liability periods and how they handle issues post-handover

At Templeton Built, we’ve spent years learning how to extend Adelaide homes well. We understand the local soil, the planning system, the climate, and how to create extensions that work beautifully with existing homes across all suburbs. If you’d like to discuss your extension plans, we’re here to help.

Common Extension Questions Answered

Will an extension increase my property value?

Yes—thoughtfully designed extensions almost always increase property value more than their cost. A well-designed 30 square metre extension costing $120,000 typically adds $150,000–$200,000+ in value, depending on the home and suburb.

How long does planning approval take?

Complying development: 2 weeks. Merit assessment: 4–8 weeks typically. Complex applications or applications requiring neighbour consultation can take longer, but this is rare.

Can I live in the home while it’s being extended?

Yes. Dust and noise are inevitable, but a professional builder manages impact. Some families relocate temporarily for comfort; others stay. It depends on your tolerance and the extension size.

Do I need to worry about connecting to the existing roof?

Only if you’re extending beyond a certain depth or adding a second storey. Single-storey rear extensions typically have their own independent roofs. A skilled designer integrates the roofline so it looks intentional and unified.

What if my extension finds unexpected issues (poor soil, old pipes, hidden timber damage)?

This is where contingency budgets matter. Quality builders factor in site investigation and build flexible timelines. If unexpected issues emerge, they’re managed professionally and communicated clearly. It’s rare that surprises derail a project completely.

Next Steps: Getting Started on Your Extension

If you’re considering an extension, start by asking yourself: What does your home need? More space? Better flow? A new kitchen? Once you’re clear on your goals, you’re ready to explore options.

Consider browsing our detailed guides on second storey extension costs, or exploring the broader landscape of knockdown rebuild options if you’re still weighing extension versus rebuild.

When you’re ready to discuss your specific home and vision, we’d love to help. Templeton Built specialises in custom home extensions across Adelaide, and we’ve helped hundreds of families create the homes they love through thoughtful, well-executed extensions.

Get in touch with us for a free consultation. We’ll talk through your goals, your home, and what an extension could mean for your family and your property. There’s no obligation—just honest advice from people who love building beautiful homes in Adelaide.