How Much Does It Cost to Add a Second Storey in Perth?

If your Perth home is starting to feel too small, adding a second storey can be a practical way to create more living space without giving up your backyard or moving to a new neighbourhood.

But before deciding to build upwards, one of the biggest questions homeowners ask is: how much does it cost to add a second storey?

There is no single price that applies to every home. The cost of a second-storey addition depends on factors such as the size and design of the extension, the existing structure, structural requirements, materials, finishes, plumbing, approvals and the level of work required to integrate the new floor with your existing home.

Understanding these factors can help you plan your project and make a more informed decision about whether a second-storey addition is right for your Perth home.

How Much Does It Cost to Build a Second Storey?

The cost to build a second storey varies from one property to another.

A smaller addition creating two bedrooms may have very different requirements from a larger extension incorporating a master suite, ensuite, additional bedrooms, an upstairs living area and balcony.

The existing home is also an important consideration. The structure and foundations need to be assessed to determine how the property can accommodate an additional level and whether structural modifications may be required.

This is why a property-specific assessment is more useful than relying on a generic online price.

For a more detailed look at the factors that influence pricing, read Sertorio Homes’ Second-Storey Addition Cost Guide.

What Affects the Cost of a Second-Storey Addition?

When researching second storey additions Perth cost, it is important to look beyond the size of the new floor. Several factors can influence the overall project cost.

1. The Size of the Second Storey

The amount of additional floor space is one of the most obvious factors.

A compact second storey may provide enough room for one or two bedrooms, while a larger addition could include multiple bedrooms, bathrooms, living areas, storage and other lifestyle spaces.

Generally, the more space you add, the more materials, labour and construction work will be required.

2. The Existing Structure

Adding another level places additional loads on your existing home.

The condition and construction of the house, along with its foundations and structural system, need to be considered during the planning stage.

Depending on the property, structural reinforcement or other modifications may be required before the new level can be constructed.

3. Design and Layout

The complexity of your design can also affect the cost.

A straightforward second-storey layout may have different construction requirements from a highly customised design featuring:

• Large windows
• Balconies
• Multiple bathrooms
• Open-plan living areas
• Complex roof structures
• Custom joinery
• Architectural features

Two homes with a similar amount of additional floor space can therefore have very different project costs.

4. Bathrooms and Plumbing

Adding a bathroom or ensuite upstairs introduces additional plumbing, waterproofing, fixtures and electrical requirements.

The location of the new bathroom can also affect how services connect with the existing home.

Planning these spaces early can help create a more practical and efficient design.

5. Stairs and Changes to the Existing Home

A new second storey needs a practical connection to the ground floor.

The position of the staircase needs to work with the existing floor plan while providing convenient access to the new level.

In some homes, creating space for the staircase may require changes to existing rooms or internal walls.

Sertorio Homes’ completed projects show how existing spaces can be adapted as part of a second-storey design. For example, the Carine second-storey addition incorporated an existing study to accommodate the staircase leading to the new upper-level spaces.

6. Materials and Finishes

Your choice of materials and finishes can also influence the final cost.

Flooring, windows, doors, cabinetry, bathroom fixtures, lighting and other finishes can range from practical and straightforward to highly customised.

Establishing your priorities early can help ensure the design reflects both your lifestyle and your budget.

Is Adding a Second Storey Better Than Moving?

For many homeowners, the decision isn’t simply about construction cost. It is about whether extending the home makes more sense than selling and moving.

Adding a second storey can allow you to:

• Stay in a neighbourhood you already enjoy
• Keep your existing backyard
• Create additional bedrooms
• Add a master suite or ensuite
• Create an upstairs living area
• Improve the functionality of your existing home
• Increase your living space without purchasing a larger property

Sertorio Homes has completed second-storey projects designed to create additional living space while retaining valuable outdoor areas.

The Rivervale second-storey project added three bedrooms, a bathroom, powder room, activity room and walk-in linen while allowing the homeowners to retain their backyard for future plans.

However, building upwards isn’t automatically the right choice for every property.

Your home’s condition, block, existing layout, budget and long-term plans should all be considered before deciding whether to extend or move.

Can You Add a Second Storey to an Existing House?

Many existing homes can potentially be extended upwards, but every property needs to be assessed individually.

The existing structure, foundations, roof design, floor plan, site conditions and proposed addition all need to be considered.

The new design should also work with the existing character and appearance of the home.

For example, the Swanbourne second-storey extension created a parents’ retreat, master bedroom, ensuite and walk-in robe while complementing the original character of the home.

This demonstrates why the design process is so important. A successful second-storey addition should feel like a natural extension of the existing property rather than simply another level placed on top.

What Is the Process for a Second-Storey Addition?

Understanding the process can help you prepare for your project and make better decisions about your budget.

1. Discuss Your Requirements

Start by identifying why you need more space and what you want the new level to achieve.

You may need additional bedrooms for a growing family, a larger master suite, an upstairs living area, a home office or additional bathrooms.

2. Assess Your Existing Home

The existing property needs to be assessed before the second-storey design is developed.

This helps identify potential structural, design and construction considerations early in the process.

3. Develop the Design

The new level can then be designed around your lifestyle, existing floor plan and available space.

The design should consider how the upstairs rooms connect with the ground floor and how the addition will work with the existing home.

4. Establish the Project Scope and Budget

Once the design direction is clear, the construction requirements and major cost considerations can be assessed.

This provides a more realistic basis for budgeting than relying on a generic price per square metre.

5. Work Through Approvals

Planning and building requirements can vary depending on the property and proposed development.

Sertorio Homes can assist homeowners through the relevant council approval process as part of its second-storey building approach.

Learn more about Sertorio Homes’ second-storey additions and the process involved.

6. Construction

Once the design, approvals and preparation are complete, construction can begin.

Depending on the project, this may include structural work, construction of the new level, roofing, plumbing, electrical work, internal fit-out and finishing.

How Can You Keep a Second-Storey Project Within Budget?

If you’re concerned about the cost to add a second storey, careful planning is important.

Start by identifying the spaces your household genuinely needs.

For example, if your primary goal is to create two additional bedrooms, adding unnecessary features could increase the project cost without providing meaningful value.

It can also help to establish your priorities before finalising the design. Decide which features are most important to your family and where you may be comfortable choosing a simpler solution.

Most importantly, consider the existing home early in the process. Understanding potential structural and design requirements before construction begins can help reduce unexpected changes later.

Because every home is different, Sertorio Homes does not rely on a standard price for every second-storey project. Instead, the design and construction approach can be considered around the individual property, requirements and budget.

If your family needs more space but you don’t want to give up your backyard or move away from your current neighbourhood, building upwards could be the solution you’ve been looking for.

From additional bedrooms and bathrooms to larger master suites and lifestyle spaces, a well-planned second storey can transform how your existing home works for your family.

Sertorio Homes has more than 40 years of experience creating homes and extensions throughout Perth, including second-storey additions designed around individual properties and lifestyles.

Explore Sertorio Homes’ Second Storey Additions in Perth to discover the options and process.

You can also view Sertorio Homes’ second-storey addition portfolio to see examples of completed projects across Perth.

Ready to Discuss Your Second-Storey Project?

If you’re considering adding a second storey to your Perth home, the best place to start is by understanding what is possible for your individual property.

Visit Sertorio Homes to learn more about the team, explore home and renovation services, and take the first step towards creating more space in the home you already love.

Thinking about building up rather than moving out? Get in touch with Sertorio Homes to discuss your second-storey project.