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Second Storey Additions St Marys – More Space for Your Growing Home

With over 20+ years’ experience in Sydney’s north-west, we transform homes to complement our client’s lifestyles and budgets.

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Keystone Building is a trusted local builder specialising in second-storey additions in St Marys and Western Sydney. For over 20 years, our family-run team has been designing and building smart extensions that help families create more space without needing to move. Whether you need an extra bedroom, a larger living area, or a new bathroom, we deliver high-quality results on time and within budget.

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Who We Are

We provide a full-service approach: from design, drafting, and engineering through to council approvals and construction. Our fixed-price contracts and clear timelines give you peace of mind, and most clients remain in their homes during the build.

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Preserve Outdoor Space

Build vertically to maintain your backyard, garden, or pool area— ideal for smaller blocks.

Add Views and Light

Second levels can open up elevated outlooks and bring in more sunlight, enhancing both value and lifestyle.

Get More Privacy

Create spacious master suites or quiet study areas completely separated from the main living zone.

Boost Property Value

Second storey additions are a strong investment, often delivering a higher return by substantially increasing usable floor area.

Why Us?

At Keystone Building, families choose us because:

We are local building experts with over 20 years of experience in Western Sydney
We specialise in second-storey home additions and complex structural work
We offer fixed pricing and clear build schedules
You can often stay in your home during the build
We provide end-to-end project management, handling everything from approvals to final handover

Learn more about our approach on our Why Choose Us page.

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How We Can Help

If you're looking at a second-storey addition in St Mary's, Keystone Building can offer:

Free first consultation and quote
Fixed price contracts with timelines
Project management from design to completion
Access to trusted suppliers like Beaumont Tiles and James Hardie
Skilled trades with a good reputation

Our goal is to make the process smooth, transparent, and stress-free while delivering the extra space your family needs.

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Maximise Your Home with a Second Storey Addition

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Families in St Marys looking to create more room without relocating can turn to Keystone Building for expert second storey additions. Adding an extra level provides additional bedrooms, bathrooms, or living areas while preserving your existing yard and outdoor space. This approach not only enhances your lifestyle but also increases your property value, making it a smart long-term investment.

Our experienced team manages every aspect of the build, from structural planning and council approvals to construction and finishing touches. With Keystone Building, your second storey addition will seamlessly blend with your home’s current design, delivering functional and stylish spaces that cater to your family’s needs.

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Facts About Us

Essential Facts About Second Storey Additions

Building up instead of out is often the best choice for growing families in St Marys. With land sizes limited and the cost of moving increasing, a first-floor addition can transform your home without leaving your neighbourhood.

Here's what makes second-storey extensions practical and valuable:

More living space – Create extra bedrooms, bathrooms, or a retreat upstairs while keeping your backyard untouched.
Increase property value – Homes with double-storey additions in St Mary's often achieve higher resale prices.
Custom layouts – From a parent's retreat to a teen space or a home office, second levels can be designed for your lifestyle.
Stay in your home – Most of our projects allow families to remain living on-site while work is underway.
Structural expertise – Adding another level requires knowledge of foundations, roof removal, and weight-bearing walls. Our team has over 20 years of experience delivering these builds.
Council approvals handled – We manage all engineering and council requirements, so the process is straightforward.
Cost-effective solution – A second-storey addition in St Marys, NSW can often be more affordable than buying a bigger house and paying stamp duty.
Upgrades are available for kitchens, bathrooms, decking, and outdoor spaces within the same project.
Minimal disruption – Our trades are respectful, clean, and mindful of the fact that you're living in your home during construction.
Local knowledge – Being based in Western Sydney, we're familiar with the planning rules of Penrith and St Marys councils.

With Keystone, you get more than just extra space; you get a practical, well-managed build designed for long-term comfort and convenience.

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Custom Designs for Every St Marys Home

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No two families are alike, which is why Keystone Building offers tailored second storey additions to suit your lifestyle. Whether you need a master suite retreat, a kids’ play area, or an expanded living space, we design solutions that meet your requirements while complementing the character of your home.

We focus on maximizing space efficiency and aesthetic appeal, ensuring that each addition feels like a natural extension of your property. Our team in St Marys works closely with you during the design process, making sure your vision becomes a reality without unnecessary stress or delays.

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About Us

Trusted Local Builders for Peace of Mind

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When adding a second storey, it’s essential to work with builders who understand local regulations and construction challenges. Keystone Building brings years of experience to St Marys projects, ensuring your addition is structurally sound and compliant with council requirements.

From start to finish, we prioritise communication, reliability, and craftsmanship. Our commitment to quality and attention to detail ensures that your second storey addition not only provides extra space but also enhances your home’s style and functionality. With Keystone Building, you can enjoy peace of mind knowing your project is in expert hands.

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