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How to convert single storey extension to double storey extension?

5 December 2023

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To convert a single-storey extension into a double-storey extension, you will need to assess the structural feasibility of your existing home and plan the extension project accordingly. This involves consulting with professionals, obtaining necessary building permits, reinforcing or replacing the foundation if needed, modifying load-bearing walls, extending plumbing and electrical systems, constructing the second level, and ensuring compliance with building codes. The process requires careful design considerations and expert guidance to smoothly integrate the additional floor into your existing home.


What are the things to consider when adding a second-storey extension?

Converting a single-storey home into a double-storey home typically involves an extensive renovation process that can vary depending on the specific requirements of the project and local building regulations. Here is a general outline of the steps involved:

  1. Consult with an Architect or Structural Engineer: Engage the services of Experienced home builders, professional architects, and structural engineers in residential design and construction. They will assess the feasibility of converting your single-story extension into a double-story extension and help you develop a suitable design plan.
  2. Obtain necessary permits: Check with your local building authority to determine the permits and approvals required for the extension. Your Home builder/ contractor or team of architects from Dhursan Construction will guide you through the hassle-free permit application process.
  3. Structural considerations: The existing single-storey extension will need to be assessed for its ability to support an additional story. The structural engineer will evaluate the foundation, walls, and roof to ensure they can handle the increased load.
  4. Design modifications: Work with your architect to modify the existing single-story design to accommodate the additional floor. This may involve changes to the foundation, load-bearing walls, and roof structure.
  5. Foundation and structural work: If the existing foundation is not suitable to support an additional floor, it may need to be reinforced or replaced. The load-bearing walls may require modifications to support the new structure. The roof may also need to be altered to accommodate the increased height.
  6. Extension construction: Once the necessary structural modifications are complete, the construction of the additional floor can begin. This typically involves erecting new walls, installing flooring systems, and constructing the roof.
  7. Plumbing, electrical, and HVAC systems: Extend the necessary plumbing, electrical, and HVAC (heating, ventilation, and air conditioning) systems to the new floor. This may involve hiring licensed professionals to ensure compliance with building codes.
  8. Insulation and soundproofing: Install appropriate insulation and soundproofing materials in the walls, floors, and ceilings to improve energy efficiency and minimise noise transmission between floors.
  9. Interior finishing: Complete the interior finishing work, including installing drywall, flooring, doors, and windows. Follow your design plan to create the desired layout and aesthetics, or Collaborate with Dhursan Constructions for the design!
  10. Exterior finishing: Finish the exterior of the extension to match the existing structure. This may involve matching the siding, roofing, and architectural details. View our elegant Home designs and experience a style that will transcend your expectations!
  11. Safety and compliance: Ensure that the new second-storey extension meets all safety and building code requirements. This may involve inspections by local authorities at various stages of construction.


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Let’s look at the main factors that should be considered when you truly plan to add a second-storey extension:

Access and Staircase Design:

Determine the best location for the staircase that will connect the existing floor with the new level. Carefully consider the design, size, and placement of the stairs to optimise traffic flow and ensure ease of use.

The type of staircase chosen will depend on various factors, including personal preference, architectural style, and available space. Options such as straight, L-shaped, U-shaped, or spiral stairs can be considered, each offering unique advantages and considerations. Depending on the design and location, there may be a need for structural modifications, such as reinforcing walls or installing additional supports. The design should meet building codes and regulations, ensuring proper dimensions, handrail placement, and tread and riser measurements for comfortable and safe use.

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Natural Light and Views:

When working with an existing building, evaluate the placement and size of windows. If feasible, you may consider enlarging or repositioning windows to enhance the amount of natural light and improve views. It’s also worth considering the removal of any obstructions, such as overgrown trees or shrubs that may block light or obstruct desirable views.

To increase natural light, it’s crucial to incorporate large windows and glass doors strategically throughout the house. This allows ample sunlight to enter the space, creating a bright and inviting atmosphere. Additionally, consider the orientation of the windows to optimise the amount of sunlight received during different times of the day. Incorporating skylights or light wells can also be an effective way to introduce natural light into areas that are otherwise difficult to illuminate. These architectural features bring light from above, creating a sense of openness and connection to the sky.

Two Storey Extension Budget and Timeline:

Establish a realistic budget for the project and create a timeline that encompasses the various stages, including design, permits, construction, and finishing. The timeline for a two-storey extension project can also vary based on factors such as the size and complexity of the extension, site conditions, and any unforeseen challenges that may arise during construction. It is essential to work closely with your builder to establish a realistic timeline and ensure timely completion of the project.

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Second-storey addition in Sydney: Estimated Cost in 2024

In Sydney, NSW, the cost of a second-storey addition typically starts at $300k. However, if you are also extending your ground floor simultaneously, the cost can range from $350k to $600k and even higher. The final price will depend on various factors, such as the size of the extension, the complexity of the design, the number of rooms, floor extension, chosen building materials, additional features, and the overall scope of the building. Typically, the cost of a two storey extension is calculated per square metre, taking considerations into account like- labour, materials, permits, and other related expenses. It is recommended to consult with reputable home builders and Obtain detailed quotes to create an accurate budget.

Double Storey Extension Design Ideas

When considering double-story extension design ideas, it’s important to maximise the functionality and aesthetics of both the ground floor and first floor. The ground floor can be utilised for various purposes, such as expanding the living space, adding a bedroom, or creating a larger living area. Additionally, incorporating a new bathroom on the ground level can enhance convenience and accessibility.

The staircase is a crucial element in a second-storey extension, connecting the ground floor and first floor seamlessly. Careful attention should be paid to its design, ensuring it complements the overall style of the extension while providing safe and easy access between the floors. On the first floor, the additional space can be utilised for various purposes, such as creating additional bedrooms, a master suite, or a dedicated home office. This floor addition opens up possibilities for enhancing privacy and optimising the use of space.

Overall, a well-designed second storey extension can transform your home, providing ample living space and offering a seamless blend of functionality and aesthetics across both the ground and first floors. One of the major advantages of a two storey extension is the potential increase in the value of your home. By expanding the living space and adding more functional areas, you not only enhance your family’s lifestyle but also improve the market value of your property.

Discover a plethora of captivating Home designs awaiting your exploration!

Build a second storey addition with a Reputed Home Builder in Sydney!

Experience craftsmanship at its finest by partnering with a reputable home builder in Sydney to construct your second storey addition. Our expert team of builders at Dhursan Construction is dedicated to crafting exceptional homes with exceptional attention to detail.

Customers are at the heart of everything we do. We understand that embarking on a second storey addition as a homeowner is a significant investment and an important milestone for our customers. That’s why we prioritise customer satisfaction and go the extra mile to ensure their needs are met. From the initial design phase to the final touches, we work closely with you to bring your vision to life. Trust us to deliver a high-quality, well-executed project that exceeds your expectations.

Contact Us today to embark on your journey towards a stunning second storey addition!

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