How Much Does a House Extension Cost

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Costs Breakdown – Sydney House Extension


When you could sell your house and move to a larger home, why would you accept a house extension? Here are three good reasons to consider adding a house extension in Sydney.

  • You are not obligated to relocate if you enjoy your current place.
  • Make the improvements you want to make rather than settling for something mediocre.
  • Moving to a larger home may be more expensive than extending your home.
  • You may be emotionally attached to your current residence or place and unable to leave.

As a general rule of thumb, a 50SQM ground floor house extension in Sydney costs between $255,000 and $350,000. This equates to $4,500m2 – $6,000m2 (Single storey extension). Bathrooms, kitchens, architectural fees, consent fees, GST, and structural engineer fees are not included. GET costs for ground-level house extension in Sydney HERE


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To Sum It All Up

What Is the Cost of Extending a House per Square Metre?

The cost per square metre to expand a house ranges from $3,000 to $4,500, depending on the complexity and scope of work.

What Does It Cost to Build a Second Storey to a House?

As compared to a normal one-storey extension, adding a second storey to a house will cost 43 percent to 66 percent more.

Is a Building Permit Needed for a Home Addition?

Building permission is needed for a house extension because structural changes would be made as well as a change in footprint. In house extensions, you can consult with an architect and a structural engineer.

The cost of renovating your home’s exterior ranges from $34,900 to $258,152+.

When Building a House Extension, How Do You save Money on the Interior Finish?

The final step in your renovation project is to finish the walls, ceiling, and flooring in your new room. If money is tight, go for a high-quality neutral finish. Later on, you can still add personal touches and upgrades. Wooden laminates or vinyl floors are a cost-effective and attractive choice for flooring.

For a House Extension, Prices for Labour Cost and Other Inclusions Must Also Be Considered.

A well-defined plan can assist you in determining project details as well as the estimated cost of each component needed for house extensions.

Expect to pay more for expansion projects that necessitate foundation work, infrastructure evaluation, and significant structural changes. To insure the standard of the building, find a home extension builder who will work in a timely and professional manner.

Make sure the design specifications are finalised before the actual work begins. The aim of the initial consultation is to properly set out your costings.

Labor Costs for a House Extension

Most home extension contractors hire electricians, plumbers, and carpenters to complete the work. They work with tradespeople to expedite the process and make the room habitable.

To give you an idea of how tradies charge, here are their average hourly rates (Note: Prices are inclusive of overheads and profits).

  1. Electrician rates range from $69 to $135 per hour.
  2. Plumbers charge between $74 and $129 per hour.
  3. Bricklayers earn between $79 and $108 per hour.
  4. Carpenters and joiners earn between $78 and $109 per hour.
  5. $58 – $109 per hour for a painter or glazier
  6. $35–$55 per hour for a tiler


House Extension Costs in 2021

Although there are several factors that can influence the cost of an extension in Sydney in 2021, the most significant consideration is the extension’s duration. This is because the project’s scale (which is usually measured in square feet) is directly proportional to the overall expense.


In Sydney, a single-storey extension costs between $2,800 and $3,600 per square metre ($285 and $380 per square foot). Finishes and goods that cost $4,000 per sqm will be considered cost-effective. You should expect to pay between $2,400 and $2,500 per square metre ($110 and $140 per square foot) elsewhere throughout NSW, Australia.


Add 50 to 60% to the guideline price of a single storey extension to get a rough estimate of the cost of a two-story extension. Two-story extensions save money since only one set of foundations is required, for example. Two-story extensions can be more difficult to obtain zoning approval for.

Cellar or Basement Space

A basement is more expensive due to the difficulty and risk of building. In Sydney, a basement extension costs between $6,000 and $7,000 per square metre ($370 and $465 per square foot).

What Is the Purpose of the Extension?

Many people plan to extend their homes to include a kitchen or a bathroom. When opposed to additional bedrooms or living spaces, this would inevitably boost the total cost.


If you want to include a kitchen in your expansion, plan on spending an extra $25,000 to $65,000. A low to mid-range design, complete with units and some appliances, would normally cost $18,000.


The expense of adding a bathroom will range between $12,000 to $18,000. The cost will rise as the standard of the fixtures and fittings improves.

Fees for a House Extension Consultant

An Architect

Architects are often the first point of touch for a project, and they are a wise investment. They’ll take care of the important aspects of the project, such as design and obtaining planning approval.
Perhaps most significantly, an architect aids in the transformation of a concept into reality. They produce the detailed plans needed by builders in order for them to provide accurate quotes.

Alternative options that are more cost-effective and help minimise costs can also be provided by an architect. Reorganizing and upgrading existing spaces may often be less expensive and more beneficial than a poorly planned home addition.

Various Other Consultants

Depending on the scope of the project, additional specialist consultants will be needed. When these are necessary, an architect will discuss and determine when they are needed. Quantity surveyors and engineers are common examples of specialist consultants.


House Extensions Sydney Don’t Overpay

Additional Expenses


Once plans have been established and a Council fee quotation has been given, CDC or DA/CC fees will be advised. The lodgement training for either CDC or DA/CC begins at $7,500. This is where we obtain any additional relevant documentation required for your build to be ready to begin, such as;

  • Engineering plans and, if a first-floor addition is being built, a first-floor certification are needed to insure that your current home can accommodate the addition.
  • Check with Sydney Water to insure that your construction would not negatively affect any of Sydney Water’s properties.
  • We get a sewer service diagram so the plumber can see where the current connections to the house are.
  • Long Service Levy – This levy is applied to all residential projects that cost more than $20,000.
  • Home Warranty Insurance – Covers all residential work over $20K, as well as any other documentation required.

Costs of Large Items

Doors and windows

Windows are costly; in general, the larger the window, the higher the cost per square metre of the unit. The amount of glazing you want, the amount of insulation you want, and the style and fitting of the window would all affect the price of the window.

Doors are an additional cost, particularly if you want wide sliding patio doors or bi-folding doors, for example. However, the amount of light in your home can greatly enhance the enjoyment of it, and the opportunity to open up living spaces to gardens can drastically improve how spaces are used during the summer months.



Thermostatically regulated heating & cooling

Your boiler and central heating system could not be able to cope with the extra rooms and space depending on the scale of your extension. To accommodate the extra room, you may need to upgrade your system or add a second heating system to the house.

Restrictions on the site

If there are any problems with the extension’s location, the cost would almost certainly rise. For example, the soil type can necessitate the use of more expensive building materials.
If your home is difficult to reach, such as a terraced building, the builders can charge an additional fee to cover the cost of gaining access for staff, materials, and equipment.

Trees, drainage, pipework, steel work, gas metres, sheds, conservatories, and fuse boxes can all need to be moved, which will add to your extension costs. If you’re working on a listed building or a house in a protected area, you’ll need to budget more for consultants and construction.

To Discuss Your Home Addition Idea, Contact Us 

Please use the contact form on this page to provide us with your contact information if you’d like to explore options and ideas for your extension project. We will contact you at a time that is convenient for you to discuss your project. If you’d like to give us more details about your idea, we also have a more detailed enquiry form on our “Get in touch” tab.



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Canterbury Bankstown Council Two Storey Extension Cost

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Builders Sydney Experts
Level 1 , 169 Castlereagh St
Sydney, NSW 2000
Phone: 0490842094
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