How Much Does a Home Extension Cost on the Central Coast?
If you’ve outgrown your home but love where you live, a home extension could be the perfect solution. But the big question is: how much will it actually cost to extend your home on the Central Coast?
The answer depends on several factors, including the size of the extension, the scope of work, the complexity of your block, and the level of finishes you choose. Below, we break down what to expect—and how to budget smartly.
👉From 1970s Cottage to Contemporary 4-Bedroom Family Home. A Completed Home Extension By Hemmens Building
Average Cost of a Home Extension in Central Coast NSW
While every project is unique, here’s a rough guide to extension costs in the region:
| Type of Extension | Estimated Cost Range |
|---|---|
| Ground Floor Extension | $2,800 – $4,000 per m² |
| Second Storey Addition | $3,200 – $4,500+ per m² |
| Full Home Renovation + Extension | From $300,000+ |
👉 For a typical 50m² rear extension with open-plan kitchen and living: expect $200,000–$250,000+
What Affects the Cost?
1. Size & Scope
A larger footprint or adding a second storey means more structural work, more materials, and more labour.
2. Site Conditions
Sloping blocks, access limitations, or excavation needs can increase build costs.
3. Inclusions & Finishes
Upmarket finishes, custom joinery, high ceilings, and larger windows all add to the final figure.
4. Services Upgrades
Older homes may need electrical or plumbing upgrades to meet current codes.
5. Council & Approvals
DA approval, surveys, and consultant reports can add ~$15K–$30K before building even starts.
6. Functionality & Room Types
When estimating based on square metre rates, it's important to consider what is being included in the extension. For example, a 50m² extension that includes a kitchen remodel, bathroom, and living space will be significantly more expensive per square metre than a 50m² extension that simply adds a bedroom and lounge. High-spec areas like kitchens and bathrooms require more trades, fixtures, and services—dramatically increasing costs compared to simpler spaces.
Tips to Keep Your Extension on Budget
Involve your builder early – Get a preliminary estimate before completing final plans
Be clear on your priorities – Know where to spend and where to save
Allow for contingencies – Keep a buffer (5–10%) for unknowns like weather or site surprises
Avoid changes during construction – Variations are the #1 budget killer
Why Build with Hemmens?
At Hemmens Building, we help families across the Central Coast expand and improve their homes—without the budget blowout.
✔ Transparent pricing and realistic allowances
✔ Advice on where to save vs spend
✔ Full design-and-build guidance or build-only services
✔ Projects completed in Buff Point, Bateau Bay, Terrigal and more
Thinking About an Extension?
Before you commit to final drawings, book a no-obligation consultation with us. We’ll give you clarity on what’s possible—and what it will really cost.
Bonus FAQ
Most smaller-scale extensions take around 4–6 months from site start to completion. Larger, more complex renovations and extensions can take 12 months or longer, depending on the scope of work and weather conditions.
Usually yes, especially for ground floor rear extensions. We plan to minimise disruption.
