Home Extensions · Chatswood NSW 2067
Home extensions in Chatswood, done properly.
Rear and side house extensions for Chatswood homes by a licensed extension builder. Most extensions run $70,000 to $300,000 depending on size and how much of the existing house has to change, itemised quote, honest programme, one builder from concept to handover.
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Extending out, not up
Extending a Chatswood home on a valuable block.
Strava Group builds home extensions in Chatswood: rear additions, side extensions and whole-of-back transformations that open the house to the garden. Chatswood land is expensive, which changes the maths: every square metre you add is worth more here than almost anywhere else we build, and moving to a bigger house nearby costs a great deal in stamp duty and agent fees. The detached streets west and east of the centre are full of Federation, interwar and mid-century homes with room at the back to grow.
In Chatswood we regularly deliver:
- Rear extensions and additions
- Side extensions on wider blocks
- Open plan kitchen, dining and living
- Alfresco and indoor-outdoor connections
- New master suites and family rooms
- Laundries, mudrooms and storage done properly
- Structural openings between old and new
- Exterior upgrades to tie old and new together
Thinking about going up instead? That is a different build with different engineering, and we do that too: see second storey additions in Chatswood.
In Chatswood the question is rarely whether an extension adds value. It is how to add the space without giving up the garden, and how to make the new rear feel like it was always part of the house.
Quick Answer
Most home extensions in Chatswood run $70,000 to $300,000 depending on size and how much of the existing structure has to change, at roughly $2,500 to $4,500 per square metre for ground floor work, with around $30,000 in preliminaries (design, engineering and council approvals, plus site set-up) on top. The value of the land here tends to justify extensions toward the upper end of the band, and heritage controls and sloping sites add design and engineering work.
Local knowledge
What we know about extending in Chatswood.
Every suburb builds a little differently. This is what matters when you are extending a Chatswood home.
Council
Chatswood sits in the Willoughby City Council area under the Willoughby Local Environmental Plan 2012 and the Willoughby Development Control Plan. Several residential precincts, particularly toward Chatswood West and Roseville, sit inside heritage conservation areas where extensions go through a Development Application. Outside those areas many detached homes can use Complying Development through a private certifier. We confirm the pathway for your property before quoting. Current planning controls are published by Willoughby City Council and on the NSW Planning Portal.
Housing stock
Federation and Californian bungalows on the older streets, interwar brick homes, and a good stock of 1950s and 60s houses further out, with high density concentrated around the station and the Pacific Highway. The detached homes often have small rear kitchens and a sunroom or lean-to added decades ago. Those earlier additions usually come off and are replaced with something engineered.
Structure
Older Chatswood homes are double brick or brick veneer on timber floors with hardwood framing and terracotta roofs. Cutting a new opening into a double brick rear wall needs an engineered lintel and careful propping, and matching the new floor to the existing suspended floor level is a detail that has to be right. Mid-century brick veneer homes extend more simply once the load path is engineered.
Yard and block
Blocks are typically 550 to 800 square metres, with the streets toward Lane Cove River often larger and sloping. Side access varies, and on the tighter blocks materials may have to come through the house. A rear extension that keeps a usable garden, often with a covered outdoor room, is the usual brief.
Services and ground
Much of Chatswood sits on shale derived clay with Hawkesbury sandstone close to the surface on the slopes toward the river. Footing design varies across the suburb and sometimes across one block, so the engineering is done for your site, and new footings are detailed against the existing ones so the extension does not settle away from the house. Services along the rear boundary are located before design starts.
Value
Chatswood is one of the highest value detached housing markets we work in, with the rail and Metro interchange, Westfield and Chatswood Chase, and strong school catchments holding demand. A properly built extension that turns a dated rear into open plan living with a garden connection is worth a great deal here, and it is almost always cheaper than buying the bigger house down the street.
Start here
Tell us about your Chatswood home.
No sales pitch, no obligation. Here is exactly what happens when you enquire:
One at a time, takes about two minutes, so the first conversation is about your project rather than the basics.
The Strava standard
How we build differently.
An extension lives or dies at the junction between old and new. We build for longevity, and on every Chatswood extension we run:
Every new-to-existing junction properly detailed
This is where most extensions crack, leak and part company with the house. It is almost always a detailing shortcut, not settlement. Ours get a proper structural tie, flashing and movement detail.
The existing structure gets rectified, not covered
Where the extension meets the house, we screw off and re-brace the adjoining structure, tying new and old together so the whole building moves as one and future cracking is designed out, not painted over.
Footings matched to the ground, not the minimum
New footings are engineered for your soil and detailed against the existing ones, because differential movement between old and new slabs is the classic extension failure, and the mix of clay and shallow sandstone across Chatswood means the engineering is done for your site, not copied from a neighbour.
Furring channels for a dead flat finish
Where new ceilings and walls run through to existing rooms, furring channels give one level plane across both, so you cannot see where the house ends and the extension begins.
Waterproofing is a documented hold point
New wet areas are inspected and photographed before a single tile goes on, to AS 3740, and new roof-to-old-roof junctions get the same treatment.
Everything photographed before it is covered
You receive the record at handover, so in ten years you know exactly what is behind your walls and under your floor.
Before starting Strava Group, I spent seven years on the tools as a carpenter and five years running sites. The failures I kept seeing in extensions were always at the join: cracked cornices along the old wall line, roofs that leaked where new met old, floors that stepped as slabs settled differently. None of it was illegal. All of it was avoidable. None of this shows up in a finished-room photo. All of it shows up in year seven.
Honest numbers
What a house extension actually costs in Chatswood.
Most builders will not put numbers on a website. We will, because the alternative is wasting your time and ours across three meetings before anyone mentions a figure.
| Item | Typical range |
|---|---|
| Home extension, depending on size and scope | $70k–$300k |
| Ground floor extension work | $2,500–$4,500 /m² |
| Preliminaries, on top of build cost | approx. $30,000 |
Preliminaries are the costs that exist before a single wall moves: design, engineering and council approvals, plus site set-up such as site fencing, temporary services, waste removal, insurances and supervision. They are real, they are unavoidable, and a quote that does not show them separately has either buried them or forgotten them.
In Chatswood the value of the land tends to justify extensions at the upper end of the band, with heritage controls on some streets and sloping sandstone sites adding design and engineering work. How much of the existing structure has to change is usually the largest single factor, followed by wet areas, site access and how far the new footings have to go.
Every project is quoted properly after a site inspection. These ranges are here so you can decide whether it is worth a conversation.
Good to know
Chatswood extension questions.
Rated 5.0 on Google.
We had Strava Group complete major renovation works on our property and were blown away with the quality. The attention to detail and overall finish were amazing.
Great communication, honest work, easy to work with, highly recommend to work with for any new build/renovations. If you are looking to get work done without worrying about shortcuts Strava Group is builder to use.
I highly recommend Strava Group to everyone great workmanship, reliable service, and I couldn’t be happier with the result.
I couldn't be happier with the work from Strava Group. From the beginning, Stav and the team was friendly, honest, and super easy to deal with.
We engaged Strava Group for a home extension and renovation. We are incredibly happy with the service and the results we achieved. From day one Stav and team where always willing to help with any issues we had and we loved that the main focus was as quality and longevity. Highly recommended
Had a great experience with Strava Group. The team was easy to deal with, super professional, and kept me in the loop the whole way through. They really listened to what I wanted and made the whole process feel smooth and stress-free.
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Nearby
Home extensions near Chatswood.
We build extensions across the lower North Shore and the Ryde district. Select a suburb for local council information and what extensions there typically cost.
North Shore and Ryde district
The Hills District
Hornsby and the Northern Suburbs
Ryde, Hunters Hill and the North Shore
Inner West
Parramatta
Western Sydney
Southern Sydney and St George
Looking for a different service in Chatswood? We also build second storey additions in Chatswood and home renovations in Chatswood.
Extend your Chatswood home properly.
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Tell us about your property and what you want to add. We respond within 24 to 48 business hours with honest advice and real numbers, no cost, no obligation.
More in Chatswood
Other Strava Group services in Chatswood
Each page covers the local council, the homes we see in Chatswood and what that kind of project typically costs.