Home Extensions · Seven Hills NSW 2147
Home extensions in Seven Hills, done properly.
Home extensions in Seven Hills by a licensed builder, for the post-war timber cottages and older homes found across the suburb. 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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Building onto a post-war cottage
Extending a Seven Hills cottage.
Strava Group builds house extensions in Seven Hills: new kitchens and family rooms across the back, extra bedrooms, a second bathroom and covered decks. The Housing Commission started building here in 1945, and much of the suburb is timber framed cottages from that period onward. A timber frame extends well, provided the subfloor, the old cladding and any earlier additions are dealt with first.
Extensions we build for Seven Hills homes:
- Rear living and kitchen extensions
- Extra bedrooms and second bathrooms
- Recladding the house with the extension
- Replacing old rear additions
- Subfloor levelling at the join
- Extensions designed to flood floor levels
- Covered decks and outdoor rooms
- Insulation upgrades through the old walls
If the cottage already has the room it needs, our page on home renovations in Seven Hills covers bringing the inside up to date. For space while keeping the yard, second storey additions are possible on a sound frame, which we check first.
A post-war Seven Hills cottage takes an extension well. Open the timber frame at the back, add the living space on matching floor levels, then reclad the whole house so nobody can tell where the original stops.
Quick Answer
Most home extensions in Seven Hills 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. Asbestos removal, recladding the house with the extension and subfloor repairs at the join add the most to a Seven Hills quote.
Local knowledge
What we know about extending in Seven Hills.
Most Seven Hills extensions are added to older timber homes, which brings a few jobs of its own. Here is what we deal with.
Council
Seven Hills is entirely within Blacktown City Council under the Blacktown LEP 2015. A private certifier can sign off many single storey additions under Complying Development, while a lot with flood controls or other site constraints may need a DA. Controls are on the Blacktown City Council website and the NSW Planning Portal.
Housing Commission cottages
Much of the suburb was built by the Housing Commission from 1945 as timber framed cottages. Those frames are straightforward to open up, and where a cottage sits on piers we check the bearers, joists and wall plates at the junction for rot and termite damage before connecting anything.
Fibro and asbestos
Fibro cladding or linings on a cottage of this era may contain asbestos. We sample anything suspect before a saw goes near it. If the lab confirms asbestos, a licensed removalist takes it out under controlled conditions and you get the clearance paperwork, with the cost shown in the quote.
Flood controls
Some Seven Hills lots carry flood planning controls. They sit in the Blacktown LEP flood clauses, council flood studies and the DCP, with no LEP map layer to look them up on, so the planning certificate for your lot is the place to check. Where controls apply, they set how high the new floor must be.
Recladding
Because the extension needs new cladding anyway, many owners reclad the whole house at the same time. Fibro or tired weatherboards come off, insulation and sarking go in, and new cladding wraps old and new as one building.
A typical extension
A rear addition of 25 to 40 square metres: kitchen, dining and family room opening to a deck, often with a second bathroom and laundry beside them. The old back rooms become bedrooms or a study.
Start here
Tell us about your Seven Hills 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 Seven Hills extension we run:
Every new-to-existing junction properly detailed
This is where most extensions crack, leak and part company with the house, and the cause is almost always a detailing shortcut. Ours get a proper structural tie, flashing and movement detail.
The existing structure gets rectified first
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. Future cracking gets designed out at frame stage instead of patched at the paint stage.
Footings engineered for the ground they sit on
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 it matters more on an older house whose original footings were never engineered to modern standards.
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. Want more than photos? We can also capture a full 3D virtual model of the frame, plumbing, wiring and waterproofing before the plasterboard goes on, available as an optional add-on.
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 Seven Hills.
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 Seven Hills, asbestos testing and removal, repairs at the junction and recladding tend to put projects in the lower to middle part of the band, with flood floor levels adding on affected lots. Beyond those, the final figure rests on the number of wet areas and how much of the existing structure has to change.
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
Seven Hills extension questions.
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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 Seven Hills.
We build extensions across Blacktown and the surrounding suburbs. Select a suburb for local council information and what extensions there typically cost.
Blacktown and surrounds
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 Seven Hills? We also build second storey additions and home renovations in Seven Hills.
Extend your Seven Hills 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 Seven Hills
Other Strava Group services in Seven Hills
Each page covers the local council, the homes we see in Seven Hills and what that kind of project typically costs.