Home Extensions · Thornleigh NSW 2120
Home extensions in Thornleigh, done properly.
Rear and side house extensions for Thornleigh 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.
Start here
Tell us about your Thornleigh home.
No sales pitch, no obligation. Here is exactly what happens when you enquire:
- 1Answer a few quick questions. One at a time, takes about two minutes, so the first conversation is about your project rather than the basics.
- 2We call you within 24 to 48 business hours. A builder, not a salesperson. Then we walk your home and yard with you on site in Thornleigh.
- 3You receive a written, itemised estimate. Real numbers for your home. If the project does not stack up, we tell you that too.
From our clients
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.”
Extending out, not up
Thornleigh blocks have the room to extend.
Strava Group builds home extensions in Thornleigh: rear additions, side extensions and whole-of-back transformations that open the house to the garden. Thornleigh sits between Pennant Hills and Hornsby with post-war brick and weatherboard homes on generous blocks, newer homes on the former industrial land, and bushland running along the gullies toward the Lane Cove valley. There is almost always land at the back, and the original house rarely makes the most of it.
In Thornleigh 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.
Local knowledge
What we know about extending in Thornleigh.
Every suburb builds a little differently. This is what matters when you are extending a Thornleigh home.
Council
Thornleigh sits in the Hornsby Shire Council area under the Hornsby Local Environmental Plan 2013 and the Hornsby Development Control Plan. Most detached homes on standard residential zoning can pursue a ground floor extension through Complying Development with a private certifier rather than a full DA, subject to setbacks, site coverage and landscaped area. Heritage items and bushfire prone blocks toward the valley go to a DA. We confirm the pathway for your property before quoting. Current planning controls are published by Hornsby Shire Council and on the NSW Planning Portal.
Housing stock
A broad stock of 1950s to 70s brick veneer, full brick and weatherboard houses on the established streets, interwar homes near the station, and newer homes on the redeveloped land toward the Comenarra Parkway. Many have been extended once before, often with a family room or sunroom that was never built to last. Those earlier additions usually come off and are replaced with something engineered.
Structure
Brick veneer homes from the post-war decades are straightforward to extend once the load path is engineered. The older full brick houses need more care at the junction: we cut the openings cleanly, install engineered steel and tie the new frame into the existing brickwork properly. Weatherboard homes on brick piers extend well in timber, and the junction is where the flashing has to be done properly.
Yard and block
Blocks in Thornleigh are typically 650 to 950 square metres, many of them sloping toward the gullies and most of them treed. The trees are protected under council controls and sometimes shape where the extension can go. The size of the block means a substantial rear extension is usually possible while keeping a real garden, and on the steeper blocks the extension often steps down the site.
Services and ground
Thornleigh sits on shale derived clay over Hawkesbury sandstone, with the rock close to the surface on the slopes toward the valley. Footing design varies across a single 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. Bushfire construction requirements apply on the blocks backing the reserves.
Value
Thornleigh is a well connected shire suburb with the station, the schools and the bush setting holding demand. A well built extension that converts a dated rear layout into open plan living with a genuine garden connection is one of the most reliable improvements you can make here, and it usually costs less than the stamp duty and agent fees involved in moving to a bigger house nearby.
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 Thornleigh 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 Thornleigh 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 Thornleigh.
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.
Preliminaries are the costs that exist before a single wall moves: site fencing, temporary services, waste removal, insurances, engineering 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 Thornleigh the block sizes support a proper open plan rear rather than a single room, which tends to put projects in the middle of the band, with sloping sites and bushfire requirements on some blocks adding to it. How much of the existing structure has to change is usually the largest single factor, followed by wet areas and how far footings have to go to find rock.
Every project is quoted properly after a site inspection. These ranges are here so you can decide whether it is worth a conversation.
Nearby We build extensions across Hornsby Shire and the surrounding suburbs. Select a suburb for local council information and what extensions there typically cost. Looking for a different service in Thornleigh? We also build second storey additions and home renovations.
Home extensions near Thornleigh.
Hornsby Shire
Good to know
Thornleigh extension questions.
How much does a home extension cost in Thornleigh?
Do I need council approval for an extension in Thornleigh?
How long does a home extension take to build in Thornleigh?
Can I live at home during the extension?
Should I extend out or add a second storey in Thornleigh?
Will the extension match my existing house?
How will I know what is happening during my extension?
Are you licensed and insured?
Extend your Thornleigh home properly.
Ready for more room?
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.
