Home Extensions · Castle Hill NSW 2154
Home extensions in Castle Hill, done properly.
Rear and side house extensions for Castle Hill 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 Castle Hill 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 Castle Hill.
- 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
Castle Hill blocks were made for extending.
Strava Group builds home extensions in Castle Hill: rear additions, side extensions and whole-of-back transformations that open the house to the yard. Castle Hill is one of the best suburbs in Sydney for extending out. The blocks from the 1970s, 80s and 90s subdivisions are typically generous, the houses often sit well forward on them, and there is usually land at the back that a well planned extension can put to work.
In Castle Hill 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 Castle Hill.
Local knowledge
What we know about extending in Castle Hill.
Every suburb builds a little differently. This is what matters when you are extending a Castle Hill home.
Council
Castle Hill sits in The Hills Shire Council area under The Hills Local Environmental Plan 2019 and the Hills 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. We confirm the pathway for your property before quoting. Current planning controls are published by Hills Shire Council and on the NSW Planning Portal.
Housing stock
Mostly brick veneer and full brick single storey homes from the 1970s through the 1990s, plus newer two storey project homes on the later estates. The older homes usually have compact kitchens at the rear, separate dining rooms and a back door onto a concrete patio. That is exactly the layout an extension is designed to fix.
Structure
Brick veneer homes of this era are straightforward to extend, with timber framed walls and trussed roofs that take a new structural opening well once the load path is engineered. Full brick homes need more care at the junction: we cut the openings cleanly, install engineered steel and tie the new frame into the existing brickwork properly.
Yard and block
Standard Castle Hill blocks from the main subdivision eras are typically 700 to 1,000 square metres, which leaves room for a substantial rear extension while keeping a real backyard. The newer estates are tighter, so side and rear setbacks drive the design more. Sloping blocks around the creek lines need the footing design to be taken seriously, which is where the next card comes in.
Services and ground
Much of the Hills sits on shale and clay derived soils, which move with moisture. New footings on an extension have to be engineered for the site class, not copied from the original house, and detailed against the existing slab or strip footings so the two do not settle at different rates. Sewer lines often run along the rear of Castle Hill blocks, so we locate them early and design around them.
Value
Castle Hill is an established family suburb with the Metro, Castle Towers and school catchments holding demand. A well built extension that converts a dated rear layout into open plan living with a genuine yard connection is one of the most reliable improvements you can make to a home 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 Castle Hill 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 Hills clay soils make it more likely, not less.
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 Castle Hill.
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 Castle Hill the larger blocks tend to push projects toward the middle and upper part of the band, because there is room to build a proper open plan rear rather than a single room. How much of the existing structure has to change is usually the largest single factor, followed by wet areas, sloping sites and how far the new footings have to go to find good ground.
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 the Hills and the surrounding northern suburbs. Select a suburb for local council information and what extensions there typically cost. Looking for a different service in Castle Hill? We also build second storey additions in Castle Hill and home renovations in Castle Hill.
Home extensions near Castle Hill.
The Hills and surrounds
Good to know
Castle Hill extension questions.
How much does a home extension cost in Castle Hill?
Do I need council approval for an extension in Castle Hill?
How long does a home extension take to build in Castle Hill?
Can I live at home during the extension?
Should I extend out or add a second storey in Castle Hill?
Will the extension match my existing brick house?
How will I know what is happening during my extension?
Are you licensed and insured?
Extend your Castle Hill 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.
