The Hills Shire · postcode 2756
Knockdown Rebuilds in Cattai: Rethink Where the House Sits
On ten acres, the old house's footprint is the least interesting place to rebuild.
Suburban knockdowns go back on the same slab because there's nowhere else to go. In Cattai there is. The river, the bush, the fall of the land and the afternoon sun all argue for somewhere better, and a rebuild is the one chance to listen.
Short answer
Where should a knockdown rebuild go on a Cattai acreage property?
Wherever the land works best, which is often not the old footprint. Site the new home above the Hawkesbury flood planning level, clear of the bushfire asset protection zone limits, with good access and solar orientation, and near a septic area that can handle the new bedroom count. Confirm the dwelling entitlement on the planning certificate first. Building at mid-spec costs about $2,310 to $2,780 per m² on Rawlinsons with the Hills loading.
Written and reviewed by Oliver Alameri
Licensed builder, NSW Contractor Licence 487805C · Founder, Buildana
Fact-checked
Start with the river
The Hawkesbury floods, and not gently. Recent years proved it. Low parts of Cattai's river flats sit well below the flood planning level council uses, and a new dwelling generally needs its habitable floors above that level plus freeboard.
On a big holding that's often easy: move the house uphill. The old cottage may have been built by the river for the view in a quieter decade. The new one can keep the view from higher ground, with a safe driveway out when the water rises.
- Flood planning level for the property, from council
- High ground with a flood-free access route
- Old footprint kept only if it's genuinely the best spot
- Outbuildings in the flood zone reconsidered too
A rebuild is the only time you get to move the house. Don't waste it on the old slab.
Then the bush and the sun
Cattai National Park and the surrounding bushland put most holdings on bushfire-prone land. Distance from the bush sets the BAL, and on acreage you can often choose that distance. Shift the house fifty metres and the rating, the glazing spec and the build cost can all drop.
Orientation comes free on a big lot. Living areas facing north, bedrooms to the east, garage and service rooms to the west. It's simple, and it saves on heating and cooling for the life of the house.
Want a second opinion on where to rebuild?
Send me your Cattai property details. I'll look at flood, bush and aspect across the holding and suggest where a new home would sit best.
0476 300 300What the old place leaves behind
Rural demolitions are bigger than suburban ones. There's the house, plus sheds, carports, old septic tanks, fuel storage and decades of farm odds and ends. Older outbuildings often contain asbestos sheeting, which needs licensed removal before anything is knocked down.
The old septic system is decommissioned properly, and the new house gets a wastewater system sized for its bedrooms, with an effluent area on suitable ground away from creeks and bores.
And check the planning certificate for the dwelling entitlement. Replacing a lawful dwelling is usually straightforward, but it's worth confirming before demolition.
Approvals and cost
Rural rebuilds with bushfire and flood mapping usually need council consent: a DA lodged with The Hills Shire and assessed in about 11 to 15 weeks, longer if bushfire referral is required.
On Rawlinsons' Sydney baseline with the Hills' 1.05 loading, the house itself comes to roughly $2,310 to $2,780 a square metre, finished to a sensible middle standard. Driveways, services, wastewater, tanks and bushfire construction add to that and are priced from the site.
Before you pick the new site
What I'd check on any Cattai acreage rebuild.
- 01
What is the flood planning level on the property?
- 02
Is there a flood-free route out?
- 03
How far is each candidate site from the bush edge?
- 04
Which way does the land face?
- 05
Where can a new effluent area go?
- 06
Does the planning certificate confirm a dwelling entitlement?
Knockdown rebuilds in Cattai
Do I have to rebuild on the same spot?
No. On acreage the new house can usually go elsewhere on the holding, subject to setbacks, flood, bushfire and wastewater requirements.
Is Cattai flood-affected?
Parts near the Hawkesbury River are. Council's flood planning level for your lot sets how high habitable floors must be.
Can I keep the old house while building the new one?
Sometimes, as temporary accommodation, if the consent allows it and the old house is demolished before the new one is occupied.
What happens to the old septic tank?
It's pumped out and decommissioned properly, and a new system is designed for the new house's bedrooms and soils.
Sources and references
Costs are from the Rawlinsons handbook with the local cost index applied; rules and timeframes are checked against the sources below.
New house, better spot.
A Cattai knockdown rebuild sited for the river, the bush and the sun.