A client in Figtree once rang me about six weeks after we'd finished the drawings, sounding a bit sheepish, to ask when the house was coming down. Fair question. From where she sat nothing had happened since the day she'd signed off on the plans. From where I sat we'd been busy the whole time — hazardous materials report ordered, three demolition quotes chased, the electricity distributor's disconnection form sitting in a queue somewhere, and a surveyor booked to photograph the neighbours' brickwork before anything shook.
That's the honest shape of a knockdown rebuild. The house coming down takes about two days. Getting to the point where it can legally come down takes months, and none of it is visible from the street.
I've written the money side of this separately, in what a knockdown rebuild costs in the Illawarra, and the should-you-even-do-it side in renovate or knock down and rebuild. This one is the middle bit. The process.
Two approvals, not one
The first thing that catches people is that demolishing the old house and building the new one are separate approvals. Different assessments, different conditions, and in principle you could get one without the other.
You can run them separately. Some people do, usually because they want the block cleared before the new design is settled. I'd talk you out of it nine times in ten. Bundling the demolition into the same development application as the new dwelling means one assessment, one set of conditions, one lodgement fee, and no window where you're standing on a vacant block with no approved house to put on it. That window has a way of stretching. Interest rates move, a neighbour objects to something in the new design, and now you're paying rates on dirt.
Whether the new house goes through complying development or a full DA depends on the block and the design, and I've set out that fork properly in CDC versus DA in NSW. Worth knowing that demolition can sometimes be done under complying development where the new house can't, or the reverse, so the two halves don't always want the same pathway. The NSW planning department publishes the state-level policies, and your council's development control plan is where the local overlays sit.
One thing that quietly rules the timing: heritage and conservation areas. If your street is in one, or the house has any listing on it, demolition is a genuinely different conversation and you want to know that on day one, not after you've paid for a design.
The hazardous materials survey
Anything built in the Illawarra before the early nineties, assume asbestos until a report says otherwise. Fibro cladding, eaves, the sheet behind the old bathroom tiles, the backing on the meter board, sometimes the vinyl floor and the glue under it. It's extremely common down here and it's not a disaster. It just has to be handled properly, and it has to be found before the machine arrives, not during.
So a licensed assessor walks the house and writes a hazardous materials report. That report is what the demolisher prices off, and it's what determines whether the removal work needs a licensed asbestos removalist. There are thresholds around how much and what type triggers which licence class, and SafeWork NSW is the authority on all of that. Don't take the demolisher's word for the licensing question. Ask to see the licence.
Two practical things. First, a demolition quote given before the survey is a guess, and it will move. I've seen it move by five figures on a house that turned out to have asbestos sheeting under a later brick veneer skin. Second, if the report finds a lot of it, the removal happens as its own job before the main demolition, with its own controls and its own clearance certificate. That's another week or two in the program.
Lead paint on older weatherboard, and the odd bit of synthetic mineral fibre insulation, turn up in the same survey. Less drama, still has to be managed.
Disconnecting the services
This is the step that eats the most calendar time and gets the least attention, so I'll be blunt about it: start it early.
Power has to be disconnected and, in most demolition cases, abolished — meaning the connection point is removed entirely, not just switched off. That goes through your electricity distributor rather than your retailer, which trips people up, because the retailer is who they've got a relationship with. Water and sewer are the water authority's business, and the sewer connection usually gets capped rather than removed, because the new house is going to want it. Gas is a disconnection and a meter removal. Telecommunications is its own separate form.
Every one of those is a different organisation with its own lead time, and the lead times don't run in parallel as neatly as you'd hope. A demolisher will not touch a house with a live service on it, and nor should they.
The one worth thinking about hardest is sewer. Where your existing junction sits relative to where the new house wants its wet areas is a real design constraint, and if the new plan needs the connection moved you're into an application with the water authority, possibly a plumber's plan, possibly a build-over-sewer assessment if any of the new structure lands near the main. Better to know this while the plan is still on a screen and easy to move.
The dilapidation report
Before anything vibrates, someone photographs the neighbours' houses. Cracks in render, the state of the driveway, the fence line, the retaining wall on the boundary. That's a dilapidation report, and it's usually a condition of consent on any demolition tight to a boundary, which around here is most of them.
It protects you far more than it protects them. Old brickwork in Wollongong is full of pre-existing cracks. Without a dated photographic record from before your excavator arrived, every one of those cracks becomes yours the moment the neighbour notices it. I've watched a job get held up for a month over a hairline crack in a garage slab that was in the report the whole time — the report ended it, but only because it existed.
Go and talk to the neighbours yourself before the surveyor knocks on their door. Two minutes of warning turns an intrusion into a courtesy, and you're going to be making noise next to these people for the better part of a year.
Site controls and the conditions nobody reads
The consent comes with conditions, and the demolition-stage ones are usually some combination of hoarding or temporary fencing to the street, sediment and erosion controls, a shaker grid or rumble strip so trucks don't drag mud onto the road, protective fencing around any tree that has to stay, and set hours for noisy work.
Tree protection is the one that bites. If council has conditioned a tree to be retained, the protection zone around it is typically bigger than people expect, and you cannot park a machine in it, stack materials in it, or run a truck across it. A demolisher who ignores that can cost you a fine and, worse, a tree that dies eighteen months later and gets traced back to root compaction during demolition. Point the protected trees out on site, on day one, to the person actually operating the machine.
Where the demolition money goes
Roughly, and I'm not putting numbers on this because they move with the site: the machine time is the small part. What drives a demolition quote is what has to be sorted and where it has to go. Asbestos removal and disposal is its own line. Clean brick, concrete and metal can be separated and recycled, which is cheaper than landfill. Mixed waste goes to a tip that charges by the tonne and pays a levy on top of it, and the NSW waste levy applies across the Illawarra, so tip fees are a genuine driver rather than a rounding error.
Then there's access. A demolisher who can back a truck into the site and load directly is cheaper than one who has to barrow material out to a truck parked on the street, and a steep or narrow block can put you in the second category. Same constraint that makes the build harder, which is more or less the theme of building on awkward land generally.
Slab removal is the other variable. Some jobs pull the old slab because the new house doesn't suit its footprint or the footings underneath it are in the way. Some leave it and work around it. Ask which one your quote assumes, because it's a chunk of money either way and I've seen it excluded quietly.
The dead weeks
Here's the part I wish more people budgeted for. Once the house is down, you're not starting the new one the next morning.
The block gets cleared and levelled. Then there's usually a geotechnical investigation, or a second one, now that the machine can actually get to where the new footings go — you'd be surprised what turns up under a fifty-year-old house that the original bore holes missed. The surveyor comes back to set out the new building. The engineer finalises the footing design against whatever the geotech found. Then the slab trades get booked, and they get booked into a queue.
Call it a few weeks in a good run, longer if the geotech turns up something. If you're renting through the build, that's rent you're paying for a period where nothing appears to be happening, and it's the single most common source of "why is this taking so long" phone calls. The overall build duration question is covered in how long it takes to build a house; this bit sits in front of all of that.
There's also a fair chance you're still living in the house right up until demolition week, which sounds efficient and usually isn't. Moving out under time pressure while a demolisher waits is nobody's good week. Give yourself a buffer.
The order I'd run it in
Concept design and a genuine feasibility read on the block first, because there's no point costing a demolition for a house that can't be approved. Then the hazardous materials survey and the survey of the land, because both feed everything downstream. Then the approval, with demolition and the new dwelling in the one application. Then the service disconnections, started the day the approval lands, not the week before the machine is booked. Then demolition and clearance. Then the setout, the engineering, and the slab.
The mistake I see most often is people leaving the disconnections until the demolisher gives them a date. By then you've got a machine booked and a utility telling you six weeks.
We run knockdown rebuilds across Wollongong, the Illawarra and the Southern Highlands, and we handle the approvals, the demolition and the build as one job rather than leaving you to coordinate four different outfits — that's set out on our knockdown rebuild page. If you've got a tired house on a block you'd rather keep, send through the address and a couple of photos on the contact page, or call 0434 037 851 and I'll give you an honest read on what the demolition side of it looks like before you spend anything on a design.
Want a hand with this at your place? Get a free quote or call 0434 037 851.