Ask anyone who’s renovated an old home, and you’ll hear a familiar line: “You just never know with renovations”.
They’re not wrong. Renovations or even renovation quotes simply don’t behave like new builds. With a new home you can measure up, feed square-metre rates into a spreadsheet and have a price within a day. Old houses, on the other hand, have layers of history you can’t see.
People shrug and say it’s impossible to plan until demolition starts. But I don’t buy it. I call these the known unknowns. We might not see every risk at tender stage, but we can allow for them up front so you’re not blindsided mid-build.
The usual suspects? Two stand out every time:
- Asbestos, often buried under layers of old linings.
- Termite damage, invisible until walls are opened.
If you don’t price those risks before you start, they’re the ones most likely to derail a project.
There is a way to avoid all this, and it’s simpler (and less stressful) than you might think.
The 8-Week Forensic Prelim Plan That Saves Your Bacon
Here’s what I do (and what every builder should do) between receiving your plans and finalising the construction quote. It’s not glamorous, but it pays for itself:
- Walk the job with you, repeatedly. We “almost build” the project on paper and on site – talk through finishes, edges, junctions, and all the spots where assumptions hide. If something you’re imagining isn’t on the plans, we’ll surface it and price it NOW, not in week two of construction.
- Bring demolition specialists early for an asbestos sense-check. Age/style of the home gives us a good read. If we can confidently confirm it’s there, we include removal in the quote. If we can’t see it (often it’s buried under two or three layers of lining), we treat it as a known unknown and put in a clear allowance.
- Spell out allowances in plain math. For asbestos, I’ll budget $500 for testing/certification plus $35/m² removal, and estimate the likely area – say 100 m² – for $3,500. That figure sits inside your quote. If demolition proves there’s less (or none), you get the credit back. If there’s more, we’ve at least framed the cost honestly from day one.
- Be candid about termites. If there’s no visual evidence pre-start, we flag the risk. If it appears during strip-out, we deal with it. That’s not a pricing failure; it’s the reality of renovating. The key is that you knew the possibility existed, and we discussed it up front.
Timing matters: clients can be in prelims up to four months total (from design start to construction quote), and I’ll often spend 8–10 weeks of that window on walkthroughs and site time after I receive the plans. That’s how we collapse the “unknowns” and align expectations before construction begins.
Why This Approach Protects Your Budget (And Your Sanity)
- No “Day-1” variations. Nothing poisons trust like signing variation forms during demolition. Starting a project by paying surprise extras creates the worst possible tone; and you’re doing it before the work has really begun.
- Banks are far more flexible before you start. Wait until halfway through – after the quote has already blown past the obvious risks – and asking for extra cash is like patching a leaking roof in a cyclone. They’re tough to deal with on a good day; mid-build they’re even tougher. Price those allowances at the start, and the finance conversation stays simple.
What “Good” Looks Like In Your Renovation Quote (A Quick Checklist)
Use this with any builder. You’re looking for evidence that the known unknowns have been considered inside the number:
- A documented prelim process (multiple site visits; finish/fixture walkthroughs; time invested to “almost build” on paper before pricing).
- An asbestos plan: early demo check, plus a written allowance with testing, rate per m², and a quantity assumption (e.g., $500 testing + $35/m² × 100 m² = $3,500).
- A frank note on termite risk and how it will be handled if discovered.
- A clear statement about credits if allowances aren’t used; upfront, not as a favour later.
Renovations Don’t Go Over Budget by Accident. They Go Over by Omission.
Renovations will always carry a few mysteries – you can’t see through walls until you open them up. But that doesn’t mean you have to gamble your budget.
Plan for the “known unknowns,” price the obvious risks before you start, and you take the sting out of the surprises.
That’s the whole point of the eight-week forensic prelim: to surface every loose end before the first hammer swings, so you control the numbers instead of the numbers controlling you.
If you’d like to go a step further, I’ve put together a free guide:
The 5 Mistakes People Make When Planning Their Renovation (And How to Avoid Them)
Inside, you’ll learn:
- The #1 reason most quotes explode mid-build (and how to guarantee yours won’t)
- What most families underestimate about living through a renovation (and how to stay sane)
- Why choosing a builder who “dabbles” in renos can lead to disaster.
- The overlooked factor more important than price, inclusions, or promises.
Grab your copy here and sidestep the traps I see homeowners fall into all the time. It’s the simplest way to renovate with confidence, and make sure the only surprise you get is how smoothly everything runs.
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