Ask a contractor to make your floor “level” and you’ve asked a harder question than it sounds. Every home settles somewhat over its life, timber shrinks and swells, and Wagga’s reactive clay is never entirely still. A re-levelling or underpinning job that promises a mathematically perfect, laser-flat floor everywhere in a sixty-year-old house isn’t being straight with you, and chasing that target can do more harm than good. This guide explains what tolerance actually means in a re-levelling or underpinning quote, what’s realistic to expect, and how to tell a fair target from an oversold one.
What “level” actually means in a re-levelling job
A floor level survey doesn’t just confirm that a room “feels” sloped; it produces a map of measured heights across the floor, usually taken with a laser or hydrostatic level at a grid of points, so the amount and direction of any fall is a number rather than an impression. That survey is the starting point for any re-levelling or underpinning quote, because it defines both the current problem and the achievable target.
“Level” in that context rarely means dead flat everywhere. It means bringing the floor back within a tolerance range that a structural engineer or licensed specialist considers acceptable for the age, construction and condition of your specific home, not an absolute zero-millimetre standard applied uniformly to every house in Wagga.
Why zero tolerance isn’t realistic, or necessary
Three practical reasons sit behind this:
Old materials have their own history. A timber floor that’s carried decades of seasonal movement has usually developed some permanent set in the bearers and joists, separate from the stump movement being corrected. Forcing that timber back to an artificial zero can introduce new stress, new squeaks and, in some cases, new cracking in skirtings and cornices that were previously stable.
Chasing the last few millimetres has diminishing returns. Bringing a badly sloping floor from a 60 mm fall down to 10-15 mm delivers almost all of the practical benefit: doors close properly, furniture stops rocking, water stops pooling towards one side of a wet room. Squeezing that last 10-15 mm down to zero adds cost and risk without a proportionate improvement in how the house lives day to day.
The ground keeps moving. Wagga sits on highly reactive clay that continues to shrink and swell with the seasons even after a repair. An engineer designing a re-levelling or underpinning solution factors in some allowance for that ongoing movement rather than pretending the clay will now sit still forever. Our guide to screw pile vs concrete underpinning covers how the underlying support method is chosen with that longer-term behaviour in mind.
The tolerance figures specialists typically work to
There’s no single number written into a contract for every home, because the acceptable tolerance depends on construction type, the age and condition of the structure and what an engineer judges appropriate for that specific building. That said, many NSW building consultants and specialists use rule-of-thumb gradients as a starting reference point when discussing a realistic target with a homeowner:
| Rough gradient | Approx. fall over 10 m | How it’s generally regarded |
|---|---|---|
| Better than 1:600 | Under about 17 mm | Rarely noticeable in daily use |
| Around 1:400 to 1:600 | 17-25 mm | Commonly used as a practical target for an older re-levelled home |
| Around 1:200 to 1:400 | 25-50 mm | Often noticeable underfoot; usually the trigger for looking at re-levelling in the first place |
| Worse than 1:200 | Over 50 mm | Typically considered for structural correction rather than living with |
These figures are indicative reference points, not a legislated standard, and they are not a substitute for a project-specific target set by the inspecting engineer or licensed specialist for your particular home. A new slab re-levelled with resin injection might reasonably be targeted much closer to true level than a sixty-year-old timber floor with decades of accumulated timber movement, simply because the underlying materials behave differently. Our resin injection underpinning guide explains how that lift is monitored millimetre by millimetre during the injection process itself, which is part of why slab jobs can often target a tighter number than a timber-floor job.
How the target tolerance is set and confirmed
A properly run re-levelling or underpinning job doesn’t leave the tolerance question to chance on the day:
- Pre-work survey. Floor levels are recorded before any lifting begins, giving a documented starting point.
- Target discussion. The specialist or engineer explains what’s realistically achievable for your construction type and condition, and what target they’re working to, before the quote is finalised.
- Staged lifting. Work proceeds in small increments, watching for new cracking or resistance as levels come up, rather than forcing the whole lift in one movement.
- Post-work survey. Levels are re-shot on completion and compared against the original map, so you receive documented before-and-after figures rather than someone’s opinion that “it feels better”.
If a contractor can’t tell you what tolerance they’re aiming for and can’t show you a level survey to confirm it was met, that’s a fair question to ask before signing anything.
What happens if the target tolerance can’t be reached
Occasionally a specialist stops a lift short of the original target, and that’s not automatically a failure of the job. Reasons this happens include reaching the point where further lifting risks new cracking in masonry or plasterboard, hitting resistance from services (pipes, ducting) running through the sub-floor, or the engineer judging that the last few millimetres carry more risk than benefit for that specific structure. A transparent contractor explains this on the day and documents the final levels achieved against the original target, rather than quietly under-delivering without saying so.
Does the house need monitoring after tolerance is achieved?
Usually, yes, at least informally. Because Wagga’s clay keeps moving seasonally, a floor that’s brought within tolerance this year can, in principle, start to drift again over subsequent wet-dry cycles, particularly if the moisture conditions that caused the original movement (poor drainage, a leaking pipe, a thirsty tree) haven’t been addressed. Photographing crack widths, keeping the post-work level survey on file, and having drainage and garden watering managed sensibly around the house all protect the result you’ve paid for.
FAQs
Should I insist on a perfectly level floor?
Generally no. On an older home in particular, forcing a floor to an absolute zero can cause new problems elsewhere in the structure without a meaningful improvement in liveability. A sensible, engineer-set tolerance that removes the practical symptoms (sticking doors, rocking furniture, water pooling) is usually the better outcome.
What tolerance is realistic for a timber floor re-level in Wagga?
Many specialists work towards a gradient in the order of 1:400 to 1:600 for an older timber floor, though the right figure for your home depends on its specific age, condition and the extent of the original movement. Ask your specialist what target they’re working to before the job starts.
Can a slab be re-levelled more precisely than a timber floor?
Often, yes, since resin or grout injection is monitored continuously during the lift with high-precision level instruments, which can allow a tighter target than jacking and packing an older timber floor with its own accumulated movement history.
How do I know if the tolerance was actually achieved?
Ask for the before-and-after level survey. A specialist who measured your floor before starting should be able to show you the same measurements taken again on completion, in writing, not just a verbal assurance.
Get a realistic target for your home
If your floors are sloping and you want an honest answer about what’s achievable, not a sales promise of a laser-flat result, get a free quote and an independent licensed contractor can survey your levels, explain a sensible tolerance target for your specific home, and confirm it in writing once the work is done.