A squeaking floor is not something that develops over time. It was built that way. The cause is almost always preventable at construction stage — and almost always comes down to what went under the first sheet.
It happened before the first sheet went down
A squeaking floor is not a maintenance issue. It's a construction failure that was locked in before the first sheet of particleboard or plywood ever went down.
This is worth being direct about because a lot of homeowners spend years accepting squeaking floors as a fact of life — oiling hinges, tightening screws, replacing boards. None of that addresses what's actually happening in the subfloor structure underneath.
The cause is almost always one of three things. All three are preventable. None of them fix themselves.
The three causes of subfloor squeaking
The adhesive failed. Liquid nails is used on most Sydney subfloors. It cures hard and brittle. A floor is a dynamic system — it moves constantly under foot traffic, furniture loads, and thermal cycling. Liquid nails doesn't accommodate that movement. It debonds. The gap between joist and sheet is where the squeak comes from.
The joist was crowned. Joists are not perfectly straight. When a joist has an upward bow in the middle — a crown — adhesive can't bridge the gap between the joist's high point and the sheet. You get contact at the ends and no contact in the middle. The sheet flexes underfoot and produces noise.
The substrate moved. If the slab wasn't walked and high points identified before framing, those points get locked into the floor structure. The frame sits on a slab that isn't flat, the sheet bridges a gap, and it flexes every time someone walks across it. No amount of adhesive fixes a sheet that's bouncing.
Why liquid nails is the wrong product
Liquid nails is cheap, available at every hardware store, and used by the majority of subfloor installers in Sydney. It's also the wrong product for structural subfloor bonding.
The issue is not initial bond strength — liquid nails adheres fine on day one. The issue is what happens under cyclic loading over time. Every person who walks across a floor deflects that floor a small amount. Thousands of deflections per year. Liquid nails cures rigid and doesn't absorb those deflections. It fatigues and debonds — not everywhere at once, but at the points where movement is highest.
Polyurethane adhesive is the correct product. It cures with a degree of flexibility. It doesn't fatigue under cyclic loading. Applied in a 30mm bead across the full width of the joist, it provides both bonding and cushioning — which is part of why it eliminates the squeak rather than just delaying it.
This is one of the things that genuinely distinguishes quality subfloor framing from minimum-standard work. The product costs more. The time to apply it correctly costs more. The result is a floor that doesn't squeak in year one or year ten.
What correct subfloor construction looks like
The slab is walked at all wall locations before any frame goes in. The highest point becomes the datum for the entire structure. All packing goes at slab level — directly on the slab — not disguised at top-plate level where it's invisible.
Every joist gets a straightedge check before sheeting starts. Crowning is identified and planed. This takes time. It's the time most subfloor installers skip.
Polyurethane adhesive only, in a 30mm bead for full coverage. Ring-shank nails go in first to hold the sheet while the adhesive sets, then a full structural screw fix-off after installation. Both tongue-and-groove and butt joints get adhesive. Expansion joints are installed to manufacturer requirements.
Done correctly, this produces a floor that won't squeak. The sequence is not complicated. It just takes longer than the minimum.
Can existing squeaking be fixed?
Sometimes. The honest answer depends on what the cause is and how accessible the subfloor is.
If the house has a raised subfloor with crawl space access — common in Sydney's federation and interwar homes — joists can be re-glued and screwed from below at the squeak points. This works reasonably well for localised adhesive failure.
If the floor is on a concrete slab with no access from below, and the sheeting is intact, options are more limited. Long screws driven at an angle from above, into the joist below, can eliminate localised squeaks. Full resolution often requires lifting the floor and starting the subfloor correctly.
If the floor is being retiled or replaced anyway, it's worth pulling the sheeting back to slab level and reinstating it correctly rather than re-sheeting on top of a bad substrate. The substrate doesn't improve under new sheets.
For homes on raised timber subfloors — particularly the federation and interwar homes common to Sydney's Inner West and North Shore — squeaking can also indicate stump settlement below the floor rather than just adhesive failure above it. If the stumps are failing, re-gluing the sheets treats the symptom. What restumping costs and involves in Sydney is worth understanding before committing to a subfloor-only repair.
Frequently Asked Questions
Are squeaking floors normal in older Sydney homes?
Common, yes. Normal, no. Most subfloor squeaking in older homes comes from original adhesive failing or timber joists that have dried and shifted over decades. Both are fixable — the question is whether it's worth the cost relative to the scope of other work being done.
Why is my brand new floor already squeaking?
Most likely the adhesive. Liquid nails — used on most new builds — cures brittle and debonds under foot traffic. If the floor is new and already squeaking, it's a construction issue, not a settling issue. In NSW, structural defects in new residential buildings are covered under the Home Building Act warranty provisions.
Can squeaking floors be fixed without replacing them?
Sometimes. From below (if there's access), joists can be re-glued and screwed. From above, long structural screws driven into joists at squeak points can resolve localised issues. Full resolution of widespread squeaking usually requires lifting the floor and reinstating the subfloor correctly.
How do I know if my joist is crowned?
A straightedge laid along the length of the joist will show it. Any gap between the straightedge and the joist of more than 2–3mm needs to be planed before sheeting. This check should happen at construction stage — not after the squeaking starts.
What's the difference between ring-shank nails and standard nails for subfloors?
Ring-shank nails have annular rings on the shank that grip the timber and resist withdrawal. They hold better under the cyclic loading a floor experiences. Standard smooth-shank nails can work loose over time, creating another source of movement and noise.
Sources & Further Reading