Uneven floors: causes, costs and real fixes
A sloping floor is information. Read correctly, it tells you what's happening under the house and what it will cost to fix. Here's the translation.
The four causes, from cheap to serious
- Packing failure ($): old hardwood packers between stump and bearer compress or fall out. Localised dips; the fix is re-packing on sound stumps — genuinely cheap when it's the real story (it's the story cheap quotes always tell; it's true maybe one time in five).
- Individual stump settlement ($$): a few stumps sinking or rotting. Fix: partial restump of the affected section, $3,000–$7,000.
- Widespread stump failure ($$$): same-age stumps failing across the house — the slope is house-wide, doors misbehave everywhere. Fix: full restump with levelling, $12,000–$22,000 for a typical 3BR.
- Bearer/joist decay ($$–$$$): the stumps hold but the timber they carry is sagging or borer-eaten. Often discovered during restumping — the right time to fix it, while the floor is accessible.
If sloping floors have brought cracking walls along for the ride, run the cracks through the crack severity checker — width, pattern and behaviour together tell you whether the movement is seasonal or structural.
What "re-levelling" really means
The house is lifted in small increments — millimetres at a time, across multiple points, sometimes over days. Lift too fast and you crack plaster, pipes and windows. When a house has sat low for decades, a good contractor may deliberately leave it slightly shy of perfect to protect finishes, and will tell you so up front. Distrust anyone promising "perfectly level in a day" on a badly sunk home.
What levelling can't fix
Floorboards that were sanded flat while the floor was sloped, doors planed to fit crooked frames, and benchtops installed level on unlevel floors will all reveal themselves once the house is straight again. Budget a small allowance for post-level adjustments — an honest quote mentions this; a sales pitch doesn't.