Why floors slope on stumped homes
Your floor is a platform resting on bearers, which rest on stumps. When a stump sinks or its top rots away, the bearer above it drops by that amount and the floor follows — which is why slope on a stumped house is such an honest symptom. Unlike cracks (which can be cosmetic) or sticking doors (which can be humidity), a floor that has dropped has dropped for exactly one reason: something under it went down.
The direction tells you where. Floors falling toward an external wall point at the perimeter stumps on that side — commonly the wet side of the house, near failed gutters or garden overwatering. A dip in the middle of a room points at an internal stump, which carries more load than owners expect.
How much is normal?
Almost every pre-1970s house is a few millimetres out somewhere, and engineers typically treat gentle, long-stable slope as acceptable. As a homeowner rule of thumb: 10 mm across a room is character; 25 mm or more, or any slope you can feel underfoot when walking, deserves investigation; and any slope that is measurably worse than six months ago matters more than its absolute size. Trajectory beats magnitude.
Measuring it properly
The marble test finds the direction; a straight edge finds the number. Lay a 1.2 m spirit level (or any straight board with a level on top) across the floor in several directions, note the gap under the raised end, and write the measurements on a sketch floor plan with the date. Repeat in three and six months. This dated record is genuinely valuable: it converts "the floor feels worse lately" into evidence a contractor can price against and an engineer can interpret.
Slope vs bounce
A floor can be level but springy — that's usually a bearer or joist problem, or stumps missing their load entirely, and it's covered separately in bouncy and spongy floors. Slope plus bounce in the same area strengthens the stump diagnosis considerably.
What to do next
Cross-check the other symptoms — cracks and sticking doors in the same zone — then look under the house if access allows (the self-check guide covers what to look for). Re-levelling is part of every restump quote, so if the signs add up, the next step is simply knowing the fair price before inviting quotes.
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Common questions
Can a sloping floor be fixed without full restumping?
Often. If the affected stumps are localised, partial restumping re-levels that section. Packing (shimming existing sound stumps) is cheaper again, but only a stopgap when the stumps themselves are failing.
Will re-levelling crack my plaster?
It can — the house is being pushed back toward a shape it has slowly left. Good contractors lift in small increments over days to minimise it, and warn you honestly. Budget for some patching and painting after any full re-level.
How level will the house be afterwards?
To the levelling standard in the quote — which is why that line matters. 'Practical level' (within a few millimetres) is the usual standard; laser-flat costs more jacking time and raises the plaster-cracking risk.