Why do floors slope in older houses?
Floors in older properties slope for several reasons, some harmless and some problematic: foundation settlement, structural damage, unlevelled construction, soil movement and the ageing of building materials. Anyone who has toured an older property may have noticed uneven or sloping floors.
- Settlement: decades or centuries after construction, many older buildings experience settlement, where the building's weight causes a gradual sinking into the ground. This can lead to minor floor sloping, which is usually not a cause for alarm.
- Structural damage: more serious. Damage from water or poor maintenance can weaken supports and joists (the timber beams that carry a floor), leading to noticeable sloping.
- Soil movement and tree roots: significant soil movement, or tree roots close to the building, can affect the foundation and cause it to shift, with the floor sloping as a result.
- Construction methods: methods and regulations were much less exact in the past and standards may not have been as stringent, which can leave floors uneven.
Seen cracks at a home you are buying? Get a survey price for the home you are buying.
Are sloping floors dangerous?
A significant slope can compromise a property's structural integrity. It can set off a domino effect in which walls crack and windows and doors misalign.
- Safety: uneven surfaces can be inconvenient and unsafe, unbalancing furniture and increasing the risk of trips and falls.
- Cost: fixing sloping floors can be costly, especially where it is linked to foundation issues.
- Value: unchecked sloping floors can affect a property's resale value.
How are sloping floors fixed?
The repair depends on the underlying cause, and the complexity varies.
| Cause | Typical remedy |
|---|---|
| Structural damage | Address the damage first: replace decayed wooden beams and joists, or treat the property to prevent further damage from root intrusion or dampness |
| Abnormal foundation settlement or soil movement | Underpinning (strengthening or deepening the foundations) |
| Construction discrepancy | Floor levelling, such as applying a levelling compound or installing a self-levelling subfloor |
Should homebuyers worry about sloping floors?
Yes and no. A slope could indicate serious structural issues and lead to costly repairs. Equally, it is not always a sign of major problems and may be manageable with professional help.
Buyers need not be deterred from older properties, with their craftsmanship, period features and character, but they should be diligent and find out what is causing the slope.
What to look for when viewing a property
- How noticeable the slope is: minor or significant.
- Cracks in walls.
- Windows and doors that are misaligned.
- Signs of water damage, poor maintenance or decayed timber.
- Large trees close to the building.
- Furniture that sits unevenly, and trip hazards.
What to do next
- Note where the floors slope and whether there are related wall cracks or misaligned doors and windows.
- Commission a detailed building survey to assess the cause.
- Get an accurate diagnosis and a full cost estimate for any remedial work.
- Take the likely repair into account before committing to the purchase.
What a survey can — and cannot — tell you
A building survey provides an informed assessment of the visible condition of a property. Inspections are non-intrusive and limited to areas that are accessible at the time of inspection.
A detailed building survey by an experienced professional can assess sloping floors, reveal underlying serious issues and guide on the steps needed if remedial action is required.
- The extent of floor sloping and unevenness.
- Wall cracks and misaligned windows and doors.
- Visible signs of water damage, decay or poor maintenance.
- Trees near the building that could affect the foundations.
However, there are limitations to what a survey can determine without intrusive investigation.
- Joists and supports beneath floor coverings are usually hidden from view.
- Foundations and soil conditions cannot be seen at a visual inspection.
Where higher-risk indicators are identified, further specialist or intrusive investigation may be recommended.
Frequently asked questions
Is a sloping floor in an old house normal?
Often, yes. Many older buildings settle gradually over decades or centuries, and minor sloping from settlement is usually not a cause for alarm.
When is a sloping floor a structural problem?
When it results from structural damage, such as weakened joists and supports, or from significant soil movement or tree roots affecting the foundation. A significant slope can lead to wall cracks and misaligned doors and windows.
Can sloping floors be fixed?
Yes. Depending on the cause, repairs range from floor levelling with a levelling compound or self-levelling subfloor, through replacing decayed joists, to underpinning for foundation problems.
Do sloping floors affect house value?
Unchecked sloping floors can affect a property's resale value, and repairs linked to foundation issues can be costly.
