Unless you built your house with your own hands, it’s unlikely that you’ve ever considered the foundations upon which your home sits. We often take solid foundations for granted and it can come as quite a shock when something goes wrong.
Subsidence is one of the most common foundation issues. The term refers to movement in the foundations of your building, causing it to shift and eventually sink. The leading causes are:
A reduction in the ground water table in clay soils caused by a long dry spell
Collapsing mines and culverts near your home
Trees and bushes growing under the foundations in clay soil
Soil washing away from the foundations caused by a broken drain or water mains.
The good news is that if it is identified early enough, subsidence can be easy and relatively cheap to rectify. This makes it really important to be able to spot the signs of subsidence with ease.
Anything more than 3mm wide is a warning sign. Smaller cracks are often perfectly harmless signs of settlement in newer houses, or a demonstration of the flexible nature of older builds. Small cracks in older houses sometimes appear during the summer but close up again in the winter when the building absorbs more moisture.
Interior walls might be showing signs of subsidence if you notice cracks in plasterwork or a rippling effect in wallpaper. Most plaster cracks are caused by damp or moisture, though, so don’t worry too much about hairline cracks in older walls, particularly in bathrooms and kitchens. If you notice cracks spreading and getting wider, call a specialist.
One of the most obvious signs of subsidence is when doors begin to stick without cause. Wooden doors often stick in hot or wet weather, but doors or windows that become stiff or stick for no particular reason could be acting as an early warning sign.
Floorboards that appear to have risen or sunk can be another sign of subsidence. Again, there are several innocent explanations for this, including the fact that wood changes shape over time in differing conditions. If you notice a long-term trend of sinking or rising boards, make sure to investigate further. Signs of subsidence will probably need to be monitored and measured for a long period before any rectification work can take place. This process can take up to a year, so keep a log of the various signs and when they occur. A chartered surveyor will be able to work out whether you have subsidence and recommend next steps. On the positive side, the majority of the leading building and contents insurance companies provide cover for subsidence, helping to reduce the overall cost of the issue.