The word subsidence is guaranteed to strike terror into the hearts of many owners – and with good reason.
It can cause major damage to property and sometimes even require the total demolition of the property concerned.
What is subsidence?
Subsidence just means a ‘falling away’ – usually of the ground. It doesn’t necessarily have to be associated with a property because, for example, something like a garden area can suddenly start to subside too.
However, for property owners, the worrying aspect of subsidence is when it takes place beneath or adjacent to property. That’s because it can lead to major structural damage.
To illustrate the position, the chances are that your property, if built from the early-mid 19th century onwards, is constructed more-or-less flat and level with the land it stands on. If the ground underneath one part of it starts to sink down, then part of your property is going to start to sink with it. That might lead to the affected parts of the property ‘parting company’ with the other parts of the building that aren’t sinking.
It’s also worth remembering that sometimes the ground can rise up as well as sink. The effects on your property may be broadly the same and this condition is called ‘heave’.
What causes subsidence?
The effect can arise for any one of several reasons, including:
- shallow and/or poorly laid foundations – this is more commonplace on older properties;
- the underlying soil drying out and shrinking at uneven rates over time;
- natural geological events, such as earth tremors (yes, they do happen in the UK);
- human-related geological events, typically including old coalmines collapsing downwards or other such things;
- erosion of the subsoil – that might involve underground streams shifting their course or a leaking water main eating away at your foundations;
- plants and trees – because if they’re planted too close to your property, they may take too much moisture out of the soil leading to shrinkage.
In fact, there are far too many potential causes to list here.
Classic symptoms of subsidence
It’s important not to become obsessed with looking at every small crack in your plasterwork and worrying whether or not it’s home subsidence. In practice, the vast majority of cracks in plasterwork and even external pointing between bricks are usually nothing more serious than the drying out of materials over time.
However, be alert for:
- larger width cracks that exceed the width of a flat smaller denomination coin (say around 3-4mm);
- cracks that are significantly wider at the top than the bottom;
- splits in a brick;
- diagonal cracks;
- sticking doors and windows;
- architectural components that are parting – examples might include external steps starting to tilt away from the wall they join or cracks between a room and an adjoining extension.
What you can do
There are certain steps you can take that might reduce the risk of at least some of the above problems coming to pass.
For example, you can avoid planting larger bushes and trees directly adjacent to your property. It is, of course, always advisable to be sure that you’ve had sight of a survey and looked carefully at your solicitor’s searches so that you’re aware in advance if your property resides in an area known for subsidence.
In many cases though, subsidence can arise with little prior warning or any past history. If you think you have detected it in your property, you should consult a qualified builder as soon as possible.
The good news is that there are treatments available for home subsidence though depending upon the severity of the condition, they may be expensive.
The insurance implications
Not all property policies will automatically offer cover for subsidence. Some may also exclude it in areas where it is known to be prevalent due to, for example, old mine workings.
The bottom line here is simple – read your policy carefully before purchase and if you have any doubts, ask for a specific comment from the potential provider about how they would treat subsidence claims.
Finally, read our guide to subsidence.