The symptoms of either problem may be very similar – in so far as cracks appearing in the plasterwork of interior walls. But subsidence is a potentially serious worry, with the possibility of serious damage to your home, whilst settlement is typically a minor phase causing little permanent harm to (mainly new) homes.
Subsidence, and repairs to the damage it causes, is often covered by your home’s subsidence insurance, whilst settlement is not.
The distinction between the two is therefore important, but how do you spot the difference?
- foundations are typically dug to bear the considerable weight of a building;
- but as the weight bears down, it compacts the ground – in a way that is designed to spread the load evenly – as the foundations are said to settle;
- this is the process of settlement – one which takes place in practically every new building;
- subsidence, however, may happen at any stage in a building’s life and results from the uneven shrinkage or swelling of the ground on which the foundations are laid, causing damage to the structure above;
- a mind’s eye picture is painted by a contributor to a discussion by the Money Saving Expert where settlement is described as like breaking in a new sofa, so that it comfortably take the shape of your bottom – every sofa does it, then stops, and there is no lasting damage;
- subsidence is like the leg falling off the sofa you just bought – it is immediately lopsided, falls to one side and becomes unusable;
- civil engineers, the David French Partnership, describes the process in somewhat more technical terms, of course, where settlement is the result of the building’s weight simply compacting the soil;
- subsidence is caused by shrinkage or swelling moving the ground in variable degrees away from the foundations, causing them to fail and the structure above to crack and collapse;
Spotting the signs
- confusingly, the signs are likely to be very similar – both processes made evident by faint cracks that appear in the internal walls and around weaker points in the plasterwork, such as window and door frames;
- the critical difference, however, is that cracking caused by settlement soon stops, without any lasting damage – whilst the cracks caused by subsidence continue to widen, often over a period of years, causing more and more damage as time goes on;
- in the initial stages, at least, it may be difficult to detect the different nature of the cracks as they appear;
- cracks caused by subsidence however, typically run vertically or horizontally and have a tapered characteristic, widening rapidly or slowly over time;
- therefore, once you have reported any concerns about the possibility of subsidence to your insurer, the first step is likely to be an instruction to professional surveyors or structural engineers to inspect the property and monitor signs of any further movement through the cracks lengthening or widening;
- because the speed at which subsidence may progress varies so widely, this monitoring process may take as long as 12 months or so, before the extent of any damage is fully assessed and remedial works advised.
In short, there are major differences between the causes and effects of subsidence and settlement respectively, although the initial signs and symptoms may be confusingly similar.
Further reading: Guide to subsidence and subsidence insurance