When it comes to how ‘at risk’ a building is to damage, a lot depends on its age and condition. Regular maintenance is important, to make sure the essential elements and materials of a building are doing their job. A poorly maintained roof, for example, can lead to internal flooding, if there was a torrential downpour and the roof has tiles or slates missing, allowing water to pour in.
Structural problems
One of the biggest causes of gradual damage to property is subsidence. This is a structural problem, which can cause a great deal of expense and stress to the owners. It’s caused when the foundations of a building sink into the subsoil. This can be caused by unsuitable soil quality, above ground or underground water leaks, drought, tree roots, underground mining and other causes. When this occurs, it can cause visible cracks in the walls, pull doors and windows out of alignment, and slowly damage the structure of the building to become an unsafe place for residents and users.
There’s often examples of settlement in new-builds, as the materials dry out, the concrete cures and the building settles and finds its own level. This is not the same as subsidence, which is when a long-established problem causes parts of a building to sink at different rates. The eventual outcome of this will lead to part of a building to collapse, as you often see on old, derelict properties.
Other causes of structural movement are heave and landslip. Heave is the opposite of subsidence, as the ground beneath a building rises up, rather than falling. This again can be caused by flooding or water leaks, or by long-established tree roots near the property. If a property is moving sideways, then this may be due to landslip. You often see this on buildings built on sloping ground, or with sloping or eroded ground below them. This is common in coastal properties, where erosion has occurred due to weather conditions.
Underground movement
A classic example of subsidence is a leaking gutter or gulley that is causing water to wash away the soil around or beneath foundations. This can cause the foundations to lose their strength, and can even damage the foundations themselves, weakening the concrete. Over time the weight of the structure bearing down on the foundations can cause it to fracture or break completely. This will show itself above ground as a crack in the wall. The problem can be complicated further by the subsidence’s proximity to windows and doors, for instance, where the wall load will be redistributed anyway, due to lintels and loads from above.
Subsidence due to underground water leaks, a shattered drain for example, will only manifest itself over a long period of time, and the first sign of anything wrong will be the appearance of cracking above ground. There are two categories of movement caused by subsidence – historic movement and active movement. Historic movement is subsidence that has caused problems in the past, but has stopped when it has encountered something more solid, or been repaired and rectified by professionals. Active movement will still be causing problems and will continue to do so, until the issue is addressed.
Solving subsidence
Subsidence won’t magically rectify itself – unless the foundation settles on something solid, such as a level shelf of rock – and will only get worse, so the sooner you contact an expert and begin the repair process, the better. The best way is to underpin the building, which involves excavation and strengthening the foundations, but if a water leak is involved, this will need to be remedied too.
Subsidence can usually be fixed, but it can be extremely expensive. It can damage the financial value of your house, as well as its structure. It may also cause you problems with insurance claims, if the problem is a longstanding one that has been identified in the past, by a surveyor or valuer, so don’t delay if you suspect subsidence is becoming an issue.
Liam Hanlon, managing director of The Forshaw Group, is currently Chair of the Subsidence Forum, the Industry Home for Subsidence. The forum is designed to highlight subsidence matters for homeowners, insurers, local authorities, repairers and professionals. The forum is open to any organisation or individual involved with insured subsidence risk. As Liam comments, “I’m very pleased to be involved with the Subsidence Forum. It plays an important role in raising concerns and awareness of subsidence issues and how they can be addressed. Working together to jointly solve problems, advance standards and practice, and enhancing the effectiveness and profile of the industry, is to the benefit of everyone involved.”
