What are the causes of Subsidence?
Subsidence is such a serious problem for home and building owners and it’s essential the causes of it are known by as many people as possible. The causes are many and varied, but it’s important for potential homeowners and those looking to sell to ensure they know the risk of subsidence affecting their home. Some of the causes are man made, so it’s important that you know the possible impact of certain developments.
The cost of home insurance for subsidence will depend on whether the property has a history of subsidence. That’s why the causes of subsidence matter. Sudden and unexpected subsidence on a home with no history of it will, therefore, be under coverage which costs much less.
70% of UK ground subsidence cases are due to soil shrinkage, according to Quoteline Direct. Soil shrinkage is the changing density of soil based on moisture level. During extended dry periods, the soil loses moisture and shrinks, leading to more cases of ground subsidence. There are several varieties of soil types in the UK, some of which are susceptible to ground subsidence.
Clay and silt are far more likely to experience soil shrinkage because they are very porous cohesive soils, which means their volume will shrink and grow depending on their moisture content. If you live in an area with clay or silt soil then you are at a much higher risk of subsidence. If the soil in your area is sand or gravel, both of which are non-cohesive soils, then soil shrinkage will not be a factor.
According to Quoteline Direct, 20% of subsidence claims are due to water damage. Water can cause subsidence by coming out of leaking drains or burst water pipes. Leaking or rushing water will only affect gravelly or sandy soil, because it is poor at absorbing water, so will wash it away. This will leave a gap underneath your house and cause parts of it to sink.
Large or lots of trees near your home can also be a cause of subsidence. Large trees have large roots, and they can get very thirsty during the warmer months. They’ll suck out the moisture from the soil, causing it to shrink, and leading to ground subsidence. Certain trees, like oaks and willows, are more problematic than others. You should keep this in mind if you’re planning on planting any trees in your garden. If the problem does turn out to be this then tree removal may need to be in order.
Man made cavities
Old mines and certain mining methods can displace large volumes of soil or remove moisture from it. These can collapse several years after the mining has finished, meaning that it can catch building and homeowners completely by surprise, since they had no knowledge of a cavity beneath the ground.
You can use a chartered surveyor to assess whether the subsidence affecting your home was caused by mining. If it was caused by mining, then you can claim for it through your home insurance.
Constant traffic and nearby road or building works can cause enough vibrations to dislodge areas of soil underneath your home or building, leading to subsidence.
Poor compaction of soil during construction.
During the construction of a new house, the ground beneath should be compacted. This is the process of squeezing as much air and moisture out of the soil as possible, so as to reduce the soils’s ability to shrink due to changes in moisture levels. If this is not carried out, or not done properly, then the soil could shrink or collapse at a later date.
These have been in the news lately, but even the smaller ones can cause serious problems for homeowners. These are caused by the soluble rock layer just under topsoil being eroded by acidic water, forming a cavity just below the topsoil. The top soil then collapses into the space below. The water damage can be due to heavy rainfall or poor drainage systems. The collapsing soil then causes subsidence, which affects your building or home.
Subsidence can be caused by a huge variety of different things, both man made and natural, and it’s important to know so that you can plan your building development or home sale armed with information about it. Soil shrinkage and water damage may make up 90% of all subsidence cases, but that doesn’t mean it can’t be something else. Don’t get that sinking feeling, find out everything you need to about subsidence and make sure you’re prepared.