In this blog post we are going to take a more in depth look at subsidence and try to answer the questions posed in the title of the article. We’ll also try and give some pointers on how to spot subsidence which can be very useful if you are considering buying a property.
If you are considering making a property purchase you should always have a structural survey done, in fact if you are using a mortgage to buy the property lenders will insist on it. This type of report will let you know if your prospective purchase is structurally sound or whether there is any structural movement or subsidence. This will help save you from making what could be a very expensive mistake.
What Is Subsidence?
Subsidence occurs when the ground sinks or settles below a property which then causes the foundations to collapse. When the soil underneath a property starts to weaken or lose volume the foundations will start to shift causing them to collapse and sink to a point where they are unable to support the building, which in turn puts its stability and structural integrity at risk.
What Are The Main Causes Of Subsidence
There are a number of reasons why subsidence happens and some of the main ones are:
Soil Type: If your home is built on clay then there is a greater chance that it will suffer from subsidence. This is because soil that is rich in clay dries out more in hot weather which could lead to it shrinking and detaching itself from the foundations which in turn weakens the support they provide. Soil that contains a high level of sand or gravel could also put your home at risk as it could wash away easily if there are any leaks on your property.
Tree Roots: Possibly the most common cause of subsidence, tree roots that are located in close proximity to your property take moisture from the soil underneath the property which dries out the soil and causes it to shrink. When this happens the ground below your home will become destabilised putting it at risk of subsidence. If you have tree roots growing close to your home the best thing to do is remove them as soon as possible.
The Weather: If you live in a climate that experiences extreme weather conditions it can put your home at risk of subsidence. The make up of soil means that it will expand during wet weather and contract during dry conditions. If you experience prolonged periods of wet weather in the winter followed by hot dry summers it may lead to constant fluctuations in groundwater levels, which could well destabilise the soil beneath your home.
If your property is located in an area prone to droughts it could be at risk of subsidence due to the soil shrinking. Conversely if you live in an area that experiences floods subsidence can occur when soil becomes saturated and the excess water washes away foundations.
Drainage Leaks: Leaking drains and gutters can also cause subsidence. If water escapes from your pipework into the soil below your home it could wash away the soil foundations especially if your property is built on soil with a high concentration of sand and gravel. When water leaks from your drains the ground can become saturated which can lead to the foundations giving way and subsiding.
Mining: Properties built in areas that were once used for mining or quarrying are particularly vulnerable to subsidence. Building on land previously mined results in weaker and less stable foundations, as underground voids can cause the ground to sink over time.
What Are The Signs Of Subsidence
There are a number of telltale signs that your property or one that you are thinking about buying has subsidence which include:
Cracks in walls: Especially if they are located around doors and windows, are wider than 3mm, appear wider at the top than the bottom, spread diagonally and may widen over time. Fortunately the majority of cracks are purely cosmetic but some are signs of subsidence and should be treated seriously.
Sticking doors and windows; If doors or windows are difficult to open or close this may indicate the structure has shifted as a result of subsidence.
Sloping or Uneven floors – if a property has sloping floors or gaps in between the skirting boards and the floor it could highlight the presence of subsidence.
Gaps forming between walls and extension joints: When a house has subsidence it is likely that you will see gaps start to form where extensions or conservatories meet the main building.
Cracks in external brickwork – If cracks are visible cracks on the outside wall of the property, especially in the brickwork, this is another sign that you may have a problem with subsidence.
What Can You Do To Prevent Subsidence?
If you want to prevent subsidence occurring you need to make sure the ground around your property remains stable. One way to do this is keeping control of the water levels in your soil. Make sure any large trees or shrubs close to your home are either pruned on a regular basis or removed to prevent the roots absorbing moisture. Make sure you don’t plant water-hungry trees like willows too close to your property.
Keep your drainage system well maintained and make sure you deal with any blockages or damage immediately. This will prevent water from pooling around the foundations, which could weaken the soil. During dry periods of dry weather make sure you water the soil as this will reduce the risk of excessive shrinking. Regular property maintenance, including fixing leaks promptly and cleaning your gutters regularly also plays a key role in reducing the risk of subsidence.
How Can Piling Help Prevent Subsidence
The deep and stable foundations provided by piling will keep you well protected against subsidence. The long steel or concrete piles driven into the ground provide all different kinds of property with a solid foundation.
Using piling ensures that the weight of the structure is supported by the strong layers below, bypassing weaker or shifting soil near the surface. Piling is especially useful in areas prone to ground movement or where the soil is unstable, such as former mining sites. By reinforcing the foundation, piling reduces the risk of subsidence and long-term structural damage.
We hope that the information provided in this blog post has given you a greater insight into the causes of subsidence and the best ways to prevent it. If you would like to find out how traditional piling or mini piling can help provide properties with a stable foundation and remove the possibility of subsidence, call the team here at WL Piling without delay.
