Subsidence is one of the most serious problems that homeowners can face. The consequences of subsidence can be disastrous for the safety of the property and can lead to some very expensive damage costs.
Knowing the signs of subsidence can help you feel more at ease and safer in your home. By knowing the signs, you will be able to spot potential damage and act fast to prevent further damage.
In this article, property and construction expert Natalie Mitchell at HomeHow.co.uk goes over everything you need to know about subsidence, including what it is, the signs to look out for, and how to prevent subsidence at your property.
What Is Subsidence?
Subsidence is a phenomenon that occurs when the ground underneath your property sinks. This then pulls the foundations of the property with it, affecting the structural integrity of the building. Subsidence usually occurs when the ground loses moisture, causing shrinkage. This is most commonly due to periods of dry weather or due to surrounding trees and shrubs. However, there are some other causes of subsidence, such as poor groundwork or nearby mining.
There are two main categories of substance. The first is historic movement, which means the subsidence has caused problems in the past but has since been stopped or repaired. The second is active movement, which means the subsidence is currently causing problems.
Historic subsidence is less of an issue than active subsidence. However, it can still affect the value of your property. Active subsidence can cause some problems now and will also greatly reduce the value of your property as well as the safety of the building.
Risk Factors That Can Increase Chances of Subsidence
There are certain risk factors that can increase the chances of experiencing subsidence at a property. These include the following:
- Drought – If you live in an area that is prone to drought, the soil could easily dry out, increasing the chances of subsidence.
- Nearby trees – If there are trees or shrubs that are planted too close to your property, these could drain the moisture from the soil, causing it to dry out and shrink.
- Clay – Clay soil goes through a lot of changes depending on the weather. When the weather is hot, clay soil can dry out, crack, and shift, making the ground unstable and making subsidence more likely.
- Age and construction – If you live in an older property, there may be a greater risk of subsidence since older properties tend to have shallower foundations.
- Leaks – If there are any leaking drains or leaking water mains at your property, this can soften the soil or wash it away, making subsidence more likely.
- Mining – If your house is close to a quarry or pit, it may become unstable as the material used to fill in the site can shift over time. Mining activities nearby can also be a risk factor.
- Poor groundwork – If your foundations are built correctly, this can cause subsidence issues.
What Are the Signs of Subsidence?
There are several signs of subsidence that you can look out for at your property. These include the following:
- Windows or doors sticking
- Cracks in the ceiling or walls
- Expansion of existing cracks
- Uneven floor surfaces
- External wall cracks
- Wallpaper crinkling at the ceiling/wall joints
If you have noticed cracks in your home, there are certain characteristics that you can look out for to determine whether these are subsidence cracks.
Firstly, look at the size of the cracks. Subsidence cracks are usually wider than 3mm and tend to be wider at the top than the bottom.
Next, look at the shape of the cracks. Subsidence cracks are usually diagonal.
Finally, look at the location of the cracks. Subsidence cracks usually appear close to windows or doorways.
A single crack in the wall is not always a sure sign of subsidence. Cracks can appear due to the walls and ceilings of your home shrinking and swelling over time due to changes in temperature. New homes or newly plastered homes can experience cracks due to the plaster drying out or due to the property settling into the foundations.
How to Fix and Prevent Subsidence Issues
If you think you have subsidence at your property, the first thing you’ll need to do is get in touch with your building insurer. The insurance company will then arrange for a structural engineer to come out and inspect your home. In some cases, the engineer may recommend that your home be monitored for several months so that they can determine if subsidence is the issue.
If your home is sinking due to trees, the best thing you can do is remove the tree. However, you should only do this after discussing the issues with a structural engineer and a tree surgeon. If you remove the tree in the wrong way, this could cause further damage to the property.
If leaking pipes is the issue, the best thing you can do is to get these issues fixed immediately. The property may then stabilise. However, you will need to monitor it to make sure the issues are not continuing.
To prevent subsidence, there are a couple of things you can do as a homeowner. Firstly, avoid planting trees and shrubs too close to the property. Secondly, make sure your pipework and plumbing are well maintained. Regularly inspect your plumbing for leaks.
What Is a Subsidence Survey?
You may want to find out if you have subsidence before contacting your insurer. If this is the case, you will need to arrange a subsidence survey with a qualified structural engineer. The engineer will attend to your property, look for subsidence signs, and will assess the extent of the subsidence problems.
The engineer will be able to determine if the visual signs are, in fact, due to subsidence or if these are just a result of normal building movement. This isn’t always obvious straight away, so the expert may need to monitor your property over a period of time.
Underpinning a Property
In the worst cases of subsidence, your property may need to be underpinned. This is a very large and disruptive job with very high costs. Underpinning is only used as a last resort, so it won’t always be necessary. To avoid this, it’s important that you get in touch with your insurance or a structural engineer as soon as you notice any signs of subsidence. The sooner it is identified, the easier it will be to rectify.
