Many people wonder if subsidence can occur on a patio, and it’s for a fair reason. Subsidence is among the severe yet not uncommon threats to any construction.
As this phenomenon poses tremendous safety risks and damage to the house, learning to prevent it is critical. Therefore, can a patio cause subsidence?
In this post, I will provide a simple answer and additional helpful measures to protect your patio better. Follow the sections below to learn more!
Table of Contents
What Is Subsidence? Why Is It Dangerous?
Subsidence generally occurs when the ground beneath your housing property starts to sink.
It means that the ground will level down in one part or entirely and cause an unbalanced surface.
So, the house’s floors and walls will move on the groundwork and break their structures.
The consequences are destabilization and cracks in your house. In severe cases, subsidence can break down a whole large construction.
However, subsidence is different from other common ground moving threats like landslip, settlements, or heave.
Now let’s move to the question: is subsidence possible on a paver construction?
Can A Patio Cause Subsidence?
The answer is yes. Subsidence can occur on a paver construction and similar impermeable surfaces like a concrete driveway.
Unlike brick paving, these constructions allow water to get in and potentially lead to subsidence.
Research conducted by the BGS (British Geological Survey) indicates that the rainfall can run into the drains of driveways and patios. The water permeates directly into the drains rather than flower beds and lawns on the side.
As a result, the tree roots don’t have direct access to water and have to stretch out searching for water. This phenomenon (the movements of tree roots) will underpin the foundation and cause an unbalanced soil’s moisture.
Meanwhile, most homeowners living on the side of streets often construct a parking area on their property. These houses always have a large tree nearby on the road or in the garden.
For this reason, the risk of subsidence will increase substantially due to the movement of that large tree’s roots in search of water. Therefore, you should be careful about the large tree nearby.
It may sound peculiar, but the best method to prevent this phenomenon is to ensure that the nearby tree always gets enough water. You can notice that the clay soil around large street trees is often prone to subsidence.
The key to why a patio can cause subsidence is that its surface is waterproof. So, the water cannot go through the patio’s surface and get to the tree roots.
Trees always need water, and they will move their roots around in the clay soil searching. All these conditions will lead to subsidence on your property.
What Causes Subsidence?
As explained above, if there is a large street tree near your property, its roots’ movement can shift the clay soil beneath the foundation and lead to subsidence.
However, the primary reason why tree roots move is to search for water, and this is when the patio gets into play.
If your paver features a brick paving surface, the rainfall can get through the small cracks and permeate into the soil.
As a result, the tree can get access to water without the need to move its root.
You don’t have to worry much about subsidence from brick pavings, given that the area gets frequent rains.
Most patios feature impermeable surfaces from concrete, crushed stone, and sand. So, water cannot permeate through these surfaces to the tree’s roots.
Therefore, the tree doesn’t get enough moisture, and it has to move the roots to search for rainfall in the area.
Meanwhile, the clay soil is very prone to subsidence and cracking, especially in the summer months with a dry climate.
This phenomenon can be called soil “desiccating.” The final result of this movement is subsidence and foundation shifting.
How To Spot Subsidence?
If you notice the sloping or sink floor, the area may be under the effect of subsidence. This sign indicates that the property’s foundation is collapsing, and you need to get it checked as soon as possible.
Also, check every corner of your house, including the walls, doors, windows, and driveways. Notice the position of any cracks that run in a diagonal pattern.
Measure if the crack’s diameter surpasses 3 mm. These are the common signs of subsidence from medium to severe levels. If you can put your little finger into the crack, it’s more than alarming.
Check if you can see the cracks from both indoors and outdoors. Normally, cracks caused by the degradation of the wall’s materials can only be seen from one side. If you can see it from both sides, the wall has been thoroughly shaken.
Then, move on to check the walls and corners for any visible gaps (skirting boards) between them. Another subtle sign is the puddles’ formation around the property’s perimeter.
How To Prevent Subsidence?
Prevention should always be the priority since it costs a lot of effort and money to deal with subsidence’s consequences. I know that a garden filled with large trees will make your house much more beautiful.
However, you’ll have to ensure that the trees get enough water and moisture, especially in the dry summer months.
If your patio’s surface is not permissible, you should water the trees regularly.
Also, keep the soil from getting undersaturated. If you love planting trees, they are planted far from your properties (maybe in the corner of the garden).
Don’t forget to check your property once a month for any signs of subsidence mentioned above. It gives you the time to fix the problem when severe consequences haven’t happened.
How To Fix Subsidence?
The first thing to do is contact the insurer of your property, so he can carry out a full assessment of the subsidence’s damage.
Then, you are left with two solutions: resin injections and underpinning.
I would recommend resin injections as the priority if the subsidence is not likely to reoccur in the future.
The resin is injected down the ground and filled into the gaps, just making your house’s foundation stronger.
FAQs
Here is some additional information that will help you discover more about subsidence and learn to prevent it better. Follow the sections below to find out!
How Common Is Subsidence?
Subsidence occurs more frequently than you thought. In fact, it’s one of the most prevalent structural problems.
According to the British Geological Survey (BGS), this phenomenon can even occur on new constructions and surfaces.
BGS also estimates that around 7% of the total properties in Greater London are at risk of subsidence, which is an alarming number.
Is Movement The Same As Subsidence?
Subsidence and movement can sometimes be used interchangeably.
These two terms both indicate the subsidence of shifting of a construction’s foundation, leading to damage and cracking on the structure above it.
Yet, movement can sometimes refer to landslides or heaves, while subsidence differs from these phenomena.
How Do I Find Out If I Have Subsidence In My Area?
Cracks on the walls and floors are one of the most alarming sights of subsidence. You can observe the crack to know if it’s the consequence of subsidence.
- The crack is thicker than 3mm, and its thickness gradually increases.
- The crack runs diagonally on the floor and across the wall.
- The crack’s top is wider than its bottom.
- You can see it clearly from inside and outside of the property.
- It runs near the windows and doors.
What Are The First Signs Of Subsidence?
As mentioned above, wide cracks on walls and floors are the most apparent sights of subsidence, especially the ones running near the windows or doors.
Another alarming sight is the sticking doors and windows. Also, don’t ignore the sloping floors, which is a common result of subsidence.
Does Subsidence Always Need Underpinning?
You don’t have to use underpinning to deal with the subsidence issues. It should only be viewed as a last resort since many other more effective solutions exist.
In addition, underpinning is not necessary if subsidence isn’t likely to reoccur or when the damage didn’t impair or obstruct the house construction integrity.
Final Thoughts
Can a patio cause subsidence? In summary, a patio can cause subsidence when it features an impermeable surface like a concrete driveway.
This construction still allows water to pass through and cause the ground and inner structure to sink. Therefore, you should implement protective measures to protect your patio from subsidence if it has these features.
I hope that the answer provided can satisfy you. Thank you for reading the post!
Related Posts: