Subsidence is a word that no homeowner wants to hear. Whether you’ve had a prospective home surveyed, looking to sell your house or have resided at your property for many years, subsidence is something you hope you never have to deal with.
However, subsidence does occur and it can be a severe problem, hence why no time can be wasted when having it looked at and then rectified. But there’s a very specific, innovative method that’s used to treat subsidence and that service can be delivered by Geobear.
But before you choose to have subsidence treated, you must first understand what subsidence is, what to look for if you suspect subsidence might be occurring, and what might be causing the problem.
What is subsidence damage?
Subsidence occurs when the ground beneath a structure or building starts to sink or collapse, resulting in movement of the existing foundations. Often, only one side of the property will sink, which will then cause cracks to appear both internally and externally, making the problem obvious to the property owner.
Damage caused by subsidence shouldn’t be confused with ground heave, as this is where the ground moves upwards as opposed to downwards as a result of clay swelling. This issue should be addressed using a different method to that which rectifies subsidence. Both are serious.
Is subsidence common?
Yes, it is a relatively common issue, and despite its commonality, it can be serious. Several factors make subsidence more likely, including environmental factors, type of soil, tree roots and foliage growth, and structural issues with the building.
For example, it’s estimated that due to the clay soil type in London and the southeast, up to 1 in 50 houses suffer from subsidence.
Is subsidence dangerous?
Not directly or in the short term. However, because it leads to disturbance of the building’s structure, this will have a long-term, knock on effect upon utilities, brickwork and other features of the property. In severe cases, it may lead to serious cracks in the walls and even to parts of the property collapsing. In the rare cases where subsidence goes unchecked, it will eventually become dangerous.
Does a level 2 survey check for subsidence – or do you need level 3?
Thankfully yes. Unlike other hidden problems, any major subsidence will be clear to an experienced surveyor. For example, cracks on external walls, pooling around the property, loose skirting and jamming doors are all fairly obvious.
However, it may be missed where the conditions exist for subsidence to happen soon, but it hasn’t happened yet, or is only minor. A level 2 survey may not uncover the more subtle damage or signs of subsidence, so you could play it safe with a level 3 survey for extra peace of mind.
How to spot subsidence in your property
Several signs of subsidence will make themselves apparent throughout both the inside and the outside of your home. Often, they’re relatively obvious to spot, so if you find one or more of the following signs, then you should have the problem seen as soon as possible.
- Sinking or uneven floors and ceilings
This indicates that the ground beneath your home is sinking or collapsing. Depending on the severity of the slope or how far the floor has sunk, it can be rectified using the correct method. Although, you must not let it get to the point where the house could actually collapse.
Do not ignore sinking or sloping floors and ceilings as this is often one of the very first things that’ll happen if subsidence is occurring.
- Cracks in walls, garden paths and driveways
Cracks within walls are a common sign of subsidence, but this can also occur for other reasons – so what do subsidence cracks look like?
On the external walls, cracks will often appear in a zig-zag pattern, following the mortar lines in the brickwork – in some instances the bricks will also crack. Subsidence cracks, whether found internally or externally, are usually big enough to fit a coin into. This is much more significant than minor crack which are seen in the overlaying plaster.
It’s important to note, however, that hairline cracks inside the home is generally a normal phenomenon and nothing to worry about. But if they come along with any of the other signs in this list, then you should call out a professional to inspect the problem, just in case.
- Windows or doors that are jammed or misaligned
Subsidence will cause all manner of problems around joins with regards to window and door fittings. Often, this can make them both hard to open and/or close – something else to look out for if you suspect your house is falling victim to subsidence.
However, it’s important to note that door and window stiffness can occur for other reasons. For example, the hinges may simply be old, worn and sagging.
- Skirting boards are coming away from the wall
If subsidence occurs, then you’ll start to notice significant gaps between the skirting board and the wall to which they’re fixed. Where it can often be mistaken for being warped, especially if your skirting boards are wooden, it’s likely to be the former as opposed to the latter, unless there’s excess moisture in that particular area. Even so, you should have the house checked for subsidence, just to be on the safe side.
- Puddles forming around the perimeter of the property
This can indicate a problem with the drainage system, but that also poses problems to the property’s foundations. Pooling or excess water can cause the soil to soften and destabilise, causing the foundations to shift.
As the ground dries, it’ll then shrink, which could escalate the problem. If you spot this sign, you should get it looked at as soon as possible.
What causes subsidence?
Although it can be hard to pinpoint exactly what is causing your home to subside, the professional who comes out to your home will have an idea as to what the problem could be. Some subsidence risks include:
- Excessive moisture – An excessive amount of moisture in the ground or pooling around the property may lead to subsidence damage.
- Clay soil – This type of soil beneath your property can shrink, crack and shift in the summer heat, especially in the southeast of England.
- Parched ground – If the area you live in is prone to dry weather, this can be common cause of subsidence. The drier the ground is, the more likely it is that cracks may appear in your walls because as the ground dries out, it shrinks and contracts.
- Trees & shrubs – Trees and shrubs located near the property absorb water from the ground beneath, therefore causing it to dry out. The intrusion of roots into the fabric or foundations of the building is equally a concern.
- Leaking drains or water pipes – These will soften the surrounding ground. This could then cause the ground to compress and eventually sink under the weight of the house, especially if drainage solutions are not dealt with.
- Mining areas—Former coal mining regions may experience subsidence due to old mine shafts and ground disturbance. This issue is common in certain parts of the Midlands, Yorkshire, and the North East.
Can you get a mortgage or insurance on a house with subsidence?
It is possible, but considerably harder. Subsidence presents a major risk to lenders, so they may charge you a higher deposit or request that it be fixed before you buy. At the same time, the number of lenders willing to offer you a mortgage will be drastically reduced because many banks simply do not want to take on the risk.
Sometimes lenders will be more lenient if you can present a certificate which confirms the problem is fixed, or if the subsistence is shown to have stopped entirely (for example, if problematic vegetation has been removed or drainage systems fixed).
Similar principles apply if you are trying to get home insurance for a property with subsidence. Fewer insurers are willing to offer you a policy, and when they do, these are more expensive and include higher premiums. Go Compare estimates that the average policy cost for subsidence insurance is over £500 per year with an excess often above £2500. You will need to inform you insurance company clearly about the extent of the problem, too.
Strategies to treat & prevent minor subsidence
Before major damage occurs, there are several ways to control or minimise the damage of subsidence. Sometime these can be used as temporary measures before more serious solutions are used.
Controlling trees & vegetation
Sometimes subsidence can be controlled or prevented by removing vegetation. This is especially the case where large trees are draining moisture from clay soil surrounding the property.
Even so, you will need to get expert advice before making the decision, because sudden extraction of trees can lead to even less structural stability in the short term.
Fixing drainage problems
Since blocked or leaking drains can wash away soil and destabilise the ground, you may need to address these systems. For example, repairing or replacing defective drains, installing soakaways, or redirecting water flow as a means to stabilise the foundations.
Crack stitching & wall ties
Minor cracks in brickwork can be addressed with the insertion of steel bars or injecting epoxy resin. Equally, cavity wall ties can be used to strengthen walls which are affected by subsidence.
How to repair subsidence (when it is major)
There are two main ways to fix major subsidence, often in conjunction with the controlling and preventative measures mentioned above.
Underpinning for subsidence
This is the most well-known solution to fix major subsidence. It can be exceptionally expensive, highly intrusive and logistically challenging to do. Checkatrade estimates that mass concrete underpinning costs an average of £13,500 per wall.
So, what is underpinning? It’s a procedure which involves stabilising the foundations of the property by strategically digging holes beneath the foundations, and then filling them in with concrete. The beam and base method adds a load-bearing beam for extra support, and ‘piling’ is used where exceptionally deep foundations are involved.
The cost and labour involved is why many people run for the hills when the word ‘subsidence’ comes up on their home survey. So, can subsidence be fixed without underpinning?
Resin injection for subsidence
Geo-polymer resin injections are an increasingly popular way to address subsidence. These eliminate subsidence efficiently, with far less labour, far less cost and impressive results. The method involves injecting an expanding resin into key points of the ground, which then fills vulnerable gaps in the building’s foundation.
So how does it work?
Firstly, engineers drill a 16mm hole into the ground beneath the property to reach the areas of subsidence (without having to gain access internally). Secondly, a geopolymer resin, which will expand within the soil and rapidly harden, is injected into the affected ground. The resin cures almost immediately making it an efficient, effective and lasting solution.
In some instances, you’ll see cracks disappear around the home as the resin expands and lifts the property’s foundations upwards. It’s also possible to notice that windows and doors that were once jammed or difficult to open return to full functionality.
Feel you know how to fix subsidence?
We hope you’ve now got a clearer idea of how to address subsidence problems, whether you require smaller fixes – or a resin injection solution for your whole foundation.
