When do you need to address cracks and foundation problems?

Aug 1, 2021 | Building Issues

Did you know that all buildings move? Not enough that you would necessarily notice, but enough that over time they can cause issues you might not have anticipated.

I bet you didn’t know that, most people don’t. However, it is something you need to be aware of as it can be costly if cracks being to appear in your walls or ceilings or if you start to see your doors dropping.

Subsidence can cause major problems for a property, but if caught early can be corrected. Movement of a building and its foundations due to the earth moving beneath, can cause damage to the main structure, brickwork, and windows. Our team at Eyesurvey can assess your property for potential subsidence, and discuss the options available to you.

In addition to being unsightly, cracks can signify major property damage, raising questions about safety as well as stability and integrity if they affect important building components. A structure must considerably deteriorate before it becomes prone to collapse, but fractures and other signs of degradation should never be disregarded.

In order to rectify these potentially devastating problems, you need to find the cause – what is creating the cracks in the first place? From there, a strategy can be formed in order to diagnose and then to fix the issues and ensure it’s not an ongoing problem for years to come.

Where do cracks come from?

Unfortunately, there isn’t one reason for a crack or building movement meaning there isn’t an easy fix, there can be multiple reasons and no one-size-fits-all approach.


Whether it’s damaged drains, leaks from faulty pipes, misplaced moisture is no one’s friend in the home. It can cause walls to expand, meaning cracks can form internally and entire walls will need to be replace. Moisture can allow wood decay to develop, also lead to mould which is a problem in itself if it gets out of control.


Heat can have a major impact on buildings and can cause materials to contract and expand depending on how hot it is. The position of a wall relative to the hot sun will lead to significant expansion, and as the wall is effectively part of a box and can’t move away, it may buckle and crack. The NHBC actually require expansion joints to be installed during construction, to avoid such problems.

Foundation erosion

The foundations of a property can begin to erode over time and through issues with the materials used or interference, such as chemicals, can begin to suffer problems. In the past, using contaminated sand from a seafront beach without washing it led to serious deterioration, then failure, of the concrete into which it had been added.

Ground movement

The ground beneath the foundations can experience issues due to land slip, heave (see my article on this from last year in the news section), and shrinkage, among other things. Adding an extension can be a cause, since the differing building standards often produce defects after a shortish period; the deeper foundations of the extension compared to the house make that extension less able to move with the seasons.

Building fabric

A buildings fabric (aka. the structural materials that make up the shell) of the property, can be susceptible to material breakdowns including rust and rot. Excess damp is often involved.

Property age

If you have an older property, it is worth noting that they are generally built on shallower foundations, resulting in more movement than their modern counterparts. However, earlier building materials and methods are likely to compensate, and defects may not occur.

Did you know that bricks laid in lime-based mortar may crack along the joints from movement, but the lime will chemically adjust and take up the cracks, a form of “self-healing”?

Other issues

other problems occur with structural defects, suspended floors, and outside interference such as encroaching or penetrating tree roots. As a rule of thumb, the root spread of a tree averages two-thirds of its height, dependant on the species.

When cracks are a worry?

It’s important to note that some cracks – such as fine internal ones – aren’t going to cause issues with your property and can be rectified with some decoration and filler.

However, cracks that are over 1.5mm wide, or several centimetres long do require your attention; and anything that’s 2mm – 3mm or more in width could be extensive damage, affecting the windows, door frames and walls. If there are protruding areas or you notice a distortion around the door or window frames, these would need to be addressed quickly.

Any cracks over 4mm – 5mm and above in width, or developing quickly, would be classed as significant structural damage and would likely mean substantial repairs were necessary. You will not want to find your property to be unstable and that the work carried out to fix it would be more in-depth. These could also cause safety and integrity situations that would be of a high-priority to rectify.

What are signs of building movement?

Cracks in the exterior of your property would be the first indication of a problem with the foundations. The foundation can shift, allowing gaps to appear due to the general building movement, and while it is normal for a foundation to sink very slightly over the space of the early few years in the life of a building, exterior cracks in the brick are normally a bad sign.

Cracks aren’t the only signs that you have problems with the structure of your property. If you’re living in your property for a long period of time and you start to notice your property sinking on one side, this is something that should be immediately looked into. If doors begin to jam or won’t close correctly, it can be costly to let this problem develop and can become a stability and safety issue.
Doors and windows sticking lately and you don’t think it’s the weather? Interior doors that have dropped and are dragging, and can no longer close properly, can be a sign of a foundation issue too. Similarly, if your windows have dropped and have gaps around them it’s best to get them checked out by a professional.

Examine your kitchen, is there anything in the back of the cabinets or on the floor that wasn’t there a few months ago, gaps for example to indicate movement? Or are the cabinets and wall units aligned and parallel to the wall? This might indicate that something is happening beneath your feet, possibly part of your home’s foundations. This is not something to overlook, since the condition may worsen, resulting in a larger repair cost.

One of the biggest areas to keep an eye on is your floor! Foundation issues from building movement can impact the foundation and in turn make the floor sag or bow. Not only conventional timber floors, but concrete/ solid floors may also develop problems such as in 1960 – 1970s properties. If your floors appear to be uneven this can impact the safety of children and any vulnerable relatives, so be aware of this and see the issue gets fixed.

Now for an example of how cracks that are serious don’t just occur in your house, but may then begin to affect it. Some time ago, we were asked to advise on a boundary wall near to some flats all on a fairly steep slope. Cracks over an inch/25mm wide and several feet/metres long had developed within a few months, and the wall looked near collapse. Worryingly the block of flats was less than 10 feet/3 metres from the worst cracks.

After a bit of research following the inspection itself, we learned the neighbouring house owner had decided to level out his sloping garden. He had the the bank sloping upwards towards the flats excavated, so the small part of the bank remaining was even steeper, and was smaller, and weaker.

Unfortunately, that meant that the former bank that had been giving support to the boundary wall was no longer there, and the foundations of the flats adjoining, so the support had gone. The wall then cracked quickly. If we hadn’t found out and reported the reasons, the block of flats might have started to crack and move as well. All was put right and rectified in time.

Remember, it’s always cheaper to pay to have a professional surveyor say there’s nothing seriously wrong, than to let the hairline crack become a nightmare.


Les Long FRICS FISVA Principal, Eyesurvey

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