Significant foundation movement can be a sign of structural damage which can be costly to repair. If you’re concerned about foundation movement, you need to know how much movement is acceptable and how much is cause for concern.
Most building codes define acceptable foundation movements in millimetres over a specific period. For a residential building, an acceptable foundation movement is less than 25 mm over 12 months. Lateral movement (from side to side) should not exceed 6 mm.
Read on for a more detailed explanation of acceptable foundation movement, the causes and the warning signs to look for.
Jump to section:
- How Much Foundation Movement Is Too Much?
- What Causes Foundation Movement?
- What Are the Signs of Excessive Foundation Movement?
- When Should I Be Worried About Foundation Cracks?
- Structural Surveys in London by Crest Surveyors
- Foundation Movement FAQs
How Much Foundation Movement Is Too Much?
Although some foundation movement is considered normal, excessive movement can compromise the building’s structural integrity and have disastrous long-term consequences. Most building regulations define acceptable foundation movement for a residential structure as a maximum of 25 mm over 12 months. Lateral movement (from side to side) should not exceed 6 mm.
However, the acceptable level of foundation movement can vary based on soil type, the building’s design and local building codes. For example, a single-story building, such as a bungalow, can typically tolerate a higher level of movement than a multi-story building.
If you’re concerned about foundation movement in your property or a building you’re purchasing, it is essential to book a building defect survey to assess the problem. If you want the most comprehensive survey, a full structural survey might be the better option. Have a look at our blog, ‘What Is Looked at in a Full Structural Survey?’, for more information about what is included.
What Causes Foundation Movement?
There are a range of issues which can result in foundation movement. Here is an overview of the most common causes.
Poor Drainage
If your property has insufficient drainage, the added moisture saturates the soil making it expand. This causes uneven support and puts pressure on the foundation walls causing movement. Poor drainage can be caused by blocked gutters, damaged roofs, negative slopes and standing water.
Tree Roots and Plants
Invasive tree roots can also cause foundations to shift over time. Other plants, such as Japanese Knotweed, can also cause significant structural issues.
Environmental Changes
Extreme weather conditions can also damage foundations, although this is rare. Heavy rain can cause soil to swell, while drought causes the soil to shrink. This can cause the foundation to shift and impact the property’s structure.
Soil Type
Soil type and composition can impact the long-term stability of foundations. Clay soil can change significantly in volume as the moisture content changes, which can lead to foundation movement if it has not been accounted for during construction
Negligent Construction
If low-quality materials have been used during construction or the foundation has been laid incorrectly, this can result in foundation movement and significant damage that is costly to repair. If you’re thinking of buying a property, a RICS Homebuyer Survey is essential to assess the condition of the building.
What Are the Signs of Excessive Foundation Movement?
There are several signs of excessive foundation movement that you should look out for when viewing a property or if you’re concerned about your building’s foundations.
These signs include:
- Sudden cracks on interior and exterior walls, floors, tiles or ceilings.
- Doors and windows which stick or don’t function properly.
- A visible lean or tilt of the building or a leaning chimney.
- Bending walls or gaps appear between the wall and the floor or ceiling.
- Creaking or cracking sounds.
- Rot or dampness issues.
When Should I Be Worried About Foundation Cracks?
One of the most common signs of foundation movement is cracks. However, it can be difficult to tell the difference between harmless cracks as a result of normal settling and cracks which indicate structural damage and a shifting foundation.
If you notice the following in your property or the property you’re purchasing, you should book a building survey by a registered surveyor:
- Large cracks that are wider than 4mm
- Cracks which are wider at one end
- Cracks that get bigger over time
- Horizontal cracks in foundation slabs
- Significant diagonal cracks
- Stairstep cracks in brick walls
- Cracks that go across the ceiling and down a wall
- Several cracks grouped together
Structural Surveys in London by Crest Surveyors
If you are concerned about foundation movement in your property or a building that you are purchasing, you must get this looked at as soon as possible. The RICS-qualified Chartered Surveyors at Crest are here to help.
A building survey is the most suitable option if you need to diagnose defects, damages, and potential issues with a property, including foundation movement and structural damage. Crest Surveyors offers comprehensive RICS Building Surveys in London and the South East of England.
To learn more about what’s included in our building survey or speak to one of our experts about your foundation movement issues, get in touch with us today. Call us on 020 3940 1118 or fill out our contact form.
Foundation Movement FAQs
What Is Foundation Movement?
A foundation or structural movement is when a property moves away from its original foundations. Any issues with a property’s foundations must be identified and rectified quickly to ensure the building is safe and structurally sound. Any foundation movement can be identified by a RICS-qualified surveyor using a Building Survey.
How Much Foundation Settling Is Normal?
A small amount of settling in the first few years after a home is built is normal. Thin hairline cracks may appear. However, it’s still essential to be vigilant and monitor any cracks to ensure there are no structural problems.
Non-structural cracks should be vertical and 5-15 cm long. Wider cracks, longer cracks or any diagonal or horizontal cracks could be a sign that something is wrong with the foundation and you should seek professional help.