Cracks in your home can be worrying, especially if they’re caused by subsidence. These splits often appear when the ground beneath your house moves or sinks.
Subsidence treatments include fixing leaky pipes, removing problematic trees, and injecting resin into the ground.
Spotting subsidence early is key. Look for wide, diagonal cracks, mainly around doors and windows. These cracks might get bigger over time.
If you see them, don’t panic. Many homes with subsidence don’t need major work.
To fix subsidence cracks, start by getting a expert to check your home. They’ll look at the cracks and the area around your house.
Based on what they find, they’ll suggest the best way to fix the problem. This might involve simple repairs or more complex solutions.
Key Takeaways
- Check for wide, diagonal cracks around doors and windows
- Get a expert to assess your home if you spot signs of subsidence
- Fix leaky pipes and manage nearby trees to prevent subsidence
Understanding Subsidence
Subsidence can lead to serious damage in buildings. It occurs when the ground beneath a structure sinks or shifts. This movement can cause cracks in walls, floors, and foundations.
Causes of Subsidence
Several factors can trigger subsidence:
- Soil shrinkage: Clay soils shrink when dry, causing the ground to sink.
- Tree roots: Large trees near buildings can suck moisture from the soil.
- Leaking pipes: Water from damaged pipes can wash away soil.
- Mining: Old mine workings can collapse, leading to ground movement.
Natural events like earthquakes or landslides can also cause subsidence. In urban areas, nearby construction work might disturb the ground under your home.
Signs and Symptoms
Spotting subsidence early is key. Look out for these warning signs:
- Cracks in walls, especially near doors and windows
- Doors and windows that stick or won’t close properly
- Sloping or uneven floors
- Gaps between walls and skirting boards
Diagonal cracks wider than 3mm are often a sign of subsidence. They tend to be wider at the top than at the bottom. Keep an eye on any cracks that appear suddenly or grow quickly.
Types of Subsidence Cracks
Not all cracks mean your house is sinking. Here are different types to watch for:
- Hairline cracks: Very thin and often harmless
- Minor cracks: Up to 5mm wide, may need monitoring
- Moderate cracks: 5-15mm wide, could be a sign of subsidence
- Severe cracks: Over 15mm wide, likely due to serious structural issues
Vertical cracks are often less worrying than diagonal ones. If you see step-like cracks in brickwork, this could point to subsidence.
Impact of Soil Types
The soil under your home plays a big role in subsidence risk:
- Clay soil: Shrinks when dry, swells when wet
- Sandy or gravelly soil: Can be washed away by water
- Peat soil: Very unstable and prone to shrinkage
Homes built on clay are at higher risk of subsidence. This is because clay soils change volume a lot with moisture levels. If you live in an area with clay soil, it’s wise to keep an eye out for signs of movement in your home.
Initial Assessment and Monitoring
Spotting subsidence cracks early and tracking their progress is key to proper repairs. A careful inspection and ongoing monitoring help determine the best course of action.
Professional Inspection
A qualified structural engineer should examine your property for signs of subsidence. They’ll look for cracks around windows and doors, which are common trouble spots. The expert will check both inside and outside the building.
Key things they’ll note:
- Crack width and direction
- Wall bulging or leaning
- Stuck doors or windows
- Uneven floors
The inspector might dig test pits to check soil conditions. They could also use special tools to measure crack movement over time.
Monitoring Crack Development
Once cracks are found, it’s vital to keep an eye on them. This helps work out if the problem is getting worse.
Simple ways to track changes:
- Take clear photos regularly
- Measure crack width with a ruler
- Mark the end of cracks with pencil
For more precise tracking, pros use tools like:
- Tell-tale devices
- Electronic crack monitors
Experts often watch cracks for 12-18 months before deciding on repairs. This shows if movement is ongoing or has stopped.
Keep a log of any changes you spot. Note dates and measurements. This info helps decide the best fix for your subsidence issue.
Repair Techniques
Fixing subsidence cracks requires different methods based on the severity and cause of the problem. The right approach can stop further damage and restore structural integrity.
Minor Crack Repairs
For small cracks under 5mm wide, simple repairs often work well. Start by cleaning the crack and removing loose bits.
Fill the gap with a flexible filler made for masonry. This lets the crack move slightly without reopening.
For slightly bigger cracks, you might need to widen them first. Use a chisel to make a V-shape along the crack. Then fill it with a strong repair mortar. Smooth it out to match the wall surface.
Keep an eye on repaired cracks. If they come back quickly, it could mean a bigger problem. You might need a structural engineer to check for more serious issues.
Underpinning
When subsidence causes major structural problems, underpinning is often needed. This method strengthens the building’s foundation.
The most common type is mass concrete underpinning. Workers dig out sections under the old foundation. They fill these with concrete to make a deeper, stronger base.
Newer methods like resin injection can work too. Holes are drilled into the ground near the foundation. A special expanding resin is pumped in. It fills gaps in the soil and lifts the building slightly.
Underpinning is complex and costly. It costs about £400 to £1,000 per square metre, depending on the method. Always use experts for this job, but there are alternatives to underpinning available.
Helical Bar Reinforcement
This technique helps fix cracks in brick or stone walls. It uses twisted metal bars to hold the wall together.
Workers cut slots in the mortar joints across the crack. They clean out the slots and fill them with strong mortar. Then they push in the helical bars.
The bars grip the mortar and spread the load across the wall. This stops the crack from getting worse. It’s good for walls that have moved apart slightly.
Helical bars work well with other methods. You might use them after underpinning to repair the visible damage.
Expansive Grout
For subsidence caused by soil shrinkage, expansive grout can help. It’s a special mix that swells up when it sets.
Holes are drilled into the ground around the affected area. The grout is pumped in under pressure. As it expands, it fills gaps in the soil and lifts the building slightly.
This method works best for clay soils that have dried out. It’s less disruptive than traditional underpinning. But it’s not suitable for all types of subsidence.
The grout can lift a building by small amounts, usually up to 5mm. It’s often used with other repair methods for the best results.
Preventative Measures
Taking steps to prevent subsidence can save you time, money and stress. Here are some key actions you can take to protect your property.
Landscaping Adjustments
Proper landscaping plays a big role in avoiding subsidence. Plant trees and large shrubs at least 10 metres away from your home. This stops roots from sucking moisture from the soil near your foundations.
If you have existing trees close to your house, think about removing them or pruning them regularly. This limits their water intake. For new plantings, pick species with small root systems.
You should also keep flower beds away from your walls. The soil in beds dries out faster, which can lead to foundation movement.
Improving Drainage Systems
Good drainage is vital for preventing subsidence. Make sure your gutters and downpipes are clear and working well. Fix any leaks quickly.
Add soakaways or French drains to direct water away from your home’s foundations. These systems help spread water evenly through the soil.
Check for and fix any leaks in underground pipes. Even small leaks can wash away soil over time. Have a plumber inspect your pipes every few years.
Soil Stabilisation
In areas prone to subsidence, you might need to stabilise the soil. One method is to inject a special resin into the ground. This fills gaps and stops soil movement.
Another option is to add a layer of gravel or hardcore around your home’s perimeter. This helps keep moisture levels steady in the soil.
For clay soils, which shrink and swell a lot, you can add lime. This makes the soil more stable. But get expert advice before trying this, as it’s not right for all situations.
Regular soil tests can help you spot problems early. If you notice changes in your soil, act quickly to prevent damage.
Regulatory and Legal Considerations
Fixing subsidence cracks involves several legal and regulatory steps. These include getting the right permits, dealing with insurance, and meeting disclosure rules when selling a property.
Obtaining Permits
Before starting any work to fix subsidence cracks, you need to get the proper permits. Check with your local council about building regulations. They might ask for a structural engineer’s report.
For major repairs, you’ll likely need planning permission. This is true if you’re underpinning the foundation or making big changes to the structure.
The process can take time. Start early to avoid delays. Keep all documents safe. You might need them later for insurance or if you sell your home.
Insurance Claims
Contact your insurer as soon as you spot signs of subsidence. Most home insurance policies cover subsidence damage, but check your policy details.
Your insurer will send a surveyor to assess the damage. They’ll decide if it’s subsidence and what repairs are needed.
Be ready to pay an excess. For subsidence claims, this is often higher than for other types of damage.
Keep records of all cracks and other signs. Take photos and note dates. This helps with your claim.
Disclosure Requirements
When selling a property, you must tell buyers about past subsidence issues. This includes both fixed and ongoing problems.
Fill out the property information form honestly. Mention any subsidence repairs, insurance claims, or current issues.
If you hide subsidence problems, buyers can sue you later. They might claim for the cost of repairs or a drop in property value.
Provide copies of any structural reports or repair documents. This helps buyers understand the situation and can speed up the sale process.
