Sinking floors can be a worrying sign for homeowners. They often point to a serious issue called subsidence, where the ground beneath a building starts to collapse.
Sinking floors can show that your home’s foundation is moving downwards, which needs quick attention.
You might spot gaps appearing under your skirting boards or notice that your floors are no longer level. These changes can happen slowly or quite suddenly. Either way, they’re a red flag that something’s not right with your property’s foundation.
Sinking floors often mean your home has subsidence issues. Look for uneven floors and gaps under skirting boards.
Quick action can prevent more damage and save money.
Recognising Sinking Floors and Subsidence
Sinking floors and subsidence can cause serious damage to your home. Quick spotting of these issues helps prevent costly repairs down the line.
Warning Signs and Symptoms
Sinking floors often show up as uneven surfaces or gaps near skirting boards. You might notice:
- Sloping or dipping floor areas
- Cracks in floor tiles or wood planks
- Gaps between walls and floors
- Doors dragging on the floor
Look out for wall cracks, especially those wider than 3mm. These often appear near windows or doors. Sticky doors and windows can also point to subsidence.
Outside your home, keep an eye on:
- Leaning walls or chimneys
- Cracks in exterior brickwork
- Sunken paths or driveways
Act fast if you spot these signs. Early action can save you from bigger problems later.
Differentiating Between Settling and Subsidence
Normal settling happens to most buildings over time. It’s usually not a big worry. Subsidence is more serious and needs quick action.
Settling signs:
- Small, hairline cracks
- Cracks that don’t change over time
- Even movement across the building
Subsidence signs:
- Wider cracks (3mm+)
- Cracks that grow over time
- Cracks in a stepped or diagonal pattern
- One part of the building sinking more than others
Time is key here. If cracks grow quickly or you see other fast changes, it’s likely subsidence. Settling happens slowly and evenly.
Professional Diagnosis
If you think you have subsidence, get expert help. A structural engineer or subsidence specialist can check your home properly.
They might:
- Measure and track cracks over time
- Check the building’s structure
- Test the soil under your home
- Use special tools to measure movement
These experts can tell if it’s subsidence or just settling. They’ll also work out what’s causing the problem. This might be:
- Soil shrinkage from dry weather
- Tree roots soaking up water
- Leaky pipes washing away soil
- Old mine workings
Once they know the cause, they can suggest the best fix. This could range from removing trees to underpinning your home’s foundations.
Causes of Sinking Floors and Subsidence
Sinking floors and subsidence can stem from various factors related to the ground beneath a building. These issues often lead to structural problems that require prompt attention.
Soil Properties and Type
The soil under a property plays a big role in subsidence and sinking floors. Clay soils are prone to shrinking when dry and swelling when wet, causing ground movement. This can make buildings shift.
Sandy or gravelly soils are loose and can wash away easily. When water moves through these soils, it can create gaps that cause the ground to sink.
Peat soils shrink a lot when they dry out. This shrinkage can lead to major ground movement and subsidence issues for buildings.
Environmental Factors
Weather has a big impact on subsidence. Long dry spells can make clay soils shrink and crack. This creates gaps under foundations.
Heavy rain after dry periods can cause quick soil swelling. This puts stress on foundations and can lead to cracking and warping.
Trees near buildings can cause problems too. Their roots take water from the soil, making it shrink. Oak, willow, and elm trees are known for causing subsidence issues.
Human Activities
Some human actions can lead to sinking floors and subsidence. Mining work can leave empty spaces underground that later collapse.
Poor drainage around buildings can wash away soil or cause it to soften. This weakens the ground’s ability to support structures.
Leaky pipes under or near a building can erode soil over time. This creates voids that can cause floors to sink or buildings to subside.
Building on filled ground without proper compaction can lead to settling. As the fill material compresses, it can cause floors to sink and walls to crack.
Impact of Sinking Floors and Subsidence
Sinking floors and subsidence can have serious effects on buildings, finances, and safety. These issues often lead to costly repairs and potential dangers for occupants.
Structural Damage to Buildings
Sinking floors can cause major harm to a building’s structure. Cracks might appear in walls, floors, and ceilings. Door frames can become misaligned, making doors hard to open or close. Windows may stick or crack.
In severe cases, walls could start to lean or bow. Pipes might break due to the shifting ground. Foundations can crack, letting water seep in. This can lead to damp and mould problems.
The longer these issues go unfixed, the worse they tend to get. Small cracks can grow into large ones. Slight tilts can become dangerous leans.
Financial Implications
The costs linked to sinking floors and subsidence can be huge. Fixing the problem often requires major work. This might include underpinning the foundation or injecting materials to stabilise the ground.
Insurance may cover subsidence, but this isn’t always the case. You might face high excess charges. Your premiums could go up after making a claim.
The value of your property can drop if it has subsidence issues. This can make it hard to sell. You might need to lower the price to find a buyer.
Safety Concerns
Sinking floors and subsidence pose real risks to people in the building. Uneven floors can cause trips and falls. This is extra risky for older people or those with mobility issues.
Large cracks or leaning walls could collapse without warning. This puts everyone inside in danger.
Broken pipes from ground movement can lead to gas leaks. This creates a fire or explosion risk. Water leaks can cause electrical hazards and further damage to the building.
Investigation and Survey Techniques
Proper investigation and survey techniques are key to diagnosing subsidence issues. These methods help identify the root causes and extent of floor sinking problems.
Site Surveys
Site surveys form the first step in assessing subsidence. A specialist examines the property and surrounding areas for visible signs of problems. They look for cracks in walls or floors, uneven settlements, or foundation displacement.
The surveyor checks:
- Wall cracks (especially diagonal ones)
- Stuck doors and windows
- Sloping floors
- Separation between extensions and main building
They measure crack widths and note their locations. Surveyors also inspect external factors like nearby trees, drainage issues, and soil conditions.
Geotechnical Investigations
Geotechnical investigations dig deeper into ground conditions. These tests help understand soil properties and stability.
Common methods include:
- Trial pits: Excavations to examine soil layers
- Boreholes: Deep drilling to collect soil samples
- Soil testing: Lab analysis of soil strength and composition
These tests reveal information about:
- Soil type and structure
- Moisture content
- Presence of organic material
- Clay shrinkage potential
Results guide engineers in planning appropriate solutions for subsidence problems.
Monitoring Technology
Advanced technology plays a crucial role in tracking subsidence progression. Surveyors use various tools to measure movement over time.
Key monitoring techniques include:
- Laser scanning: Creates 3D models of building structures
- Tilt sensors: Detect changes in wall or floor angles
- Crack monitors: Measure widening of existing cracks
Level surveys help track vertical movement. Surveyors take regular measurements to compare against baseline data.
These tools provide precise data on:
- Rate of subsidence
- Patterns of movement
- Effectiveness of remedial measures
Continuous monitoring helps in making informed decisions about repair strategies.
Addressing the Problem
Fixing sinking floors caused by subsidence requires both quick fixes and long-term solutions. Proper prevention can help avoid future issues.
Short-Term Solutions
When you spot signs of sinking floors, take quick action to prevent further damage.
Place props or acrow jacks under sagging areas to provide temporary support. This stops floors from sinking more while you plan permanent fixes.
Fill any cracks in walls or ceilings with flexible filler. This allows for movement and stops water getting in. Gaps around skirting boards can be filled too.
Keep an eye on the problem areas. Take photos and measure crack widths regularly. This helps track if things are getting worse.
If floors feel unstable, avoid heavy traffic in those rooms. Move large furniture to more solid parts of the house.
Long-Term Remediation
For lasting fixes, you’ll need expert help. A structural engineer can assess the damage and suggest the best solution.
Common methods include:
- Underpinning: This strengthens foundations by extending them deeper or wider.
- Resin injection: A quick, clean way to lift sunken floors and stabilise soil.
- Pile driving: Long supports are driven into stable ground to support the building.
- Beam and base: A concrete raft is built under the house to spread the load.
The right method depends on your soil type, building structure, and how bad the subsidence is. Costs vary, but fixing subsidence is often cheaper than letting it get worse.
Prevention Strategies
Stopping subsidence before it starts saves you time, money, and stress. Here are key steps:
- Maintain gutters and drains to stop water pooling near your house.
- Trim trees near your home regularly. Large trees can dry out soil, causing it to shrink.
- Fix leaky pipes quickly. Water can wash away soil or make it unstable.
- If building an extension, use proper foundations suited to your soil type.
- In dry spells, water the ground around your house to stop soil shrinking.
Check your home often for early signs of subsidence like new cracks or doors sticking. The sooner you spot issues, the easier they are to fix.
Costs and Options for Repair
Fixing sinking floors and subsidence can be costly. The price depends on the repair method and extent of damage.
Estimating Repair Costs
The cost to repair subsidence varies widely. For a typical house, prices range from £5,000 to £50,000 or more. Mass concrete underpinning costs about £400 per square metre. Resin injection is pricier at £550 per square metre.
Smaller jobs like fixing a single wall in a terraced house cost less. Expect to pay:
- £11,000 for resin injection
- £13,000 for mass concrete
- £23,000 for piling
Larger homes need more extensive work. A detached house might cost:
- £16,000 for resin injection
- £21,000 for mass concrete
- £35,500 for piling
Get quotes from several firms to compare prices. Ask about any extra fees for surveys or permissions.
Choosing the Right Approach
The best repair method depends on your home’s specific issues. Common options include:
- Underpinning: Strengthens the foundation by extending it deeper or wider.
- Resin injection: Fills voids and lifts sunken areas.
- Piling: Drives supports deep into stable ground.
- Tree removal: Stops moisture loss if trees are the cause.
Underpinning suits severe cases but is costly and disruptive. Resin injection works well for minor issues and is less invasive. Piling helps with very unstable ground.
A structural engineer can advise on the best method. They’ll assess the damage and soil conditions. Their input ensures you choose an effective, long-lasting solution.
Contractor Selection
Picking the right contractor is crucial for a successful repair. Look for firms with:
- Proven experience in subsidence repairs
- Proper insurance and guarantees
- Membership in trade bodies
- Positive customer reviews
Ask for detailed quotes and timelines. Compare at least three different companies.
Check if they offer warranties on their work.
Be wary of very low quotes. They might cut corners or use poor materials. Ask about the qualifications of the workers who’ll do the job.
Consider getting a free quote from a specialist. They can give you a clear idea of costs and options for your specific case.
