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Subsidence
Subsidence is one of the most serious and distressing problems a property owner or manager can face.
Catalyst is a market leader in delivering subsidence investigation services. From targeted investigations to identifying and repairing causation, whether your property is at risk from subsidence, has been seriously damaged, or has suffered collapse, Catalyst is here to help.
With the UK experiencing more volatile weather, caused by climate change, resulting in frequent periods of heavy rain fall interspersed with longer periods of dry weather, Subsidence risk is a growing concern for many property owners across the UK.
Risks to property are significant. They include additional maintenance and repair costs, reduced property values, and loss of the property altogether, through serious damage or collapse.
What is subsidence?
Subsidence is the vertical downward movement of a building foundation caused by loss of support of the site beneath the foundations. It can occur suddenly or gradually.
Subsidence – our expertise
Catalyst will investigate subsidence problems and support contractors to put in place robust and practical solutions. Our aim is to tackle subsidence threats as early and quickly as possible, giving property owners and managers peace of mind and supporting property value.
Our subsidence service is led by Paul Duddle, Catalyst’s Senior Technical and Networks Manager. He has more than 25 years of technical experience carrying out subsidence investigations and remedial work and training other professionals.
He is also an executive member of the Subsidence Forum, a national body of experts drawn from civil engineering, building surveying and insurance professions, who work together to advance standards and practice in the solution of subsidence issues.
Subsidence services – who we work for
Catalyst provides subsidence investigation services for a wide range of customers. They include insurance providers, loss adjusters, building surveyors, building maintenance companies, building contractors, housing landlords, both private and social, and private homeowners.
Insurance Companies
Loss Adjusters
Commercial
Property Landlords
Public Organisations
Home Owners
Our subsidence services
Catalyst can deploy a comprehensive range of investigative and analytical services to tackle subsidence. Our aim is to fully understand the subsidence issues affecting a particular site, so we can support the implementation of the best and most cost-effective long-term solutions.
Site investigations
We carry out thorough site investigations to establish the precise factors determining subsidence and its impact on specific buildings. These site investigations can take many forms and will be determined by the unique circumstances of each site.
Drainage investigation and repair
Catalyst can carry out a full range of drain surveying, including carrying out CCTV surveys using robotic cameras or laser and 3D camera profiling of pipes and chambers.
Based on findings, we can also carry out drain unblocking, drain repairs and rehabilitation, including pipe lining, and drain excavation and replacement, or drain diversion.
Trial hole and borehole investigations
We carry out trial hole (also known as trial pit) investigations to see the condition and material types in structure foundations. We measure the depth from the surface to the top, spread, and underside of the foundation. This is called a foundation drawing or log.
A borehole can then be drilled at the bottom of the trial hole to assess the ground conditions under the foundation. We can also take samples from under the foundation that can be sent for laboratory testing.
A remote borehole investigation is sometimes carried out away from the area of concern so ground conditions at the two locations can be compared.
Shear vane and Mackintosh probe in-situ testing
Catalyst can carry out shear vane tests to measuring the undrained shear strength of cohesive soil. This helps assess the likelihood of a soil breaking down, resulting in increased subsidence risks.
Mackintosh probe in-situ testing helps identify the variability of soil structures at different depths. This provides valuable information about soil conditions that can cause subsidence or increase the risk of it occurring.
Laboratory soil testing
Where necessary, Catalyst will arrange for laboratory tests of soil and other material samples to identify physical and chemical properties that influence subsidence risks. Full reports of all laboratory tests will be provided.
Laboratory root testing
We can also arrange for the laboratory testing of tree and plant roots to assess if they are increasing subsidence risks or are associated with structural damage.
Crack and level monitoring
Catalyst puts in place monitoring systems to assess crack development and level movement across your premises. This can range from regular visual checks to the installation of sophisticated remote monitoring and alarm systems to continuously assess your property and allow rapid intervention if it is needed.
Arboriculturalist reports
We can prepare arboriculturalist reports on the way trees near properties are increasing subsidence risks or causing real damage. This service includes comprehensive analysis of potential subsidence risks associated with proposed tree planting and landscaping schemes.
Subsidence – what to look out for
- Vertical and diagonal cracking in specific areas and tapering in width between the top and bottom of the property
- Cracks through the damp proof course down into the foundations
- Cracking both internal and external in the same area of wall
- Rucking of wallpaper at corners between walls and ceilings
- Re-pointing of mortar joints diagonally or vertically up walls indicating past problems or possible subsidence
- Distortion of openings causing doors and windows to stick
- Cracks in structures appearing after a prolonged period of dry weather
- Seasonal opening and closing of cracks
Common causes of subsidence
Trees
Trees and vegetation extract moisture for the ground. In clay soils this can result in the ground becoming desiccated and causing the clay to shrink. This shrinkage can result in the foundation losing support settling and cracking.
Drains
Drains and sewers can leak causing the softening of supporting soils or washing away fine materials such as sandy soil resulting in loss of support to the house foundation
Culverts and natural springs
These can wash out or soften the ground, increasing the risk of subsidence
Water supply pipes
Water supply pipes can leak causing the softening of supporting soils or washing away fine materials such as sandy soil, resulting in loss of support to the house foundation
Mining
Voids from old mines. Some of the oldest mine workings have not been officially recorded or fully surveyed so can cause sudden subsidence problems.
Poor construction
Inadequate foundations for structure and ground type can result in structures subsiding.
Road traffic
Continuous vibrations from heavy nearby traffic can, over time, cause changes in soil structure, leading to subsidence
