Subsidence
INTRODUCTION
Subsidence of properties occurs when the formation below the foundations is disturbed, and the foundations move.
CAUSE OF SUBSIDENCE
The main causes of subsidence are:
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Broken Drains
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Effect of Tree Roots
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Mine Workings
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Underground Springs
SOIL TYPES
These can be either granular or cohesive. Granular soils are generally sand and cohesive soils are clay.Highly shrinkable clays are located in the South of England. The Midlands and the North of England have medium shrinkable clays with areas of low shrinkability.
SITE INVESTIGATIONS
The condition of a building's foundations and the cause of subsidence can be assessed by the following methods:
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Camera Survey and test all drains and Water Service Pipes
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The excavation of Trial Pits
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Bore Holes
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Geotechnical Analysis of the formation
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Tree Root analysis
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Inspect Archive drawings of the building / structure affected
REPAIR
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Underpin using either mass concrete, mini piles, or piles
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Reinforced Concrete Raft; the structure is propped and has a reinforced concrete raft built below it
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Hoopsafe System; in-situ reinforced concrete beams are built around and through the property and then prestressed to form a raft
INSURANCE CLAIMS
Most subsidence damage to properties in the domestic sector, but not all cases in the commercial area, are subject to insurance claims.
HOW WE WORK
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The site is visited, a visual inspection is made and a Structural Engineers report is prepared
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If required further investigations such as drain tests, camera surveys of drains and trial pits are carried out
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In cases of nominal damage, the property is monitored for a year or more to check if the movement is progressive
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A Schedule of Works detailing the repairs to be carried out, is prepared for the repair of the property, and tenders are sent out
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A contractor is appointed, we inspect and certify the work on site
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