Difference between cofferdams and caissons
Cofferdams and caissons are both structures that are used when undertaking construction works in areas submerged in under water.
The main difference between the two is that a cofferdam is a temporary structure which is removed after completion of the work, whereas a caisson is built to remain in place as part of the completed structure.
The aim of a cofferdam is to be as watertight as possible to create a dry area in which to carry out the required works, or at least to limit water ingress to a safe level that can be pumped away.
A caisson is typically a box-like structure made of materials such as timber, steel, masonry and reinforced concrete. It may be constructed onshore then floated to the required location, where it is sunk into place, enabling access to the bed to undertake works.
The type of structure being built will determine whether a caisson or a cofferdam is most suitable. The two principal factors influencing the choice are the ground conditions and the depth to which the work is to be taken. In general, cofferdams are suitable for depths of up to 18 m below high water level, while caissons are more suitable for greater depths.
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
PAC report on the Remediation of Dangerous Cladding
Recommendations on workforce, transparency, support, insurance, funding, fraud and mismanagement.
New towns, expanded settlements and housing delivery
Modular inquiry asks if new towns and expanded settlements are an effective means of delivering housing.
Building Engineering Business Survey Q1 2025
Survey shows growth remains flat as skill shortages and volatile pricing persist.
Construction contract awards remain buoyant
Infrastructure up but residential struggles.
Home builders call for suspension of Building Safety Levy
HBF with over 100 home builders write to the Chancellor.
CIOB Apprentice of the Year 2024/2025
CIOB names James Monk a quantity surveyor from Cambridge as the winner.
Warm Homes Plan and existing energy bill support policies
Breaking down what existing policies are and what they do.
Treasury responds to sector submission on Warm Homes
Trade associations call on Government to make good on manifesto pledge for the upgrading of 5 million homes.
A tour through Robotic Installation Systems for Elevators, Innovation Labs, MetaCore and PORT tech.
A dynamic brand built for impact stitched into BSRIA’s building fabric.
BS 9991:2024 and the recently published CLC advisory note
Fire safety in the design, management and use of residential buildings. Code of practice.
NBS launches industry guide for specification writing
Available for free and as immediate download.
Peter Barber’s work revives forgotten building types.
Insights of how to attract more young people to construction
Results from CIOB survey of 16-24 year olds and parents.
Focussing on the practical implementation of electrification.
Preston flood scheme completes primary school SuDS
Three primary schools benefit from SuDS schemes.