Updated at: 25-09-2021 - By: Lucas

A cofferdam is a device that is used to prevent the sea from coming inside a boat when it is docked. The cofferdam keeps the water outside and thus out of the boat.

Cofferdams are made of wood and sometimes they are made of metal. These days, you will see that there are many different kinds of cofferdams. Each of them has its own special purpose. There are many things you should know about cofferdams. You should know how to make one, how to repair one, where you can buy them and so on.

You can learn all this in this article.

Cantilever Sheet Piles

Cantilever Sheet Piles

Cantilever sheet piles are long, slender, cylindrical steel or concrete structures with a triangular cross section. These are driven into the riverbed and then covered with soil or gravel. Once in place, the pile extends above the surrounding ground level and forms a platform or “cantilever” that supports the structure above it.

A cantilever sheet pile cofferdam is a temporary structure that is built around a foundation to keep the surrounding area dry while a permanent structure is being built on that foundation. Cantilever sheet piles are long, narrow timbers that are driven into the ground and then “piled” one on top of another like giant wooden toothpicks. These long, slender piles are driven deep into the ground and are connected together with metal ties. The entire structure is then covered with a waterproof membrane.

Once the permanent structure is completed, the cantilever sheet pile cofferdam is removed by pulling it up and out of the ground. This leaves an empty hole that can be filled with dirt or some other type of material.

Sheet piles are used for a variety of purposes including flood control, river stabilization, and shoreline protection. Their primary use, however, is for cofferdams. Cofferdams are large, circular, vertical barriers that are placed around a construction site to prevent the escape of any water that might seep into the area. 

These cofferdams are usually constructed of reinforced concrete and have a diameter of about 16 to 24 feet. They are designed to withstand very high pressures and are capable of holding back very large volumes of water.

Cellular Cofferdams

A cellular cofferdam is a form of temporary flood control barrier used during the construction of a new or retrofitted channel or river diversion structure. It is usually constructed of either earth or concrete and is designed to be removed once the diversion structure has been completed.

Cellular cofferdams are usually constructed in a square or rectangular shape and are made up of a series of individual cells or compartments that are held in position by a framework of steel or other structural members. 

Each compartment is filled with earth or concrete and the entire cofferdam is anchored to the river bed or channel. The top of the cofferdam is then covered with a waterproof membrane and secured in place. This forms a waterproof seal between the top of the cofferdam and the river bed or channel.

Cofferdams are used in conjunction with concrete forms to create a mold for the concrete to fill. A cellular cofferdam is constructed of interlocking steel plates that are bolted together. It is designed to allow the concrete to flow over it and create a smooth, flat surface. Cellular cofferdams are often used when a concrete slab needs to be poured over a preexisting surface. This is because the concrete will flow over the cellular dam and create a smooth, level surface.

A cellular cofferdam is also a very economical way to pour concrete. It is designed to be disassembled after the concrete has cured. It can then be stored until needed again. This makes it an ideal choice for construction sites that need to pour a lot of concrete. When the concrete slab is poured, the cellular dam is assembled and the concrete is allowed to flow over it. This allows the concrete to cure and creates a level, flat surface.

Braced Cofferdams

Braced Cofferdams

A braced cofferdam is a temporary structure that is used to build a foundation for something permanent. This type of cofferdam is typically made out of wood and is braced with wooden timbers. It is designed to be removed after the construction project is completed.

In the case of a magazine rack, this type of cofferdam would be used as a temporary structure until the permanent magazine rack could be built. After the magazine rack was constructed, the braced cofferdam would be removed and the magazine rack would be left permanently in place.

Aqua-Barrier Water-Inflated Dams

An aqua-barrier water-inflated dam is a water-filled, inflatable tube that is designed to be used as a barrier to prevent the passage of fish. The water-filled dam is made of thin, flexible material and has an opening at one end that allows water to flow through it. This creates a hydraulic head that pushes water back into the reservoir.

The water-filled dam is connected to a length of tubing that extends from the top of the dam to the bottom. The open end of the tubing is then secured to a weighted anchor line. When a fish tries to pass through the dam, the weight of the fish will cause the tubing to be pulled taut. This creates a pressure head that prevents the passage of the fish.

Aquabarrier dams are used in many different ways. One common use is as a retaining wall. Another is for erosion control. Yet another is as a pond dam to create a small lake. You can also use them as playground structures and as decorative fountains. They are ideal for these applications because they are extremely strong and can be made in an almost unlimited number of shapes and sizes.

Earthen Cofferdam

Earthen Cofferdam

An earthen cofferdam is a temporary structure that is used to keep water out of a trench being excavated for a foundation or similar construction project. Earthen dams are constructed of earth and timber and are designed to be removed after the work is completed. The top of the dam is usually open so that any water that does get through will drain away.

The earthen dam is one of the cheapest ways to prevent water from interfering with your construction project. It is also very easy to construct. Basically, what you need to do is dig a trench long enough to accommodate the length of the foundation you wish to lay. 

Then, you build an earthen dam across the trench and backfill the sides of the trench with dirt and/or gravel. This forms a temporary enclosure around the foundation area. After the construction project is finished, all you have to do is remove the dam and your foundation will be ready for final construction.

An earthen cofferdam is a waterproof structure built over a prepared foundation. Cofferdams are used to create a temporary watertight compartment or “sack” in which other construction can occur. The top of the sack is made of earthen fill and is packed tightly around the outside of the structure to prevent water from seeping in.

A typical earthen cofferdam has a diameter of 4 to 6 feet and a height of 2 to 3 feet. The top of the dam is sloped at an angle of about 1/4 inch for every foot of height. This allows water to flow off the top of the dam easily.

Rockfill Cofferdam

A rockfill cofferdam is a temporary structure that is used to keep the earth from moving or drying out while you build something. It consists of a wooden frame with an inflatable rubber membrane stretched across it. The frame is built around a number of steel pipes called “rockpiles”. 

These rockpiles are driven deep into the ground and connected together with metal connectors. The membrane is attached to the frame with metal straps. This allows the membrane to expand and contract with changes in the water level.

When the area needs more room, the rockpiles can be removed from the bottom of the structure and the straps are cut. This allows the membrane to deflate and the frame to collapse. After this, the rockpiles can be reattached to the bottom of the structure and the process is repeated until the cofferdam is no longer needed.

Rockfill dams are typically used when a large excavation is needed. These dams are also used when a large excavation needs to be filled with concrete. The rock fill prevents the concrete from washing away and ensures that the excavated area will be level and ready for construction.

Single-Walled Cofferdam

A single-walled cofferdam is a large metal box with wooden sides that is used to build a foundation under a structure such as a building or a dam. A two-sided cofferdam has side walls on both sides of the base. A three-sided cofferdam has side walls on all four sides of the base. A cofferdam with no side walls whatsoever is called a “false” or “dry” cofferdam.

A false or dry cofferdam is usually used when there is no other choice because the sides of the base will have to be left exposed to make room for the construction equipment to get in place. The sides of a dry cofferdam are usually notched out so they can be easily removed after the concrete has cured. Dry cofferdam are not as strong as a full-sized one and are not usually used unless the job requires them.

A single-walled cofferdam is a temporary structure that is used to hold back the earth while the construction of an underground or underwater cavity goes forward. The single-walled cofferdam is constructed of a flexible material such as rubberized fabric that is secured to a framework of wood or metal.

Once the cavity is complete, the flexible walls are removed and the resulting void is backfilled with dirt or concrete. This process is repeated until the desired depth of the foundation has been achieved. Single-walled cofferdams are typically used when the ground is unstable or likely to move. They can also be used when there isn’t enough room for conventional forms of construction.

Double-Walled Cofferdam

Double-Walled Cofferdam

A double-walled cofferdam is a temporary structure that’s used to keep the surrounding area dry while you pour the concrete into the forms. A double-walled cofferdam is usually made of plywood or OSB. It’s constructed with two layers of material that are held together by metal or wooden screws. The screws are spaced so that there are no gaps or holes in the perimeter of the structure. This keeps water out.

The top layer of the double-walled cofferdam is perforated with small holes. These holes let the water vapor escape, but they don’t let any water get through to the interior.

It consists of two layers of rubberized fabric, each with a vinyl backing. The outer layer is a weatherproof barrier that prevents water from getting to the material inside. The inner layer is an adhesive-backed polyethylene film that holds the two layers of fabric together. This prevents the two layers of fabric from coming apart when the pressure is released.

The two layers of fabric are attached to a frame and held in place by adjustable wooden pegs. The frame is made out of either 2×4s or 2×6s. The pegs are adjusted until the entire structure is taut and water cannot get between the two layers of fabric.

Circular Type Cellular Cofferdam

A cellular cofferdam is a circular type of dam that is constructed from a latticework of steel pipes. This type of dam is often used when you are building a foundation that has a large area or when you need to create a very stable and strong base for your structure. A cellular cofferdam is constructed with a series of concentric rings of pipes that are held together with horizontal members. The horizontal members are connected to vertical members that pass through the center of each ring of pipes.

This particular type of cofferdam is usually made from mild steel and it is designed so you can dismantle it for transport and storage. A cellular cofferdam is perfect for creating a very solid and stable base for any structure. It is especially useful when you are constructing a basement or a large foundation. 

You should know though, that this type of dam is not always circular. Sometimes it is square, rectangular, or even an octagon. However, the most common shape for a cellular dam is circular.

This type of cofferdam is often used in situations where there is a lot of earth movement or the ground is unstable. The polyethylene film prevents the steel rings from welding together and allows the excavation to be dug out without the risk of a cave-in.

Diaphragm Type Cellular Cofferdam

Diaphragm Type Cellular

A diaphragm cell is the most common form of construction for a water tank. A diaphragm cell has a flexible rubber membrane which is clamped between the top and bottom plates of the tank. This membrane divides the tank into two sections; one above the membrane and one below. 

The upper section is where the water is, the lower section is empty space. When the water reaches the top of the tank, it pushes on the membrane, causing it to bulge outwards. This forces the top plate upwards, creating a vacuum which sucks water back down into the tank.

This process continues until the water level is even with or slightly below the membrane. At this point, there is no more force pushing the membrane up, so the top plate will remain in place and the water will stop draining out.


Where is used a cofferdam?

Generally, cofferdams are used in construction sites for different kinds of construction works like: A cofferdam can be used for any kind of construction work.

For example, a contractor may use it to create a pool for the foundation of his building or a city may use it to build a new bridge over a river.

What is the purpose of a cofferdam?

A cofferdam is a temporary structure used to isolate a certain area from the rest of a body of water. This area can be used for a variety of construction projects, including bridge and dock building.

In simple terms, a cofferdam is a big, semi-circular piece of wood or metal that sits under the water and prevents it from seeping (or “leaking”) into whatever is being constructed above the water.

What is the best cofferdam?

The best cofferdam depends on the conditions of your job site. If you are going to be working in a dry, dusty environment with lots of heat and little ventilation, then you should use a rubberized asphalt-coated polyethylene plastic dam. This type of cofferdam is lightweight, extremely strong, has a non-skid bottom, and will not buckle or warp under pressure.


A cofferdam is a large structure built around a ship’s hull during the construction process. It is used to keep the ship above water while the construction workers work underneath the hull. Cofferdams are usually made out of reinforced concrete and are very heavy. They can weigh hundreds of tons.

Cofferdams are often needed when building a new ship because they prevent the ship from sinking to the bottom of the ocean while the workers are constructing it. Once the workers are finished, the cofferdam is taken off the ship and the ship is floated up onto the dry land. This allows the workers to quickly finish the construction of the ship.