Components of a Seawall

Seawalls are complex structures made up of many different components working together to provide protection and support. An understanding of seawall components informs decisions about repair and maintenance. Let’s examine the various components of a seawall and see how they work together to provide protection and support for waterfront property.

Seawall Components

There are several key components that are common to most seawalls. These include:

Foundation

The foundation of a seawall is the base upon which the rest of the seawall is built. It is important that the foundation is strong and stable to support the weight of the seawall and withstand the forces of the water.

Backfill Material

Backfill material is used to fill in the area behind the seawall and provide additional support. This can be any type of material, such as sand, gravel, or soil, depending on the specific needs of the project.

Filter Fabric

Filter fabric is a generic term used to describe geotextiles whose primary function is allowing water to pass through the vertical seams (panel joints) and weep holes of the seawall panels while reducing soil migration into the waterway from behind and under the seawall.  Filter fabric is installed at the time of panel installation and is secured in place with furring strips behind the seawall.  Filter fabric is most commonly installed behind concrete panel seawalls.  Many vinyl and sheet pile seawall structures do not include filter fabric due to the wrap-around tongue-and-groove seems. Many types of filter fabrics are being installed with new seawall construction.  As is the case with much of modern construction, the quality of today’s material is inferior to older versions.

Seawall Cap

A seawall cap is a horizontal structure that is installed at the top of a seawall. It serves several important functions, including:

Protecting the Top of the Seawall

The seawall cap helps to protect the top of the seawall from damage caused by weather, waves, and other external forces. It can also help to prevent debris and sediment from accumulating on the seawall, which could otherwise cause erosion and damage to the structure.

Providing a Walking Surface

The seawall cap can provide a flat, stable surface for people to walk on, which is useful if the seawall is located in a public area or is used as a recreational space.

Improving the Appearance of the Seawall

A seawall cap can add a finishing touch to the seawall, improving its overall appearance and making it more aesthetically pleasing.

Enhancing the Functionality of the Seawall

Depending on the design of the seawall cap, it may also be used to support additional structures, such as handrails, lighting, or seating.

Seawall caps are typically made of concrete, but can also be made of other materials, such as wood or stone. They are an important component and play a critical role in protecting the structure and enhancing its functionality.

Drainage System

A seawall should have a drainage system to allow water to flow through or around the seawall, rather than accumulating behind it. A drainage system prevents damage due to hydrostatic pressure buildup and ensures that it remains stable.

Deadman Anchor System

The deadman anchor system consists of a series of anchors that are installed behind the seawall and are connected to the structure by cables or rods. These anchors are typically made of concrete, steel, or other durable materials and are designed to resist the forces of the water and the weight of the seawall. This system is used to provide additional support and stability to the structure. It is particularly useful in areas with strong wave action or high hydrostatic pressure, where the seawall may be subjected to significant forces. The function of the system is to distribute the load of the seawall across a larger area, reducing the stress on any one point and helping to prevent failure. By providing additional support and stability, the system can extend the life of the seawall and ensure that it continues to provide effective protection.

Protective Coating

Many seawalls have a protective coating on the surface to help protect against the elements and extend the life of the seawall. The coating can be a sealant, paint, or another type of material, depending on the needs of the project.

Four Types of Seawalls

Seawalls are constructed with a variety of materials, each featuring unique characteristics and benefits. Some of the most common types of seawalls include:

Concrete Seawalls

These seawalls are made of poured concrete and are a popular choice due to their durability and strength. Concrete seawalls are often used in areas with strong wave action or heavy boat traffic.

Sheet Pile Seawalls

These seawalls are made of interlocking sheets of metal, vinyl, or composite that are driven into the ground. Sheet pile seawalls are typically used in areas with softer soil or where the water level is expected to fluctuate.

Rock Seawalls

Rock seawalls (a.k.a. Rip Rap) are made of large, heavy stones that are placed along the shoreline to create a barrier. Rock seawalls are often used in areas with strong wave action or to provide a natural-looking barrier.

Wooden Seawalls

Wooden seawalls are typically the least expensive to construct. They are most often used in residential applications. Wooden seawalls tend to have the shortest lifespan of all the seawall types profiled in this article.

In conclusion, seawalls are critical structures that serve a variety of practical functions for waterfront property owners and other stakeholders. There are several types of seawalls to choose from. Once installed, is important to work with a skilled and experienced contractor to ensure proper maintenance and repair.