wall section of breakaway walls and piers

Understanding Breakaway Walls and Piers in Flood-Prone Areas

When building a house in a flood-prone area, it's crucial to consider the risks of water damage and structural failure. One effective way to mitigate these risks is by installing breakaway walls and piers. In this article, we'll explore what these components are, how they work, and why they're essential in flood zones.

Retaining Grades and Facilitating Slab Installation

Breakaway walls and piers allow the abutting grades to be retained, which enables seamless slab installation. This design approach also promotes a natural use of the surrounding area while maximizing freeboard height. By maintaining additional freeboard, we can adhere to CRMC SDE 3' maps where feasible, subject to site requirements, local hydrology, or other factors within sound professional judgment.

Flood Zone Considerations

If you're building in a flood zone, it's essential to have a garage or storage area set below the house. Geotechnical borings are typically required prior to design, as they help us identify potential issues and plan accordingly. Some contractors may overlook these small details, leading to costly foundation repairs down the line.

Helical Piles and Pier Foundations

In flood-prone areas, we often use helical piles (helical screws) to anchor the house and account for wave action and scour. Piers are typically placed on a 10' to 14' grid, with a 16'x16' concrete pier serving as the foundation. This design includes a Replaceable Bonnet Gate Valve or stainless steel valves, along with steel rebar reinforcement connected to a 2'x3' grade beam on a grid or waffle pattern.

V-Zone and Coastal 'A'-Zone Requirements

If your site is within a V zone or Coastal 'A' zone, a pier foundation with breakaway walls is required. This design ensures that hydrostatic pressures can be equalized (inside and outside the structure), preventing buckling or collapse.

Flood Vent Installations

In flood zones A or AE, a traditional foundation can be used, such as a 12'x24' footing with a 12' foundation wall. However, flood vents (typically smart vents) must be installed in the direction of flow at no higher than 1' above the grade or slab.

X-Zone Exemptions

If your site is within an 'X' zone (formerly zone 'C') and well above any adjacent flood elevations, then no special flood considerations are required. This exemption applies when the structure is not at risk of flooding.

Designing a Suitable Foundation

Our team uses soils, geotechnical data, and site information to design an appropriate foundation for any home or structure. By considering factors like site data, flood zone, grades, architectural design, and more, we can create a safe and reliable foundation that meets local building codes and regulations.

In conclusion, breakaway walls and piers are crucial components in flood-prone areas, allowing us to retain grades, facilitate slab installation, and ensure the structural integrity of our structures. By understanding these components and how they work, homeowners and builders can make informed decisions when designing and building their properties in high-risk flood zones.

Wall section of breakaway walls and piers