Anchor building to its foundation

Overview

Anchoring a building to its foundation is the process of securing a building’s walls to its foundation using large bolts. Anchoring is an important, and typically a regulated, requirement for new construction and all structures requiring substantial improvements within the special flood hazard area (SFHA). If not properly anchored, the force of floodwater onto the side of a building can easily move the building off of its foundation. While flooding alone can cause extensive damage to a building, flooding combined with the movement of a building off of its foundation can be catastrophic.

Anchoring a building to its foundation can prevent structural damage during a flood since anchoring systems are designed to prevent the flotation, collapse, or lateral movement of a building. While anchoring can help prevent significant structural damage to a building by keeping it in place, flood damage may still occur due to floodwater entering the building or hydrodynamic and hydrostatic forces exerting extreme pressure on the exterior of the building. Depending upon a building’s foundation type (e.g., basement, crawlspace, slab-on-grade, pilings, posts, or columns), its anchoring system may be used alongside building elevation and wet or dry floodproofing techniques for more comprehensive flood risk reduction.

In addition to anchoring the principal building, anchoring systems should also be used to secure accessory buildings, such as detached garages, storage sheds, and aboveground fuel storage containers.

Next Steps

1. Contact your local government to learn more about your property’s flood history and Base Flood Elevation, and to determine what federal, state and local permitting, code or ordinance requirements you will need to follow, before any work starts. If you are not sure who to talk to, check out our “who to contact” page.
2. Designing and installing the proper anchor system can be complex, so it is recommended that you hire a registered design professional to provide services. Your local floodplain administrator may be able provide guidance.
3. Check out the financial assistance page to see what funding or financing opportunities might be available to you.

Special Considerations

• If your structure is in less than fair condition, this mitigation option type is not recommended. The only mitigation option types recommended for structures in fair to poor condition are acquisition, demolition, and the purchase of flood insurance or business interruption insurance.
• There are specific anchoring requirements for manufactured homes and all buildings located in a FEMA V Zone (coastal area), where flood velocities or wave action can be significantly stronger than in other areas of the SFHA. In hurricane-prone areas, a building may also need its roof anchored to the building using hurricane straps. Contact your local floodplain manager to learn if these additional requirements pertain to you.
• Ensure compliance with all applicable National Flood Insurance Program (NFIP) requirements and local building codes. The NFIP sets minimum standards and allows individual communities to adopt their own additional or more stringent requirements via local floodplain management ordinances, regulations, and laws. Consult your local officials to learn about your community’s NFIP compliance requirements, including its substantial improvement threshold.
• If your building sustained substantial damage during a recent flood event, you may be required to bring it into compliance with NFIP and local floodplain management regulations. Your local floodplain manager can give more information about this.
• Be careful not to redirect water flow from your property onto another property. No adverse impact (NAI) floodplain management is an approach that ensures the action of any property owner, public or private, does not adversely impact the property and rights of others. NAI calls for any adverse impact caused by a project to be mitigated as part of the project. By following NAI principles, you can: prevent flooding from increasing or damaging others; see a reduction in flood losses over time; and avoid challenges and lawsuits over causing or aggravating a flood problem.
• Create a disaster plan. Be aware of all actions you will need to take once you receive warning of an oncoming flood event — and how much time each action will take to complete. Actions could include ensuring flood vents are clear, installing flood shields, or closing barrier gates. Annually, inspect all removable pieces to make sure they are in good condition — and you have all necessary parts. Make sure whoever is identified to complete each action in your disaster plan knows how to perform the action, is physically able, and will be onsite. Once everything is in place to protect your home, you should evacuate to higher ground.
• Contact a local flood insurance representative to learn more and get a quote, if you do not already have flood insurance. While flood insurance will not prevent flood damage, it will help offset the cost of flood damage to the homeowner or business owner. (Most homeowner’s insurance policies do not cover flood damage.)
• Renters and those who own specific types of property may be limited in which mitigation options they can undertake or have different requirements to which they must adhere. If you are a renter or own any of the following listed property types, click through to learn more: Renter; Unit in a multifamily residence; Manufactured home; Farm/ranch; Historic property; New construction.