Strengthening House Structures to Protect Against Shift From Flood or Wind Forces

Floods November 03, 2015 Print Friendly and PDF

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This publication is intended to give quick, brief answers to the many issues that arise..

A structural building engineer or architectural engineer can help you decide the type of reinforcement your house structure may need to strengthen it against heavy winds, storm surges, rapidly moving water, and flooding. However, no one can say for sure what will happen because the length and intensity of the storm cannot be accurately predicted. Most existing structures can be reinforced to protect against structure shift. However, some reinforcement methods are easier to implement when you are building or remodeling a house. Before reinforcing a house structure, contact your local building inspectors and code officials. Your community may have special regulations in place.

Consider These Ideas for Strengthening Your Structure

Protect exterior foundations and basement walls with water resistant sealant and drain tile. Source: North Dakota State University, Ken Hellevang.
  • Attach exterior walls to the foundation. Use corrosion resistant metal connectors to secure wall studs to the sill plate. Drill holes through the sill plate into the foundation and install anchor bolts. The Institute of Building and Home Safety suggests 5/8-inch diameter anchor bolts no more than 6 feet apart to add resistance to shifting. The Federal Emergency Management Agency (FEMA) recommends that anchor bolts in block foundations should be at least 15 inches long and set into concrete.
  • Wall and foundation connections include stud-to-top plate, stud-to-stud, header, joint-to-beam, wall-to-foundation, continuous rod, and pile connectors.
  • Make sure all supports are very secure and the underneath portions of the home are free from debris and storage items if the foundation is intended to allow water to flow through it.
  • Protect basement or slab on grade foundations with an exterior water resistant covering. Install adequate drain tile around the below-grade foundation footing perimeter.

 

  • Caulk and seal seams and connections.
  • The ground or lot should drain away from the house. Soil should slope away from the foundation at a 5 to 10 percent slope for at least 10 feet and then continue sloping away.
  • For new homes and remodeling, consider cast-in-place concrete wall systems with an interior metal reinforcement structure rather than concrete masonry block construction.
  • Reinforce attached garages. Garage doors are a weak point. The whole house is exposed to potential damage if an attached garage door is damaged or forced in or off. Strengthen the end and center supports. Consult with the door manufacturer, a professional garage door business, or installer about methods to reinforce the doors. You can replace an existing double garage door with a garage door style tested for hurricane wind loads.

 

Secure roof to walls, walls to sill plate and to foundation. Source: University of Nebraska-Lincoln Extension, Shirley Niemeyer

There are many other ways of strengthening and reducing the risk to a structure of shifting on its foundation. These methods reduce the risk but may not prevent damage when fast moving water, wave action, debris, and winds create pressures on the structure. Obtain additional information from FEMA, American Red Cross, and the Institute of Business and Home Safety, and from engineers who specialize in building structures.


NOTE: If your home is located in a flood velocity or V zone, the threat to the home is high velocity water and wave action that can cause structural damage. For V zones, home relocation is suggested. If relocation is not possible, elevation is recommended. To find out more about moving or elevating your home, refer to Relocating Your Home or Elevating Your Home. You may also wish to read Above the Flood: Elevating Your Floodprone House, FEMA publication 347, May 2000.

Slope soil away from the foundation. Source: University of Nebraska-Lincoln, Communication and Information Technology.

To find out your flood risk and zones, go to FloodSmart.gov and click on What's Your Flood Risk?. For more information on recommendations for your zip code area, visit the Fortified for Safer Living resource at the Institute of Business and Home Safety.


Additional information on how to protect your house from flood, wave, and wind forces.

Resources

Federal Emergency Management Agency. Home Builder's Guide to Coastal Construction. Asphalt Shingle Roofing for High-Wind Regions. Technical Fact Sheet #20, Aug. 2005.

Federal Emergency Management Agency. Home Builder's Guide to Coastal Construction.Storm-Resistant Roofing.

Reinforce garage doors. Illustrations courtesy of Purdue University, Kimberly Batta.

Federal Emergency Management Agency. Home Builder’s Guide to Coastal Construction. Use of Connectors and Brackets. Technical Fact Sheet #17.

Federal Emergency Management Agency. Home Builder’s Guide to Coastal Construction. Roof Sheathing Installation. Technical Fact Sheet #18.

Federal Emergency Management Agency. Home Builder's Guide to Coastal Construction. Roof Underlayment for Asphalt Shingle Roofs. Technical Fact Sheet #19.

Federal Emergency Management Agency. Homeowner's Guide to Retrofitting: Six Ways to Protect Your House from Flooding chapters 3 and 7.

Parker, D. (2006). Post-Hurricane Opportunities. Hurricane Season. Home Energy, pp. 38-40.

U.S. Department of Housing and Urban Development. Durability by Design: A Guide for Residential Builders and Designers.

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