U.S. flag
        An official website of the United States government
          Here’s how you know
        Here’s how you know**Official websites use .gov**
              
              A **.gov** website belongs to an official government organization in the United States.
        **Secure .gov websites use HTTPS**
              
              A **lock** (  A locked padlock
) or **https://** means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites. https://www.nist.gov/el/fire-research-division-73300/wildland-urban-interface-fire-73305/hazard-mitigation-methodology-21
  Search NIST
    Search
              Menu

      


Close
    Topics
        All Topics
                                                        Advanced communications
                                                        Artificial intelligence
                                                        Bioscience
                                                        Buildings and construction
                                                        Chemistry
                                                        Climate
                                                        Cybersecurity
                                                        Electronics
                                                        EnergyEnvironment
                                                        Fire
                                                        Forensic science
                                                        Health
                                                        Information technology
                                                        Infrastructure
                                                        Manufacturing
                                                        Materials
                                                        Mathematics and statisticsMetrology
                                                        Nanotechnology
                                                        Neutron research
                                                        Performance excellence
                                                        Physics
                                                        Public safety
                                                        Resilience
                                                        Standards
                                                        Transportation
            Publications
            Labs & Major Programs
        Laboratories
                                Communications Technology Laboratory
                                  Engineering Laboratory
                                  Information Technology Laboratory
                                  Material Measurement Laboratory
                                  Physical Measurement LaboratoryUser Facilities
                                NIST Center for Neutron Research
                                  CNST NanoFab
                                                        Research Test Beds
                                                        Research Projects
                                                        Tools & InstrumentsMajor Programs
                                Baldrige Performance Excellence Program
                                  CHIPS for America Initiative
                                  Manufacturing Extension Partnership (MEP)
                                  Office of Advanced Manufacturing
                                  Special Programs Office
                                  Technology Partnerships Office
            Services & Resources
        Standards and Measurements
                                Calibration Services
                                  Laboratory Accreditation (NVLAP)
                                  Quality System
                                  Standard Reference Materials (SRMs)
                                  Standards.gov
                                  Time Services
                                  Office of Weights and MeasuresSoftware
                                                        Data
                                Chemistry WebBook
                                  National Vulnerability Database
                                  Physical Reference Data
                                  Standard Reference Data (SRD)
                                                        Storefront
                                                        License & PatentsComputer Security Resource Center (CSRC)
                                                        NIST Research Library
            News & Events
        News
                                                        Events
                                                        Blogs
                                                        Feature Stories
                                                        AwardsVideo Gallery
                                                        Image Gallery
                                                        Media Contacts
            About NIST
        About Us
                                Leadership
                                  Organization Structure
                                  Budget & Planning
                                                        Contact Us
                                                        Visit
                                                        Careers
                                Student programsWork with NIST
                                                        History
                                NIST Digital Archives
                                  NIST Museum
                                  NIST and the Nobel
                                                        Educational Resources
 
 Engineering Laboratory /                  Fire Research Division
      Wildland-Urban Interface Fire Group
    
      
  HAZARD MITIGATION METHODOLOGY (HMM)
                            Expand or Collapse
          Why Implement HMM in your Community?
                                              Expand or Collapse
                Exposures During WUI Fires
                                  HMM vs Traditional Hazard Mitigation
                                  WUI Definitions
                                  Structure Survivability in the WUI
                                  Community Survivability in the WUI
                                  Paths forward: Implementing HMM
                                  Communities already implementing HMM
                      How Fire Spreads in the WUI
                                              Expand or Collapse
                How do Structures Survive WUI Fires?
                                  Fire Spread Pathways
                                  Why Exposure Matters, not Parcel Boundary
                                  Hazard from Fuel Agglomeration
                                  Community-scale WUI Fire Hazards
                      Community-Wide Structure- and Parcel-Level Hardening Actions
                                              Expand or Collapse
                How Density Impacts Community
                                  Workflow for HMM Hardening Actions
                                  Structure Hardening for Embers
                                  Parcel Hardening for Fire: the Three R’s
                                  Surrounding Parcel Hazard Mitigation
                                  Primary Parcel Hazard Mitigation
                                  Structure Hardening for Fire
                                  Communities Hardening Actions
                      Hardening Actions: Construction Guidance
                      ContactsStructure Hardening for Embers

Share
  Facebook
                      Linkedin
                      Twitter
                      Email

All structures MUST be hardened for ember exposures.

Research and experience from past WUI fires shows that a majority of structures are ignited by embers. The widespread and unpredictable nature of ember showers means that all structures need to be protected against ember ignitions.

Ember exposures cannot be eliminated or reliably reduced.
	Embers can arrive miles ahead of the wildfire front and cause ignition to homes and property.
	A single vulnerability can result in destroyed structures.
	To reduce ember ignitions of homes, ADUs, and other structures of interest, vulnerabilities on these structures need to be *fully*mitigated.HMM recommends addressing all vulnerabilities unique to each structure. Forty vulnerabilities to ember ignition, and their mitigating actions, have been identified in Table A. Steps should be taken to further mitigate any additional vulnerabilities that may be identified on individual structures.



**Link/expand to Table A**

 
      alt-text-herealt-text-herealt-text-herealt text here

    
    Created July 6, 2023, Updated August 22, 2023 ‹ Workflow for HMM Hardening Actions
              Parcel Hardening for Fire: the Three R’s ›
 HEADQUARTERS
            100 Bureau Drive
              Gaithersburg, MD 20899301-975-2000
            Webmaster | Contact Us | Our Other Offices
        Twitter
            
Facebook
            
LinkedIn
            
Instagram
            
YouTube
            
Giphy
            
RSS Feed
            
Mailing List
                              How are we doing? Feedback

  
  Site Privacy
                      Accessibility
                      Privacy Program
                      Copyrights
                      Vulnerability Disclosure
                      No Fear Act Policy
                      FOIA
                      Environmental Policy
                      Scientific Integrity
                      Information Quality Standards
                      Commerce.gov
                      Science.gov
                      USA.gov
                      Vote.gov