CONCLUSIONS AND RECOMMENDATIONS
to create a structural system beneath the roof covering and to establish a load path from metal covering all the way down to foundation. Conclusion PR-25 Even homes that were undamaged during the hurricanes may be susceptible to future wind and seismic events: The MAT observed many homes that experienced little to no structural damage but remain vulnerable to the effects of high winds. In most cases, the connections between the structural members and a lack of protection for glazed openings are the weakest links in the load path and are vulnerable to failure. Recommendation PR-25. Homeowners should consider evaluating and retrofitting existing homes for wind and seismic vulnerabilities. Homeowners should consider hiring design professionals to evaluate the existing roof structure to determine if can carry at least 75 percent of the design load. If it cannot, they should consider performing wind retrofits with continuous load path systems in accordance with Repair and Replacement of Wood Residential Roof Covering Systems (FEMA PR-RA6, Appendix D) and Wind Retrofit Guide for Residential Buildings (FEMA 2010). Homeowners can also consider wind retrofit techniques set forth for the different protection levels of FEMA P-804 to holistically improve the hazard resistance of homes. Conclusion PR-26 Roof Penetrations often caused water intrusion: Where roof penetrations existed, such as at utility service masts, localized roof failure and water intrusion often occurred. Recommendation PR-26. Avoid rooftop penetrations whenever possible. Do not penetrate the roof whenever possible whenever attaching rooftop equipment. Consider use of design guidance found in Rooftop Equipment Maintenance and Attachment in High-Wind Regions (FEMA PR-RA1, Appendix D) when attaching rooftop equipment or service utility masts. Conclusion PR-27 It is common practice to use prescriptive home designs in residential construction and permitted by the building code: The MAT obtained prescriptive design plans developed by the Commonwealth of Puerto Rico by PRDOH and from municipalities around the island. The designs included many hazard-resistant design approaches developed in response to Hurricane Georges in 1998 and provided details to allow a homeowner or contractor to successfully construct a home compliant with the 1997 UBC, which had been adopted after Hurricane Georges. However, availability and access to the plans may have been limited, and no formal program was identified that supported the distribution and use of these designs. Where residential construction appeared to perform well, the homes had many of the features observed in the prescriptive designs, but the homes could not be verified as having been constructed to the prescriptive plans.
HURRICANES IRMA AND MARIA IN PUERTO RICO
MITIGATION ASSESSMENT TEAM REPORT
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