In recent editions, Coastal Connection has discussed
recommendations for roof covering reinforcement and for opening
protection found in the Institute for Business and Home Safety's
report "Hurricane
Ike: Nature's Force vs. Structural Strength". In this issue, we
take up the IBHS report's "third tier" of recommended upgrades:
measures to strengthen the framing elements and connections that
hold the entire house structure to its foundation, resisting the
uplift forces of hurricane-strength winds.
IBHS has made these measures a third priority, not because
they're less important, but because they're harder to accomplish
with a limited budget, the Hurricane Ike report explains: "The
third tier is the hardest and most expensive since it involves
strengthening the connections of the roof to the walls and the
walls to the foundations. These retrofits typically will involve
significant disruption to the home and its occupants and can be
most economical and practical when they are part of a major
remodeling job or when rebuilding after a flood or hurricane has
damaged the exterior walls."
One difficulty is that the uplift path can be tricky to analyze,
and specifying effective improvements can involve specialized
knowledge. IBHS recommends hiring an engineer to specify connection
details for remodeled parts of the house, or to determine what
connection upgrades are appropriate for existing framing.
The State of Florida has adopted code provisions that require
roof connection upgrades to be included in some re-roofing jobs.
Advice on assessing roof-to-wall connections is posted at this
"
Hurricane
Retrofit Guide" website. And for more information, take a look
at Coastal Contractor's November, 2008, story, "
Strengthening
Roof-to-Wall Connections," by Richard Reynolds.