At 21:58 1/16/01 +0000, alsopb wrote:
>Just for curiosity, how many FLA homes can withstand 110MPH winds? I
>certainly wouldn't care if my tower stayed up, if the house didn't.
>
>There was a documentary on TV after the last big hurricane down there
>showing how many houses failed in much less than 110MPH winds. It
>seems that the development houses ignored most of the specs needed to
>keep the roof on their cinder block pride and joys.
>
>de Brian/K3KO
"Fine Homebuilding Magazine" had an article that examined the failure modes
of a lot of FL houses after hurricane Andrew.
Some of the damage was precipitated (no pun intended) by the rain that
accompanied the wind. When roof membranes are penetrated, the water swells
the underlying roof sheathing and, especially in the case of OSB sheathing
and staples, cuts the wood fibers under the fasteners. This allows the
sheathing to be more easily detached from the roof framing.
As a result, Dade country banned the use of QSB and staples in new
construction.
Gable roofs with overhangs are particularly bad as they catch the wind such
that the sheathing on the overhang detaches and this begins the domino
effect. The sheathing comes off, this reduces the shear strength of the
roof and allows the wind into the attic, this pops off more sheathing, the
roof joists or trusses begins to collapse sideways?..
In short, the wind (hurricane strength) doesn't 'blow down' houses, it
blows them apart.
Wes N7WS
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