I am sure this has been discussed before but I am a newbie to the TowerTalk
In applying for a building permit with my city, they told me "it needs to be
rated for 90 MPH with 1/2 inch radial ice". I asked him what standard he was
referring to and he referred me to the latest IBC Section 3108.4. This spec ,
in turn, refers to EIA/TIA 222-E. EIA/TIA 222 g has a windload map that that
, indeed, confirms the 90 mph requirement. However, if I am reading it
correctly, it is referring to 3 second gust speed. It, in turn, includes a
for converting 3 second gust speed to "Fastest-Mile (MPH) Speed. The chart
indicates that 90 mph (3 second gust) corresponds to 75 MPH "fastest-MPH speed".
Setting aside for a minute the radial ice issue, does this mean that that the
70 MPH rating I get from a tower manufacturer like US Tower really
corresponds the higher 3 second gust speed rating as required by the
Or is this just wishful thinking?
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