What is the safety factor on wind rating in Texas if my structure is rated to 105 mph?

Understand that when dealing with wind, a 105mph rating and safety factor may not be quite what you think they are.

the forces created during 105 mph rated structure allow for gusts and sustained winds that exceed 105 mph for at least 60 seconds. That is literally what your factor of safety is for. In this case, the factor of safety would be between 1.5–2.5. That would you possible protection up to about 140mph in a 3 second gust and about 115–120mph in a 60 second sustained gust.

Keep in mind that for every 5 mph increase major problems start creeping into your scenario. You need to remember that this doesn’t reflect how well the structure is attached to the ground or if local terrain/ buildings are magnifying the wind.

That original number is where the engineers who designed it feel that a normal user, without special knowledge, can safely use the structure under conditions which may occur at those wind speeds.