I believe hurricane force winds effects structures the higher they are. Probably the reason for so many single floored structures.
Darius,
Let me know if you want to teach a class on Wind Mitigation in Orlando(or maybe York).
Call me on my cell. 321-626-8153
John, you have all the subtlety of a sledgehammer! So Darius has experience in teaching a class, but it doesn’t mean that he is right!
Darius, I checked the publications from, Bill York (Pg 46 from his resource guide dated Jan 31 2012 ) and the Inspection depot training manual ( Pg 225 13.3.1.(5) from 2011) both say substantially the same thing: From the lowest supporting member to the highest grade. Both show exactly the same picture to support it too. So what documentation do you have to the contrary?
Also, where does it mention mean roof height in the 1802? The 1802 only addresses the number of stories, it makes no allowance for height at all.
Thomas, height plays a major part in windspeed, With maximum sustained winds usually measured at 33’ above grade.
This train of thought is what I believe should be the current thinking on determining number of stories. Unfortunately, that is not what’s in the current training manuals. I assume most of this came from York Consulting because the same verbiage and photos are used on the subject.
Darius, I would go to one of your classes if you wanted to pursue that direction. I know you are well respected in this field, and would have a good following.
Just goes to show why there needs to be clarification and standardization
I don’t really teach classes but do train all of our inspectors in several states. I am also a participating attendee providing recommendations and building consensus through the public rule development process on the OIR form and definitions.
I have been involved with Wind Mitigation Inspections and the design development of mitigation recommendations and programs both on a national level and through advisory boards in several states. You are correct the form does not indicate how this is determined. My recommendation is that it should be based on something that is easy to verify and simple to understand.
If we are to be absolutely correct the measurement would be based on “mean grade”. This calculated by dividing the sum of the lowest and highest grade measurements by the number 2. Example say you have 4 feet on one side and 10 feet on another (4 + 10/ 2 = 7). But then you would also have to consider the highest and lowest points of the roof divided by 2. To make it easier we use worst case scenario just use the lowest grade. If the main floor (pilings) or lower floor (living) has an exposure greater than 7 feet it adds a story. Simple and easy to verify from photos, In 18 years I have never had an owner or underwriter challenge this or state it was wrong. The problem with using the higher grade is that the room for error is higher (gets down to inches) and you may actually call some 2 story homes 1 story and it would be very hard to determine this from photos unless you guys want to start taking photos of a measuring tape against the grade and lower floor, didn’t think so. So for DSCI we choose to err on the side of KISS and easily verifiable from the elevation photos.
Asking someone about teaching a class is not the same as having them teach the class. He will not be teaching the class, but we had a great conversation.
That being said; in something everyone is my master and from that I may learn from him.
I do not agree with how some teach wind mitigation and I am sure they do not agree with everything I do either. I will continue to work on an updated class, you just may be stuck with me at the conference. 
I am curious do most property appraiser sites list the number of floors in a home. If so would that not be a safe way then to qualify your answer. I mean should we really be going against what the property appraiser site has the home listed as the number of stories.
Absolutely not, is that what you do? Completely different.
I have never had a case where it wasn’t obvious. Lucky me I guess I
PA only lists habitable floors of the home, not the structure.
Ahhh I was not even sure what they listed and if each county was the same or not. Just a thought. Thanks for clarifying 
Did a Type III wind mit today with an example of a building with a partially enclosed parking garage. Front of building is 8 stories, and rear is 9 stories…selection on form is 8 stories. The previous WM was done by an engineer in 2010 and listed the stories as 9, and incorrectly submitted on the 1802 form (wrong form).
The 7 foot threshold is applicable for homes built on stilts, I have not come across any wind mitigation training that addresses basements. The following is lifted from the Florida, and International Building Code and is what I use to determine # of stories when the home has a basement.
**Story Above Grade Plane.
**Any story having its finished floor above grade plane, except that a basement shall be considered as a story above grade plane where the finished surface of the floor above the basement meets any one of the following:
- Is more than 6 feet above grade plane
- is more than 6 feet above finished ground level for more than 50 percent of the total building perimeter.
- Is more than 12 feet above finished ground level at any point