Miami-Dade County NOA - Roof Panels 1

[waytsh]

Can anyone explain to me what exactly a Miami-Dade County Notice of Acceptance is? A Client has asked me to design roof panels for a structure in a high wind zone (not in Florida) and provided this document for the allowable design values. It does contain a table with "Maximum Design Pressures" but these values are significantly higher than what I had seen published for the same panel under the ASTM E-1592 testing. Is the intent of these NOA's for them to be used as allowable design documents? Hope this makes sense what I am asking.

Thanks!

 

[bones206]

Start here:

https://www.miamidade.gov/building/library/brochures/construction-materials.pdf

https://www.miamidade.gov/building/control-forms.asp

 

[JedClampett]

I'm sure someone knows more about this than me, but I'll try. Miami Dade and Broward County are in High Velocity Hurricane Zones (HVHZ) per Florida Building Code. These dial in a whole bunch of requirements, regarding winds, missiles, etc. A lot of it is in regard to residential products but there's commercial and industrial ones, too. But the powers that be realized that just requiring a higher criterion was going to shake out a bunch of amateurs saying their products meet the criteria, and they're back where they started. So they defined a system where the products need to be tested or engineered or both to prove they meet he HVHZ criteria. They give installation instructions and limits These are monitored by Miami Dade County and filed here. These Notices of Acceptances (NOA) expire after a couple of years and have to be renewed. It's actually a very good system.
In your situation you're going to have a problem with your local contractors whining because they don't understand this system (of course in Southeast Florida, they're used to it) and don't know how to comply with it. I've used it in other areas of Florida (like the panhandle) and got pushback. Roofs are particularly difficult. You have to review submittals closely and have inspectors to enforce installation standards.
There's also a statewide system that's somewhat equivalent.

 

[waytsh]

Thanks bones, yes, I had read that information. It is still not clear to me why ASTM E-1592 would state one allowable uplift value and then the Miami-Dade document would state an allowable value more than three times higher. I am not sure how to reconcile the two. Jed, are you saying that there are different installation requirements that are allowing it to achieve the higher capacity? Near as I can tell they are both specifying the same configuration (gauge, clip spacing, decking, etc.) Unless the values stated in the NOA are the values that it needs to be designed for?

 

[bones206]

There may have been two different test protocols performed for each set of values. Maybe there is a safety factor buried somewhere. Not really sure, it's a murky system.

 

[JedClampett]

Jed, are you saying that there are different installation requirements that are allowing it to achieve the higher capacity?

Probably. As an example, I opened this up for a common Butler roof. It looks like they have different attachment zones for the corners, the edges and the field. I'm not super conversant on Butler's "normal" installation, but I doubt it's that sophisticated.
Every NOA has something similar. An analysis (or tests) done by an independent engineer, and installation instructions that correspond to the analysis.

 

[EdStainless]

My daughter lives in Coral Gables.
Now that this is once again a highly desirable area to live in they have gotten super picky about renovation work.
It takes months to get styles and colors approved.
Out of curiosity I called the city and asked about roofing.
Specifically, I asked if the approved (aesthetically) roofing styles all had NOAs.
This was met with a long silence ...
In the end the answer was yes, but they had a tough time answering.
Windows were easier on this count but harder to get approved for looks.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[lexpatrie]

If you install it per the manufacturer's standard details, you get the standard resistance, if you attach it per the NOA it's supposed to resist whatever test pressure that document lists, the NOA probably changes the attachment details versus the standard install. It's a lot like an ESR where the ESR can sometimes modify the manufacturer's installation instructions, add a slope limitation, etc.

 

[a2mfk]

I have been an engineer in Central FL my whole 25 year career, but not much work other than inspections in S FL. Since your client just wants the roof to be designed to the wind speeds for the area of the building, then there is nothing magical about wind pressures in a different area, they are all derived from the same formulas for a given wind speed. It always seemed like some big marketing gimmic, the "High Wind Velocity Zone", like some magical thing happens when you are on 95 driving south and hit the border of Broward.

S FL has always been especially odd when it comes to politics and corruption <shrug>. The Panhandle used to have the opposite,lower levels, and apparently windborne debris did not occur there.

I am probably missing something here....

 

[lexpatrie]

HVHZ - High Velocity Hurricane Zone, as I recall, but I'm being pedantic.