Furthermore the roofing designer or specifier sometimes assumes if there is a design wind speed requirement of 90 mph then the roof system must have a 1 90 rating which is not always true at least not for the reason they think maybe for tall buildings or if other factors exist.
Fm 90 roof rating.
The 1 is a designation for a class 1 assembly as designated in test standards 4450 and 4470.
This class addresses both the roof assembly and the roof deck.
I don t do much in regards to projects requiring fm ratings but have been doing some research.
Other factors that affect wind uplift ratings.
When the 6 5 foot wide sheets are used in conjunction with hp xtra fasteners and hpxtra polymer seam plates at 12 inches on center the system qualifies for an fm 1 90 rating over a grade c steel deck.
The class a brand weighs 2 000 grams class b 500 grams and class c 9 1 4 grams.
The numeric designation 60 75 90 etc is the calculated wind uplift pressures with a.
In this situation the fm regional engineer specifies that the roof must have a wind rating such as 1 60 1 75 or 1 90.
The second most common mistake a designer or specifier may make is concluding that wind speed is.
Requirement of 90 mph then the roof system must have a 1 90 rating which is not always true at least not for the reason they think maybe for tall buildings or if other factors exist.
Fm wind rating specified only.
For example the fm i 90 was a 90 mph wind rating.
Failure is defined as the point where the roof deck.
The brands consist of an ignited wood lattice placed directly on top of the test specimen.
Carlisle syntec systems has introduced its 6 5 foot sure tough reinforced epdm.
Sometimes a roofing designer will assume that a design wind speedrequirement of 90 mph then the roof system rating will be 1 90.
Take the guesswork out of an fm approved roof roofnav can take the guesswork out of configuring an fm approved roofing system leaving you to focus on what matters most.
I ve come to discover that the number 90 has nothing to do with miles per hour but actually has to do with the wind uplift pressure where as i 90 is 90 lbs per sq ft i believe.
It is important to note that fm global lists approvals using ratings of 1 60.
Designed to help roofing professionals roofnav provides easy access to the most up to date fm approved roofing related information and related installation.
Both are burn through tests and the ultimate roof systems rating is the lowest of the three tests.
Epdm can meet fm 1 90 ratings.
We would like to show you a description here but the site won t allow us.
This may be all that is specified.
