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Re: Standing Seam Metal Roofing Wind Uplift Calculations

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Oshin, 
To be clear, I assume that:
1) you are referring to a "structural" standing seam roof and not an
Architectural roof cladding with a protruding rib at side laps;
2) you are a specifying engineer for a project and not asking for research
basis purposes; 
3) this is a North American application.

Lets also make a distinction between what is REQUIRED by code and what is
OPTIONAL as a performance qualification. I am not aware of any code that
requires either FM or UL roof assembly ratings for a standing seam roof
(anybody in tornado zones with more information?).

Design standards: design/analysis methods for strength and service
AISI: North American Specification for the Design of Cold-Formed Steel
Structural Members. AISI produces a design guide for standing seam roofs.
Panel capacity is the tip of the ice-berg.

That is probably the real answer to your question. Everything else gets
mixed into the conversation on a regular basis.

Third Party (Insurance company) guidance: performance qualifications -
strength and service
Factory Mutual: FM I-60 and I-90 are based on tests to the FM Standard 4470.
Underwriter's Laboratories: UL Class 15, 30 and 60 are based on the UL 580
test protocol. 
Note that these do NOT relate to specific wind speeds or pressures. These
qualify ASSEMBLIES; the panels, fasteners, clips and sub-structure as
assembled and may have minimum conditions (e.g. purlin spacing and
thickness, stainless steel fasteners, panel thickness and steel grade, etc.
to qualify). FM insurance premium basis will occasionally require higher
design loads than required by the authority having jurisdiction.

A manufacturer must have had the tests performed with their product and
assembly in order to be able to claim compliance to these qualifications.
Claims of comparable products and assemblies aren't sufficient.

Independent Standards:
ASTM E 1592 Standard Test Method for Structural Performance of Sheet Metal
Roof and Siding Systems by Uniform Static Air Pressure Difference.
Tests the assembly. Knowledgeable manufacturers will have done this.
Mandatory compliance under code specified conditions.

Manufacturer guidance (e.g. MBMA): see AISI
MBMA's Low-Rise Building Manual does not have a performance specification
and, as with the building codes, simply advises the designer to meet the
strength and service requirements based on the applicable building code and
the customer requirements - which may include insurance carrier acceptance
(see above). 

If the manufacturer hasn't done these tests, find another manufacturer
because the cost probably isn't going to be available in the project budget.

Regards 
Paul 

> From: "Oshin Tosounian" <oshin(--nospam--at)sdgseinc.com>
> To: <seaint(--nospam--at)seaint.org>
> Subject: Standing Seam Metal Roofing Wind Uplift Calculations

> Are there any standards or guidelines for the wind uplift design of standing
> seam metal roofing?

> Oshin Tosounian, S.E. 


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