From architects, to contractors, to manufacturers in the metal roofing industry: It’s important to know the ins and outs of what makes a metal roofing system perform to the best of its ability.
The best way to accomplish this is by familiarizing yourself with the common industry standards and tests metal roofing goes through to ensure the success of a system. Once you know the industry standards, you’ll be able to reassure your customers that their metal roof is tested and proven to perform and protect in harsh weather conditions.
We want to be honest with you: There are a lot of metal roofing standards and they tend to be complex, which might confuse even the most seasoned person in the industry. But here at Sheffield Metals, we want to simplify this topic to help you better understand:
- The importance of metal roofing industry standards
- Who does the testing for metal roofing standards
- How the tests and standards vary depending on location, job type, and a variety of other factors
- Common standards in metal roofing and how the products are tested
The Importance of Metal Roofing Industry Standards
The reason that standards and testing exist can be summed up with one word: TRUST. Consumers need to be able to trust the products and services they spend their money on and that it will live up to expectations and solve the problem it’s designed to fix. This is why standards exist for nearly everything; from food or medicine, to paper products, to electrical wires, and far beyond.
So why does it matter for metal roofing?
Standards and testing ensure that a metal roofing system can protect a building or home in both regular and extreme weather conditions while still meeting building and construction codes of the industry and local municipalities.
- Provide peace of mind to suppliers, contractors, architects, and consumers alike by proving products will perform instead of saying, “Just take our word for it.”
- Keep in mind, many consumers choose to buy metal roofing because it protects their most valuable assets, such as loved ones, photos, files, investments, etc.
- Stop untrustworthy manufacturers from selling low-grade products that could easily fail or cause problems.
- Put accountability for product quality (both good and bad) in the hands of the manufacturer.
Who Does the Testing For Metal Roofing Standards?
What’s great about the testing for metal roofing is that it’s tested and rated by independent businesses and organizations that have no stake in one specific industry and therefore can provide a trustworthy and honest analysis. Each standard company provides the standards and specifications for products and materials far beyond just roofing. In other words, they create testing protocol that best measures product performance in real world scenarios.
In metal roofing, there are three major companies that provide the testing standards:
While these companies outline the parameters of how products will be rated based on their performance, they don’t actually perform the testing. Instead, a third-party testing facility performs the test and usually, a representative from one of these standards companies is present to report the findings and provide the final results and/or rating. Just like with the test standard companies, the testing facilities only perform and provide the results; their main concern is that they perform the test accurately to the test standard and not how the product actually performs during the test.
Industry Standards & Testing for Engineered Systems
Before we go through some of the common industry standards for metal roofing systems, it’s important to know that these standards and tests can and will differ depending on geography and building type. It’s impossible to account for every standard that exists because one or more will either be missing or not applicable in a given geographic location.
For example, a building in a hurricane zone in Florida will require different test standards than a building in rural Kentucky, which is why there are multiple test standards that may sound similar but are actually very different. Let’s look at wind uplift resistance, which can be tested according to UL 580, UL 1897, TAS 125, and ASTM E1592 standards, just to name a few. While they all test for wind uplift resistance, some tests are more stringent, require multiple specimen examples to be tested, depend on the type of structure it’s installed on, or test to higher standards than others do. This is the same for impact resistance, water penetration, and most other test standards.
Additionally, commercial and residential metal roofing differ when it comes to standards, even with structures in the same geographic location. Commercial projects have more stringent requirements and must meet the standards set forth by the industry. But residential projects are a little different, as they are more focused on adhering to local building codes and having the correct permits, which are available and able to be pulled by a municipality’s Building Department. It’s worth noting that all roofs have minimum requirements per municipality or Building Department, and even some architects may require different standards that specified products must meet as well. For example, sometimes ASCE 7 is specified and requires an engineer to validate uplift requirements and load exerted on a roof.
In other words, the required tests and standards just depend on the project.
If you’re unsure about the standards that need to be adhered to where you are installing or specifying a metal roofing project, strike up a conversation with your manufacturer or supplier. They will be able to answer your questions and give you a more comprehensive scope of what ratings, standards, or tests a product adheres to and therefore must be used for a metal roofing project in a given area.
UL 580 / UL 1897 – Standard for Tests for Uplift Resistance of Roof Assemblies
The UL 580 standard tests the uplift wind resistance of a metal roofing system, including the panels, accessories (clips, underlayment, and fasteners), and structural support frame.
A small-scale (typically 10×10 ft.) sample of roofing material is installed on the testing platform. The edges are then sealed with closely spaced fasteners.
This pass or fail test is done in three UL 580 sequences and then turns into a UL 1897 if it can go beyond Class 90 and tests until the system fails:
- UL 580 Class 30
- UL 580 Class 60
- UL 580 Class 90 (best)
- UL 1897 test (maintains a positive pressure and increases in negative pressure usually in increments of 15 PSF until the system fails)
- Keep in mind: This is the same system being tested throughout all sequences, so new specimens are not used as the test progresses
Each of these sequences consists of five phases:
- Phase 1: 5 minutes of negative pressure (measured in pounds per square feet, or PSF)
- Phase 2: 5 minutes of negative and positive pressure
- Phase 3: 60 minutes of cyclic (oscillating) negative and positive pressure
- Phase 4: 5 minutes of negative pressure
- Phase 5: 5 minutes of negative and positive pressure
For an example of the pass or fail results, check out the UL 580 test report for SMI’s 1.5” SnapLock 550.
ASTM E1680 – Standard Test Method for Rate of Air Leakage Through Exterior Metal Roof Panel Systems
According to the ASTM E1680 standard,
“This test method covers the determination of the resistance of exterior metal roof panel systems to air infiltration resulting from either positive or negative air pressure differences … This test method is intended to measure only the air leakage associated with the field of the roof, including the panel side laps and structural connections; it does not include leakage at the openings or perimeter or any other details.
Like UL 580, ASTM E1680 does the testing using a small scale roofing system, including panels, clips, and a support frame.
The test consists of six separate preload pressures (three complete cycles of preload pressures) all at a specific pressure (in PSF), followed by measurement of the air infiltration and air exfiltration through the panel, which is measured in cubic feet per minute (CFM).
- Positive preload
- Negative preload
- Positive preload
- Negative preload
- Positive preload
- Negative preload
- Air infiltration measurement
- Air exfiltration measurement
Based on the measurement collected in the final two steps, you will be able to determine the rate at which air is expected to leak through properly installed panels.
ASTM E1646 – Standard Test Method for Water Penetration of Exterior Metal Roof Panel Systems by Uniform Static Air Pressure Difference
The standard for water penetration, ASTM E1646, is similar to the air infiltration test. This is another pass or fail test. According to the scope of the standards:
“This test method covers the determination of the resistance of exterior metal roof panel systems to water penetration when water is applied to the outdoor face simultaneously with a static air pressure at the outdoor face higher than the pressure at the indoor face, that is, positive pressure … This test method is applicable to any roof area and is intended to measure only the water penetration associated with the field of roof including panel side laps and structural connections. It does not include leakage at openings or perimeter or any other details.”
After the pre-determined air pressure is reached, water is sprayed on the panels for a duration of 15 minutes. The amount of ponded water is determined and then the amount of water infiltration through the tested panel is measured.
ASTM E2140 – Standard Test Method for Water Penetration of Metal Roof Panel Systems by Static Water Pressure Head
ASTM E2140 is another water penetration test evaluating the resistance of roof panels, sideseams, endlaps, and roof plane penetrations to water submersion. According to the standard’s scope, “This laboratory test method covers the determination of the resistance to water penetration of exterior metal roof panel system sideseams, endlaps, and roof plane penetrations when a specified static water pressure head is applied to the outside face of the roof panel.”
During this test, the roof panel system is completely submerged under water to test its ability as a water barrier. This test method is intended to evaluate water-barrier (not water-shedding) roof system joints and details. These systems are also referred to as hydrostatic roof systems, or roofing with a pitch below 2/12.
UL 790 – Standard Test Methods for Fire Tests of Roof Coverings
Arguably one of the most important tests on a metal roofing system is its resistance to combustion and/or catching on fire. According to UL’s Standard Catalog,
“These requirements cover the measurement of the relative fire characteristics of roof coverings exposed to simulated fire sources originating from outside a building on which the coverings are installed. They are applicable to roof coverings intended for installation on either combustible or noncombustible roof decks when the roof coverings are applied as intended.”
After testing has been completed, materials can be given one of three classes of fire ratings:
- Class A – “Roof coverings are effective against severe fire test exposures. Under such exposures, roof coverings of this class afford a high degree of fire protection to the roof deck, do not slip from position, and are not expected to produce flying brands.”
- Class B – “Roof coverings are effective against moderate fire test exposures. Under such exposures, roof coverings of this class afford a moderate degree of fire protection to the roof deck, do not slip from position, and are not expected to produce flying brands.”
- Class C – “Roof coverings are effective against light fire test exposures. Under such exposures, roof coverings of this class afford a light degree of fire protection to the roof deck, do not slip from position, and are not expected to produce flying brands.”
Most, if not all, metal roofing and wall systems are Class A fire-rated and noncombustible, making it the most resistant to catching on fire.
UL 2218 – Standard for Impact Resistance of Prepared Roof Covering Materials
The industry guideline UL 2218 exists to test a metal panel’s resistance to puncturing or failing when it comes into contact with items, such as hail or other small debris.
The method of testing “provides impact resistance data for the evaluation of prepared roof covering materials…The test evaluates the effect of impact from a steel ball at locations on the assembly selected to be most vulnerable, such as (but not limited to) edges, corners, unsupported sections, and joints.”
Four steel balls of different sizes are dropped from varying heights onto the metal panels (see photo for parameters). The panels are then evaluated to see if punctures or other failures have occurred.
Rating is determined on a scale from Class 1 to 4, with Class 4 being the toughest and least likely to fail when in contact with objects.
Industry Standards & Testing for Paint Specifications
Metal roofing paint systems come with their own standards and testing to ensure success of a paint system. We won’t dive too deep into these standards, but just know that there are a lot of them and are the responsibility of the paint company, such as Valspar or PPG, to have tested before it’s ever coated on a metal coil.
Metal roofing paint systems endure stringent testing, like the natural outdoor exposure test in the photo, to ensure the paint system stands up to chalking, fading, chipping, peeling, and other overall failures.
For example, a standard two-coat Kynar/Hylar paint system (PVDF) typically adheres to the following standards set forth by ASTM:
- Accelerated Weathering – ASTM G23
- Salt Spray – ASTM B117
- Humidity – ASTM D2247
- Formability – ASTM D3359
- Pencil Hardness – ASTM D3363
- Specular Gloss – ASTM D523
- Impact Resistance – ASTM D2794
- Abrasion Resistance – ASTM D968
- Tunnel Test – ASTM E84
- Acid Resistance – ASTM D Procedure 72
In other words, the paint goes through a lot of testing to make sure it doesn’t crack, chalk, fade, peel, or succumb to any other damage prematurely. All of these tests are why many paint manufacturers guarantee their Kynar or Hylar products with lengthy metal roofing and wall system paint warranties. If you ever have questions about the testing that goes into a panel’s given paint system, contact the manufacturer or the paint company that produced the coating.
Final Thoughts on Metal Roof Testing & Standards
Remember, there are many other standards, tests, codes, and regional requirements that apply to metal roofing and wall systems. But the ones we outlined are a good representation of common standards and testing that currently exist in the industry.
At Sheffield Metals, we know how important it is to maintain customer trust, part of which comes from being able to talk through and explain how their metal roof will perform in certain situations.
Get ahead of these questions and contact us today to speak with one of our technical representatives.