Guide to ASCE 7: Design Loads for Metal Roofs

Looking for an in-depth guide on ASCE 7? In this article, we take a look at ASCE 7, its purpose, and how to get specific calculations for your next metal roofing project.

Successfully designing and installing a metal roof can be a complicated process. Aside from choosing the right materials and ensuring the design is up to standards, you also have to pay attention to various testing requirements. Meeting these requirements and finding accurate testing specs will improve the safety and longevity of your metal roofing project. One of the most important governing standards for metal roofing is the American Society of Civil Engineers (ASCE) 7: Minimum Design Loads and Associated Criteria for Buildings and Other Structures.

At Sheffield Metals International (SMI), we understand how important testing specs are for contractors, designers, and homeowners. With decades of experience in the metal roofing industry providing coils, sheets, and other accessories, we’ve learned that the more information we can provide on our products, the easier it is for customers to get their jobs done.

In this article, we explain:

  • What ASCE 7 is
  • The purpose of ASCE 7
  • ASCE 7 criteria
  • How to get ASCE 7 calculations

We’ll cover these topics and more, going into detail about ASCE 7 and why it matters for your metal roofing project. By the time you’re done reading, you’ll have an overview of ASCE 7 and should understand how to better integrate it into your next job.

What Is ASCE 7: Minimum Design Loads and Associated Criteria for Buildings and Other Structures?

A residential home on a lakefront featuring a standing seam metal roof

The American Society of Civil Engineers (ASCE)is the standard for determining design loads for buildings. It’s widely accepted as the standard to figure out what type of pressure your roof is going to have to meet. While it can be used on both residential and commercial projects, it’s heavily used for commercial applications. There are different versions of the ASCE 7, so you’ll have to match the local code and requirements to that specific version.

ASCE 7 also includes other criteria for measuring the reliability of a metal roof, taking into account aspects like roof zones, geographic location, and building design. One of the most impactful things about ASCE 7, and one of the reasons it’s so universally accepted, is that it merges the testing from the manufacturer with the specific project it’s being used on, producing actionable insights for contractors and designers to utilize.

What Is the Purpose of ASCE 7?

 ASCE 7 is job-specific, meaning that everything taken into account is specific to your unique metal roofing project. This also makes it a one-time calculation. The calculations are only valid for that unique building, and if anything changes, you’ll need to get the calculations done again.

Based on these calculations, you can find the right roofing components and pieces to design and install your metal roof safely and accurately. ASCE 7 gives you access to precise measurements, including a detailed report showing the engineering requirements of the panel you should have based on your building design. This is a critical piece of your project that can help a job go smoothly.

Even if there are no requirements for specific testing, ASCE 7 is a fairly small investment that can provide valuable information for your metal roofing project.

Download the Panel Profile Quick Reference Guide here!

What Criteria is Involved in ASCE 7?

ASCE 7 accounts for multiple factors to create a comprehensive set of specifications for your metal roofing project. Your specific regional conditions and the building’s location will be included, along with the specific design of your roof. A design pressure for a building that’s ten feet off the ground, for example, will be completely different than a building that’s fifty feet off the ground.

 ASCE 7 also focuses on a building’s roof zones: these are different areas of your roof that will receive varying wind pressures because of where they’re located. Typically, there will be at least three different roof zones of a metal roof:

  • Corner zones: These are areas of your roof where two edges meet, which will take the most force of the wind on both sides and the brunt of the impact.
  • Perimeters: Any edge, including eaves and rakes. The perimeters are the second highest areas for wind force on a metal roof.
  • Field area: The inside and central portion of the roof — this area sees the least amount of wind pressure since it’s located away from the edges and corners of the roof.

Roof zones are integral to ASCE 7 criteria because your design dictates how wind will affect different parts of a roof at different speeds. ASCE 7 gives you design calculations for these roof zones based on the pressure they’re going to receive.

Roof zone design pressures will affect installation processes, such as clip spacing. Depending on the design pressure, you’ll have to match your clip spacing to meet the requirements and measurements for each roof zone.

Download the "7 Common Problems That Could Affect Your Metal Roof" infographic!

Are ASCE 7 Specifications Typically Included in Plans from Architects and Designers?

Ideally, ASCE 7 calculations will have already been done and included on the plans for a metal roof by architects and designers. In some cases, however, ASCE 7 specs will not be included, and the contractor will likely have to get their own calculations based on their unique building requirements.

The specifications of the plans usually cover the different criteria that will be used to get ASCE 7 calculations done. It will be the responsibility of the contractor to have the calculations performed.

A qualified metal roofing supplier will typically be partnered with various engineering firms that know exactly what they want when it comes to ASCE 7 testing. If you partner with a company like this, the supplier can work with you to get calculations performed by a state-licensed engineer where your project is located.

As a contractor, it’s essential to know how to get these calculations and ensure they’re accurate.

How Do I Get ASCE 7 Calculations as a Contractor?

A metal roofing consultation

The key to getting job-specific calculations as a contractor is to work with your manufacturer. They have all of the information on your materials, after all, so you’ll need to work with them to get specifics on your products. Calculations need to be based on the testing you have available to you.

A reliable metal roofing supplier will provide in-depth information on your panel profile and give you any specifications you need to get the job done. In some cases, the supplier will work with you to find a third-party company to get your calculations done.

This supplier won’t necessarily work as a middleman communicating your specifications for you, but they can give you a trusted referral. They can set up the meeting, make sure you have all the information required for testing, and make the process as easy as possible.

This way, you can easily get your specifications without having to go searching on your own for reliable testing.

How Do You Accurately Bid On a Project Without Having ASCE 7 Calculations Done?

A green standing seam metal roof in the Coachella Valley Water District

It’s much easier to bid on a project when you already have the calculations done, and they’re included in the plans. If you find the right metal roofing supplier, they’ll be able to give you an engineering cheat sheet that lists out all of their panel profiles, including the assemblies that they were tested with and the different design pressures for various clip spacings.

If the calculations are already done, the supplier may be able to meet those requirements and get you what you need. The more information your supplier can give you, the easier it will be for you to accurately bid on a project.

If you know what requirements you must meet in the different zones, you can review the engineering cheat sheet and match the design pressures provided with the system and assembly you plan to use.

Learn more about roof & wall panel profiles here.

Now, if you don’t yet have your calculations and you’re still bidding on a project, you probably don’t want to spend the money to get testing done. However, those specifications are still critical, so how can you submit an accurate bid before the calculations are complete?

There are ways you can convert design pressures to wind speeds and get a rough estimate of whether the project you’re bidding on can meet specific requirements. You can get a good idea of your design pressure using the mean height of your building, the exposure category it’s in, and the wind speed you need to meet.

While it won’t be exact calculations performed by an engineer, it can give you a decent amount of comfort and allow you to bid confidently on projects.

If you can meet design pressures easily with the panel profiles you have at your disposal, you should be able to meet the actual design calculations when they’re done.

If you’re unsure, it may be time to rethink the project and plan how to move forward.

 How Can I Get ASCE 7 Specifications for My Metal Roofing Project?

In this article, we covered what ASCE 7 is, its purpose, what criteria it includes, and how you can find these calculations for your next metal roofing project. By now, you should have a good idea of ASCE 7 and what it can offer you.

ASCE 7 testing calculations cover a lot of ground, and there are a lot of different criteria that go into the process. If you’re looking for more information on this topic, feel free to check our additional articles on wind uplifts and our accompanying video series on the subject.

If you’re looking to integrate ASCE 7 calculations into your next project, you may be looking for a qualified metal roofing supplier that can get you the information you need. At Sheffield Metals, we help designers, contractors, and homeowners throughout the process.

We can find a third party to help you get your calculations and provide you with the exact information you need to get it done. Reach out today to get in contact with one of the experts on our team and get the specifications you require.

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