Expansion & Contraction in Metal Roofing

How Much do Metals Expand?

The thermal expansion coefficient of a metal determines how much it expands and contracts with temperature changes. In metal roofing, different materials respond differently to temperature fluctuations, affecting installation methods and performance. Over a 20ft run of material, with a temperature swing of 100°F, this is how much the following materials expand:

• Steel (Galvanized or Galvalume): .16″
• Aluminum: .31″
• Copper: .22″

You can see why longer panel runs require special attention regarding expansion and contraction. While steel does not expand nearly as much as aluminum, a good looking installation can turn into a disaster if you do not consider expansion.

How does this apply to clips & cleats?

For a low pitched roof, using fixed cleats in the center of the panel and expansion cleats toward the ridge and eave is good practice.

 

 

For a medium pitched roof, you want to move the fixed cleats closer to the ridge while the expansion should fall with gravity and expand toward the eave.

 

 

For steep pitches, get those fixed cleats all the way up near the ridge and use expansion through the panel center and down to the eaves. Be sure to allow space around your eaves edge where it hooks onto the trim.

1″ or 1.5″ Fixed Cleats

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1″ Expansion Cleats

Available Here

 

5 Key Expansion Takeaways for Metal Roofing

1. Aluminum expands twice as much as steel, requiring more careful design for expansion joints. If you are working aluminum on the coast, you need to be aware of this. Copper falls between aluminum and steel.
2. Temperature when installing matters! If you are installing in the coldest climate, then you must allow for expansion. If installing in the warmest, then you need to allow for contraction.
3. Expansion cleats should be incorporated into the roof designs that have panel lengths of 20ft or longer. 
4. Expansion will tend to follow gravity, so use fixed cleats toward the ridge of the roof and expansion cleats toward the middle and the eave.
5. Roof surface temperatures change more drastically than ambient outdoor temperature. Do not underestimate your roof surface’s ability to expand and contract. 

Understanding these differences is vital when choosing the right material and installation method to ensure longevity and structural integrity in metal roofing systems.

Expansion and Contraction Must Be Considered When Installing a Standing Seam Metal Roof

Metal expands when heated and contracts when cooled, meaning that a roof panel can shift slightly throughout the day and across seasons. If the roof is not designed to accommodate this movement, issues such as panel distortion, fastener failure, or oil canning (visible waviness) can occur. This is particularly important for long panel runs, where the movement is more pronounced, and improper installation could lead to structural stress or premature wear.

To mitigate these risks, we use specialized clips and floating fasteners that allow the panels to move without causing damage. Additionally, proper spacing and seam design ensure that thermal movement is evenly distributed across the roof. Without these considerations, the roof may experience buckling, leaks, or fastener breakage, ultimately compromising its longevity and performance. By understanding and accounting for thermal expansion and contraction, homeowners and contractors can ensure a durable, long-lasting, and efficient standing seam metal roof.

 

Another item that considers expansion & contraction

The Freund Notcher is a slotted punch tool that will allow space for the metal to expand and contract but still be securely held.