Closeup of a grey standing seam metal roof with nice houses and trees in the background.

Jun 11, 2021

Standing Seam Metal Roof Installation: Snap Lock vs Mechanically Seamed Panels

A metal roofing system consists of metal panels cut to exact sizes that are designed to lock together. Metal roofing systems use exposed or concealed fasteners, which connect the metal to the roof deck. A standing seam metal roof uses concealed fasteners, which are reinforced and protected from the elements while allowing for roof expansion and contraction, which increases the roof’s longevity.

Standing seam metal roofs are a premium product with outstanding curb appeal. Once you’ve made the decision to move forward with a high-quality standing seam metal roof for your home, there are a couple of concealed fastener installation methods to choose from: snap lock or mechanically seamed panels. The method of installation can affect the price and performance of your new metal roof.

What is Snap Lock?

A snap lock standing seam metal roof panel has a male and female leg that snap together. The panel is attached to the roof deck using clips that fasten underneath the panel and out of view, keeping the roof clean and smooth looking. Since the panels simply snap together, the installation takes less specialized tools and less labor hours, which can result in a more affordable installation in comparison to mechanically seamed metal roofs.

Since a snap lock installation method is simpler than mechanical seams it may be tempting to DIY your roof installation, but it is still recommended to have an experienced metal roofer complete your roofing project. The biggest risk to a metal roof is not actually weather, but poor installation, which gives moisture the opportunity to penetrate the seams. If the attic is improperly vented, rising air can heat any water that has infiltrated the seams and cause damage to the roof. However, when professionally installed, a snap lock standing seam metal roof can last decades with minimal maintenance.

Closeup of a grey/brown standing seam metal roof.

Disadvantages of Snap Lock Panels

Standing seam metal roofs are known for being very weathertight as they do not have exposed fasteners that can allow for possible water penetration; however, a snap lock metal roof is less weathertight than a mechanically seamed metal roof. Mechanically seamed panels are secured together so tightly that there is no room for water to come through.

Snap lock is not the right metal roofing choice if you have an incredibly low sloped or flat roof as these panels cannot be used on a roof that is less than a 3:12 pitch. Water accumulates more easily on lower sloped and flat roofs, making the chance of leaks greater. If your roof pitch is 1:12 or greater, a double lock mechanically fastened standing seam metal roof is a better solution.

What is a Mechanically Seamed Panel?

Mechanically seamed standing seam metal roof panels utilize a concealed fastener system with a male and female leg. The clips used in this metal roofing system are designed to line up with one another so that they can be locked together by a mechanical or hand seamer. Mechanically seamed roofs can use a single lock or a double lock. The way that the panels are fastened together makes the roof more weather resistant and less likely to have issues with leaks.

Single Lock vs Double Lock Standing Seam Metal Roof Systems

Single lock and double lock simply describe how the mechanically seamed panels are installed. In a single lock system, the panel is folded once at 90 degrees. A single lock system is best suited for more mild climates and is easier to install than a double lock system. If you live in an area with heavy rain and snowfall, a double lock mechanical seal is best for your roof.

In a double lock system, seams are folded twice at 180 degrees and every clip on each panel needs to be seamed by hand, which takes more labor and affects installation costs. The additional lock keeps the panels from coming undone and are suitable for extremely low sloped roofs.

Disadvantages of Mechanical Seams

The very thing that makes mechanically seamed standing seam metal roofs so weathertight and durable can become a disadvantage if the roof needs to be repaired. If a panel is somehow damaged badly enough that it needs to be replaced, it may be more difficult to perform repairs on a mechanically seamed roof than a snap lock metal roof because the panel needs to be unseamed before it can be removed.

How to Choose your Standing Seam Metal Roof Installation Technique

Keep in mind that when you choose a standing seam metal roof, you are choosing to invest in a high quality, premium product that stands the test of time. It’s important to consider the slope of your roof, the weather patterns in the area where you live, the location of your home, and your budget. No matter the method of installation you choose, you are receiving a high-end metal roof. Whether you choose a snap lock standing seam metal roof or a mechanically seamed standing seam metal roof, differences in appearance after the installation are virtually unnoticeable. Call the experts at Gravity Metal Roofing today at 844.352.7663 to schedule a consultation to discuss your metal roofing project.