Standing seam roofing panels have become relatively popular for both residential and commercial buildings, mainly due to their aesthetics, adequate durability and longevity. Virtually every roofing contractor suggests their clients choose standing seam panels, but there is still a fierce debate around the connection technology. In this article we will analyze whether snap lock is a better, solution than mechanical lock, and if so, what is the reason for this advantage. We will analyze the issue objectively, because as a sheet metal roofing producer we offer both solutions.
Standing seam metal roofs consist of metal panels that run vertically from the ridge to the eaves of the roof. However, the panels have to be connected to each other with something, and in addition, this has to be done in a way that ensures the maximum level of airtightness so that water does not penetrate under the roof plane, which could lead to the development of the very dangerous mold in the attic. So far, the best solution to this problem has turned out to be the development of standing seams, thanks to which, the gaps between the curved sheets are above the plane of the roof, and in addition, they are often directed downward.
Standing seam roofing panels have been produced for about 70 years, and so far, in the vast majority of cases, this joint technology has proven to be an excellent solution.
One of the two most popular ways of joining roofing sheets together is snap lock. This type of connection consists of two prepared edges – each panel has a male and female leg, which snap together when enough pressure is applied.The clips clamp together while leaving a slight space on each side for the metal to contract and expand as the ambient temperature changes.
From an installation perspective, snap lock systems are much more convenient for roofing contractors – they require less precision, and the whole process is also up to 25% faster than with mechanical lock, which of course reduces costs. On the other hand, snap lock seams should be used on roofs with a pitch of 3:12 or greater to ensure better drainage.
Mechanical lock standing seam roofing panels, also known as mechanically seamed panels, require the use of a specialized seaming machine to fold and seal the panels seams after they are placed on the roof structure. There are two basic types of mechanical locks – single lock (90-degree seam) and double lock (180-degree seam). Double lock is much more popular, because for virtually the same price and with a similar amount of work you can get a much stronger joint that can handle harsher weather conditions and will last longer.
Mechanical lock roofing offers better durability, but this comes at the expense of a more difficult and time-consuming installation.In some cases, mechanical seams are also the only possible solution – this is the case, for example, with roofs with slopes as low as 0.5:12, whose water drainage could create suboptimal conditions for snap lock. Theoretically speaking, properly prepared mechanical lock roofing panels can withstand even standing water conditions, although we strongly advise against such a method of roof operation.
In terms of speed and ease of installation, snap lock panels have a definite advantage over mechanical lock – male and female legs join together like plastic blocks, requiring only a rubber mallet to press the pieces together properly.
The use of snap lock speeds up installation by about 20-30%, while reducing the cost of roof installation by up to 15%. The lack of the need for specialized tools and the relative simplicity of the entire process of putting the roof together also make amateur installation of the roof possible, although we recommend it only for those who are relatively comfortable with it.
As a rule, mechanical lock systems offer better sealing capabilities compared to snap lock systems. Mechanically seamed joints provide a much better barrier to water – some roofing contractors use an extra layer of adhesive between the sheets, which provides better performance even than nailed asphalt shingles.
Snap lock roofing panels also offer good watertightness, but one must be aware of their susceptibility to water penetration. For this reason, it is necessary to install them at a higher angle, optimally no less than 14°.
Both snap lock and mechanical lock roofing panels look very good – if installed correctly, it is possible to achieve an aesthetically pleasing, modern plane, and the connection technology does not matter much. However, let’s point out that mechanical lock panels will have less visible connections, so they may look a little better.
Much greater differences exist in terms of material – Kynar coated steel will look quite different from galvalume or copper.
Mechanical lock panels are often considered more durable due to their tightly seamed joints. The mechanical seaming process enhances the roof’s ability to withstand thermal expansion and contraction, reducing the likelihood of seam separation over time. This can be particularly beneficial in climates with significant temperature variations, where metal movement can stress the roofing system.
Snap lock panels, while durable, may experience issues related to thermal movement if not installed correctly. The snap mechanism can potentially disengage over time under extreme conditions, leading to leaks or panel misalignment. Regular inspections and maintenance can mitigate these risks, but mechanical lock systems inherently offer greater long-term reliability.
As a general rule of thumb, you can assume that mechanical seams are more durable, but you shouldn’t assume that the durability of snap lock systems is low – it’s just not that high, but still good.
Both technologies for joining standing seam metal roofing panels are popular, and the vast majority of contractors take on orders to install both snap lock and mechanical lock.
However, it must be openly admitted that residential roofing contractors are more likely to use snap lock panels, while companies engaged in commercial exterior services are far more likely to order mechanical lock systems. This is due to the differences lying between the specifics of corporate and private clients, differing expectations and also the economies of scale – in the case of small roofs, labor costs are not as noticeable as in the case of very large buildings, and it often turns out that snap lock technology increases the price of the panels.
When comparing snap lock and mechanical lock with each other, it is impossible not to mention a very important criterion – the cost of purchasing the material and installation.
When buying roofing panels, the price differences will not be significant – usually, snap lock will turn out to be a slightly cheaper solution, but in many cases, the discrepancies will be so small that they can be ignored. However, taking into account the approximately 20% more expensive installation service, it turns out that snap lock roofing is up to 30% cheaper than mechanical lock panels, which is important for really large projects.
Assuming that the price per sqft of mechanical lock standing seam panels is about $4.8, while snap lock panels cost about $4.5, while the installation service costs $2.3 and $2.0, respectively, the average homeowner will pay between $16,250 and $17,750 for their new 2,500 sqft standing seam roof. There are differences in the price of roofs on residential buildings by all means, but about $2,000 is a sum worth paying extra in exchange for the much longer service life that comes from using mechanical lock.
For residential roofing, by far the most common way to connect standing seam panels is snap lock. The requirement to achieve a slope of no less than 3:12, mildly lower reliability and undeniable aesthetics make homeowners eagerly opt for snap lock rather than other, potentially more optimized solutions.
An additional advantage of snap lock in residential applications is its relatively easy installation, which can be carried out by someone with a relatively low skill level and without complicated tools.
For commercial applications, the choice is not so easy and is dictated more by design details.For classic-style buildings with roofs consisting of many narrow panels, snap lock is proving to be a relatively good solution, mainly due to the lower risk of damage from thermal expansion of the metal. On the other hand, buildings with flat, very large roofs should be covered using specially designed mechanical lock panels.
Choosing between snap lock and mechanical lock metal roofing panels involves weighing factors such as installation speed, sealing capabilities, aesthetics, durability, and cost. Snap lock systems offer quicker installation and lower initial costs, making them suitable for residential projects in moderate climates with steeper roof pitches. Mechanical lock systems, though more labor-intensive and costly, provide superior performance on low-slope roofs and in regions with harsh weather conditions.
In our opinion, mechanical lock roofing panels are usually the better choice, but we know that you need a reliable roofing contractor to install them. However, if you find a trustworthy company, you will definitely be happy with your choice.
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Contact us
Do you need personalized offer?
Call or write to us – let’s talk about what we can do for you!
(847) 947-6797
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Northshore Sheet Metals
ABM Distributing, Inc.
418 Mercantile Ct.
Wheeling, IL 60090
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Sunday: Closed
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