The Pros & Cons of Commercial Metal Roofs

Over the last decade, metal roofs have become all the rage for both residential and commercial buildings. Touted for their durability and aesthetics, many building owners are considering these sleek, modern systems.

But the question is: is a metal roof a good investment for your building? 

The answer is: it depends. Metal roofs have some definite advantages over the more popular and established single-ply roofs like TPO and PVC, but there are drawbacks, and your choice depends on several factors. 

Fortunately, at GIDEON, we've installed and repaired every kind of commercial roof system over the last two decades, and we're intimately familiar with the advantages and disadvantages of each. In this article, we'll discuss the pros and cons of commercial metal roofs so you can determine if they're the right choice for you.

Table of Contents

• Pros of Metal Commercial Roofs
• Metal Roofs Are Very Durable
• Metal Roofs Are Low Maintenance and Long-Lasting
• Metal Roofs are Environmentally Friendly
• A Metal Roof Improves Your Asset Value
• Cons of Metal Commercial Roofs
• Metal Roofs Are Expensive
• Quality Installers Are Hard to Find
• It may Be Harder to File a Claim for Hail Damage
• Excessive Expansion & Contraction
• Lower Thermal Performance

Pros of Metal Commercial Roofs

Metal Roofs Are Very Durable

The most commonly mentioned upside of metal roofs is durability. Typically made of steel or aluminum, these systems are highly fire-resistant, making them an excellent choice for areas prone to wildfires. By contrast, the most popular single-ply system, TPO, is much more vulnerable to fire risk. Metal systems can also resist gale-force winds that would tear a single-ply membrane. They can also handle heavy foot traffic, making them an attractive choice for industrial applications. 

Metal Roofs Are Low Maintenance and Long-Lasting

Metal roofs can last 40-70 years, substantially longer than the 15-25 years most low-slope roofs get. 

They also require less maintenance simply because steel and aluminum are tougher than single-ply membranes. Metal roofs also tend to have a steeper slope than other commercial roofs, so ponding water (where water forms a small pool on the roof) is less common. In fact, if installed correctly, metal roofs often won't experience any significant maintenance issues until 20-25 years after installation - quite a bit longer than the 10-15 years seen on other flat roofs.

And when maintenance is required, it is simpler and easier than your average single-ply. Damage is easier to discover visually, and less prep work is necessary to mend it. 

Of course, this doesn't mean you can simply "set it and forget it." Bi-annual roof inspections are still essential to due diligence and are absolutely recommended for metal roofs.

Metal Roofs are Environmentally Friendly

Environmental friendliness is another much-touted benefit of metal roofing. Unlike other roofing materials, which often end up in a landfill at the end of their useful life, metal can be recycled and repurposed. However, even this is only sometimes necessary because, even after their useful life, metal roofs can be considered a decking substrate and either coated with an elastomeric coating or covered with a new metal or single-ply roof.

A Metal Roof Improves Your Asset Value

The advantages mentioned above make metal roofs very desirable to potential buyers. Whether you're a buyer or a seller, commercial metal roofs' longevity and low maintenance requirements can provide substantial savings. For example, if you're selling a building with a 15-year-old single-ply roof, you'll likely have to replace it in 5 years (if it's been very well maintained). A 15-year-old metal roof, on the other hand, likely has another 20 years of life.

Cons of Metal Commercial Roofs

Metal Roofs Are Expensive

But metal roofs do come with disadvantages. The first is the price. Because metal roof installation requires more skill, costs for both labor and material are generally higher. But metal's longevity and low maintenance requirements can compensate for this higher upfront cost in the long run.

Quality Installers Are Hard to Find

Because of the skill and special equipment required, high-quality metal roofing contractors are in short supply. This leads some building owners to hire poor-quality installers whose ineptitude negates many of metal roofing's natural performance advantages. At Gideon, we've had to replace 10-year-old metal roofs because they were so poorly installed. They were simply unsalvageable.

It may Be Harder to File a Claim for Hail Damage

Metal roofs tend to be easily dented by hail. In fact, it happens so often that many insurance carriers now have exclusions for "cosmetic hail damage." Essentially, they'll argue that while the hail has damaged the look of the metal, it has not damaged its functionality or reduced its useful life. While this is often true for steep-slope metal roofs, as they shed water more efficiently, it's not necessarily true for low-slope commercial roofs. Water sits on low-slope roofs for longer periods, damaging the clear coat, after which it can start to rust the metal itself. If you decide on a metal roof, it's important to discuss your insurance policy if you live in an area that's prone to hail.

Excessive Expansion & Contraction

Metal, of course, is highly sensitive to temperature changes. While metal roofs are designed to handle expansion and contraction, this phenomenon can cause serious problems if proper installation procedures are not followed. In the summer, daytime warming followed by nighttime cooling can cause the metal to expand and contract so much that seams will pop loose and screws will get ratcheted out of the panels. This creates avenues for water penetration.

Lower Thermal Performance

Metal roofs do not insulate the building as well as other roof systems. However, this is not because of the metal itself (which is coated with a reflective material that improves energy efficiency) but because of how the standard fiberglass insulation is installed. 
In these cases, fiberglass insulation is laid over the roof purlins, which are beams that go horizontally along the length of the roof (similar to a joist). There is no decking. The metal panels are then laid on top of the insulation. This means that parts of the insulation are tightly compressed between the metal roof panels and the top of the purlins, which reduces the effectiveness (r-value) of the insulation at the compression point.

The Upshot

If you're looking for a low-maintenance commercial roof that will go the distance, metal can be an excellent choice. But if you don't hire quality installers, you could end up with a six-figure heap of scrap metal, so it's critical to consult with a qualified professional. If you'd like to discuss your commercial roofing options, hop on a call with GIDEON. In a free, 15-30 minute call, our nationally-recognized roofing advisors can assess your situation and provide customized recommendations for your commercial roof.