What Are The Two Biggest Concerns About A Metal Roof (and How To Avoid Them)?

While there are numerous aspects that can impact the problems that might occur with a metal roofing system, things can happen that are beyond our control on occasion. Although it may not be the answer you want, metal roofing has fewer long-term concerns than other materials such as asphalt metal roofs over shingles or concrete tiles. There are two big concerns with metal roofing and those are corrosion and leaks. Below we will describe the different problems and prevention techniques to avoid them entirely.

Concern #1: Corrosion 

Many people prefer metal roofing because it resists corrosion and degradation for decades (often up to 60 years), making it the only roof they will ever need to purchase. Manufacturers and contractors can help you choose which metal material will best survive corrosion in the climate where your house or construction is located. Although there are few exceptions, most metal roofs feature corrosion-resistant paint systems or coatings. Here are a few corrosion examples that are commonly found on metal roofing.

Corrosion:

If the metal is not properly coated, it may appear on the underside of the panel. Water molecules become trapped between the panel and the insulation, causing the metal to corrode if not adequately protected. Furthermore, if a granulated underlayment is utilized or laid directly over a shingle roof, the protective backside coating may be scraped, resulting in the metal roof system collapsing from within.

Saltwater Corrosion:

Homes and structures near the seaside are typically unsuitable for warranties due to the effect of seawater on metal. Although aluminum and zinc work well in coastal locations, there is no guarantee that they will last as long as a roof is not exposed to seawater. When purchasing, read and assess the warranty or product specs thoroughly to see if you are in an area prone to early corrosion.

Dissimilar metals:

When certain metals are mixed, a negative reaction can occur, resulting in premature corrosion that would not have occurred otherwise.

Cut Edges:

Cut edges on a steel roof will experience edge creep, which is corrosion at the cut edge. Many standing seam metal roof features incorporate folds or hemmed edges to conceal the metal’s cut edge. Many roofing treatments, such as painting visible cut edges using a paint pen, can help to reduce edge creep.

Concern #2: Leaking

The last thing anyone wants is a leaking roof. In most cases, a leak can ruin other valuable items in your home or property, in addition to increasing the expense of replacing the roof. Metal roof leaks can occur for a variety of causes, some of which are beyond our control and others that are the result of human error. Leaks may damage the structure of your building as well as the different assets contained within, substantially increasing the cost of restoration if left ignored for too long. Extreme weather, such as ice that quickly freezes and thaws, is the most prevalent cause of leaks in metal roofs. However, there are other causes of leaking metal roofing.

Roof Slope:

A leaking metal roof can often be attributable to an inadequate roof slope. Most metal shingle roofs require four inches of rise for every foot of roof run, which amounts to a slope of 4/12. If the slope is smaller than 3/12, you have likely located the leak’s source. There are, however, a number of commercial roofing systems that may be placed on slopes of 2/12 or more if they feature a standing seam. There are exceptions for various types of systems, but if the slope is wrong, it is a safe bet that a lack of slope is the cause of the leaking roof.

Missing or poorly secured panels:

When metal roofing materials are not correctly placed, they might move or be blown away in high winds. This will only occur if the roof sheets were not properly fastened using fasteners. You may have to replace any missing materials if the metal panels were not interlocked or attached to the deck. Most metal roofs can resist winds of up to 110 miles per hour, thus blown-off panels are a solid indicator that they were constructed improperly, resulting in the leak.

Improper flashing:

If no flashing was built around susceptible portions of the home, such as around a skylight or brick chimney, leaks may occur. End walls, side walls, and roof valleys should all be checked. These are the regions where leaks usually start, so look into them, especially if you can not locate another obvious source of a leak.

Preventing corrosion

Metal roofing panels are produced and coated with modern paint techniques and finishes, and tested to avoid corrosion for as long as feasible. One method to avoid corrosion is by speaking with a roofing professional and discussing the most suitable material for your area. Here are some of the most popular rust-resistant coatings and steel types:

Galvalume Steel:

Galvalume is a coating used over the top of steel that is composed of aluminum, zinc, and silicone for corrosion and rusting resistance. If you live in a high-temperature, high-precipitation, or marine environment, this is an ideal coating to help your roof resist corrosion. Galvalume provides a more matte-looking final appearance.

Galvanized Steel:

A carbon steel coated with a zinc oxide protective alloy. The zinc coating protects and preserves the panels for decades. The galvanized steel is then coated with a resin coating, which provides a smooth, lustrous appearance and helps it resist scuffing and scratches.

Weathered Steel:

An extremely sturdy alternative for steel roofing that is designed to rust up to a particular extent. The finish is made using a coat of copper, phosphorus, and silicon that rusts when exposed to the outdoors. When the top coating is removed, the steel ionizes. This prevents the steel from rusting further and eliminates the risk of the panel being corroded all the way through. This is a rust-colored finish that is intended to rust for aesthetic purposes and lasts as long as other finishes.

Preventing Leaks

Any homeowner would want to protect their property from any water damage. One method of prevention from leaks for a metal roof is by applying a roof coating or sealant to ensure there are no crevices that water can seep through. Metal roof sealant is a substance that acts as a barrier against moisture, air, and airborne particles, as well as aiding in the prevention and repair of leaks. It is a secondary line of defense against leaks and should not be a roof’s only line of defense against water infiltration. Sealants come in a wide range of grades and compositions and can be created from acrylic, polyurethane, butyl (rubber), and silicone.  A silicone sealant is preferred for a metal roof system because it adheres well to metal and other common construction materials. It also provides great moisture and UV protection, as well as outstanding joint mobility.

Whether you install your metal roof yourself or hire a contractor, making sure the panels are fitted correctly is critical to preventing rust and leakage. Here are some things to keep in mind during installation. Edges should be sharp and properly cut. Any scratches should be repaired using a paint pen or another sort of sealer. Fasteners should be driven in accurately since overdriving, underdriving, and driving them in at the improper angle will cause corrosion on your panels. Ensure the roof’s seams are built and installed properly. After your metal roof is installed, it should be inspected thoroughly at least once a year. Keep an eye out for any exposed edges, severe cuts or scratches, or other problems that might expose the panels and cause corrosion. Also, be aware of any leaks that might appear after it has rained or snow has melted. If you have any concerns it is always best to speak to a professional metal roofer.