The benefits of metal roofs and coatings

Valspar_CA_BeckwithAnimal Hospital1
Photos courtesy Kingspan Insulated Panels/Valspar

by Jeff Alexander
Recognized as sustainable, durable building components, metal roofs are used in various applications. The performance of the assembly’s panels depends on the metal substrate, metallic layer, and exterior coating. These are critical to the panel’s weather and corrosion resistance, color retention, and overall longevity.

Finished with the proper coating system, ‘cool’ metal roofs can also help reduce a building’s carbon footprint, energy consumption, and cooling/heating loads. In addition to directly benefiting the building owners and occupants, these roofs also assist in benefiting the surrounding community by mitigating the urban heat island effect.

Metal roofing substrates
Metal roofs can last longer than most non-metal roofing products. Their materials contain recycled content and are 100 percent recyclable at the end of their useful life. Metal roofs can be designed to withstand extreme weather conditions and are more fire-resistant than other roofing materials such as wood or asphalt. A metal roof can be one-eighth the weight of other roofing products, placing a lighter load on the structure and foundation and extending the life of the entire building. The lightweight system also makes them easier to transport and install, further saving on time, as well as financial and environmental costs.

Steel and aluminum are both used in the manufacture of metal roofs, with the former being the most common. In weight, pound for pound, steel is economical metal roofing. Steel’s strength and durability throughout its service life, as well as its lifecycle cost, make it an attractive investment. Steel and aluminum are amongst the most recycled materials in the world with more than 50 percent of steel supply in the United States and 40 percent of the aluminum supply in North America being produced through recycled sources.

Valspar_CA_BeckwithAnimal Hospital3
Located in Modesto, California, Beckwith Veterinary Hospital’s 1300-m2 (14,000-sf) facility used green building strategies to save resources and promote sustainability. Design features include photovoltaic (PV) power and insulated standing-seam metal roof panels with a copper finish.

Corrosion can affect the structural integrity and durability of roof metals and alloys. Localized corrosion can lead to pitting, cracking, and eventual fractures, causing leakage or more serious failure of building components. The metal roofing substrate can be protected from corrosion with one of two types of protective metallic coatings: sacrificial and/or barrier protection.

Sacrificial protection involves having a protective metallic coating that gets attacked by corrosion, instead of the steel. Eventually, this sacrificial coating will be completely corroded away, leaving the bare steel to rust. Barrier protection is intended to repel the corrosive media. There is little attack by the corrosive media on the barrier-type coating.

Galvanized coatings are metallic coatings most popularly used to protect metal roofs from corrosive media. This type of coating is a zinc-based metal covering that comes in either G60 or G90 of zinc of the total area covered and is a sacrificial coating.

Coatings containing a five percent aluminum-zinc alloy also serve as a sacrificial coating. Another type of coating is an aluminum-zinc alloy composed of 55 percent aluminum to 
45 percent zinc; it is produced in either AZ50 or AZ55 coating weights. This 55/45 percent aluminum-zinc alloy coating functions both 
as a sacrificial and a barrier coating, with its zinc providing protection on exposed edges or scratches and its aluminum providing a barrier to corrosive media.

Exterior coatings
Exterior coatings further enhance a metal roof’s aesthetic and performance characteristics. To ensure uniform gloss, color, and thickness, a coil-coat process is the preferred application method for metal roofing. Using this method, the rolls of metal are painted prior to them being shaped into the roof panels. These pre-painted sheets of steel or aluminum can be cut, slit-formed, corrugated, profiled, and molded into shingles, shakes, curves, and various shapes for distinctive architectural designs.

Exterior coatings for metal roofs are composed of four main elements: resin, pigment, solvents, and additives. The pigment particles are suspended within the resin, and the mixture is then reduced to a liquid form, providing an easy application to a metal surface.

The resins primary function in a paint formulation is to bind together all the components within the coating. It is the primary source for a coating’s durability and physical properties. Resin increases the physical strength and chemical resistance of the coating film, and allows the chemical reaction of the curing process.

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39 comments on “The benefits of metal roofs and coatings”

  1. Understanding how a roof is built is crucial to knowing how to work on it. There is more to a roof than just a bunch of boards nailed together with some type of covering on top of them. It takes a lot of skill to know how to roof and how to work on them.

  2. I can’t agree with you more Jason. There really is a lot of skill and knowledge that goes into roofing. Knowing how to do exterior coatings for example is crucial because if they are not done properly there could be leaks in the roof.

  3. Jeff, this was just the information I was looking for about coatings. My husband and I want to replace our roof with a metal one. We have heard good things about them. We are also trying to decide if we should get a coating. I will have to show this to my husband and see what he thinks.
    Emily Smith

  4. It’s interesting to see that roofs can be made out of metal. I suppose I have seen some roofs made of metal on barns. When I lived in the Philippines, it seemed like everyone’s roof was made of metal. It was really loud when it rained.

  5. My wife and I were planning to replace our roof here soon, and we were thinking about getting a metal roof. We have heard some good things about metal roofs, but we just weren’t sure if that was the best option for us. I really appreciate you telling me that these roofs last longer then other ones. I think that is going to be super important to me, because we plan on living here for a long time. Thanks a ton for this information! It was a huge help.

  6. One of the new trends I’ve noticed in my area is copper roofing. Whether or not it is used for the whole roof or just as an accent, I really like how it looks. My roof needs to be reshingled soon, but maybe I should upgrade to a metal material instead.

  7. Thanks for sharing this advice on getting metal roofing and coatings for your home. I had no idea that steel and aluminum are some of the most recycled materials in the world– that is really awesome! Just the fact that I could recycle 100% of my roof after it has gotten too old makes me feel like I am helping the environment a lot.

  8. This is some great information, and I appreciate your point that metal roofing lasts longer. My asphalt shingle roof is getting kind of old, and is in pretty bad shape. I want to have my roof replaced, and I was wondering if metal could be a longer lasting option. Is metal roofing available for residential property, as well as commercial? Thanks for the great post!

  9. I love the copper roof on in the pictures of the hospital. I’ve noticed several houses and business in my town using metal for their roofs. This trend is really attractive and practical too! Matching it to the stone, like the way this building has, makes it stand out even more.

  10. I have seen some roofs with metal on it, I didn’t know that some where made of recycled material. I think recycling is great, and it is cool to see all the different ways we have come up with to use those recycle materials. The fact that they last longer is nice too.

  11. Thanks for your information. I have heard a lot about metal roofs helping keep a house cool, but I never really understood it. However, I also didn’t think about the reflective ability of the roof. It is like difference sun shades have on the temperature of parked cars. When it is time to replace my roof I will have to consider getting a metal one.

  12. I need to replace the roof on my business, and I have been thinking about using metal material. That being said, you talk about how steel is the most common material used in the manufacture because it is the most economical metal roofing. I would definitely think that this would be the best option because, as you say, steel has such a high durability. So, the economical cost of this type of metal roofing is not just in the manufacture, but in the overall longevity of the roof. I will definitely look into this option for my own roof. Thank you for sharing!

  13. I think it’s really great that metal roofs can be a more energy efficient. I think it would be great to see these more in residential areas to cut down on heating and cooling bills. Do you know if solar panels can still be installed on metal roofs?

  14. I love the look of copper or any other metal material on a roof. I think it is much more attractive that shingles, so I am glad to hear that it also lasts longer. When we have our roof redone, I am planning on switching to metal. I’ll have to look into getting a coating to make it last longer.

  15. There is so many types of roofing materials these days. I really like the look of the metal roof. I also like that it is light in weight. And I am glad there are ways to prevent corrosion in the metal roofing. Any roof can be a big investment for it to have to be replaced a few years down the road. Glad there are ways to protect my investment!

  16. There are almost endless benefits for having a metal roof so this was really informative. The trick is to figure out exactly what would work best for your specific situation. Thanks for the advice!

  17. With metal roofs, they offer many benefits over traditional roofing materials. One of them is that they are very durable. How often do you see metal roofs flying off during a wind storm? Also, you are thinking green when you go metal since aluminium and steel are some of the widely recycled metals out there. Just be sure that for whatever metal you choose, that it gets installed by a professional.

  18. Metal roofing is the No1 solution when it comes to return on investment, resale value and low maintenance costs, not to mention it is the most stylish looking roof that you can install… With all that in mind it’s not hard to see why it is becoming the most popular roofing choice for new home owners.

  19. I think it’s cool that there is a special protective coating that’s purpose is to take the corrosion, instead of the metal. I also think it’s great that metal roofs are 100% recyclable. I’m all about recycling because there’s no need to make something new when there are already materials ready to be used. Thanks for the info!

  20. The benefits of metal roofing as mentioned in the article do sound interesting. Reading about it has me thinking of the aluminum sheet that my uncle fabricates at his shop. I’m having thoughts about maybe using the sheet as a roof to cover my shed.

  21. Thanks for sharing this info, Jeff! Considering the possible benefits that can come with a metal roof, I don’t see why more people are springing to have one. Being able to have my roof reduce my energy costs with special coating sounds like a deal to me.

  22. I’ve heard that a lot of people are using metal roofs lately, and I’ve been considering doing the same. However, I had no idea that an exterior coating was an option. Reading your section about the metal coating, it sounds like a really good option. Perhaps I could look into the latter option, thanks for this help!

  23. There seem to be some really good things about metal roofs. I didn’t know that the material could be one-eighth the weight of other roofing products. I feel like each of the advantages of using metal each has its own sets of benefits.

  24. I like your advice on how metal roofing is 100% recyclable at the end of its useful life. I would imagine that being able to recycle your roofing material once it is no longer useful would be really beneficial. My husband and I are looking to install a new roof for our home so maybe we should consider installing a metal roof.

  25. In your article, you stated that metal roofs can be designed to withstand extreme weather conditions and are more fire-resistant than other roofing materials such as wood or asphalt. My neighbor came over last night because he noticed that some or our shingles on our roof were damaged. Can a metal roof be installed on any type of roof or any kind of house? Hiring a roofing contractor might be our best option.

  26. I think metal roofing is a great decision. Like you said, they are made from recyclable materials, and can be recycled later! Plus, they are super energy efficient, which is a killer at my house. I would love to have a metal roof to help cut down some of my bills.

  27. I learned a lot about roof coatings by reading this article. It was cool to learn that roof coatings can help to reduce a building’s carbon foot print within the community. I hope this article can help us to know what is best for our roof if we ever need to work on it.

  28. It’s interesting that you pointed out that metal roofs last longer than most other roofing types. My roof is getting pretty old, and the shingles are starting to crack, so I want to have it replaced before I start having trouble with leaking. It would be nice to not have to worry about replacing it again for a long time, so maybe I could have metal roofing installed.

  29. Thanks for bringing to my attention that metal can be much lighter than other roofing materials. My wife and I need to replace our roof, and we’ve been talking about potential materials, but we thought metal roofing would be too heavy for our house to support. The durability of metal is enticing, so now that we know that it’s actually lighter, we’ll look more into that option.

  30. I thought it was really interesting how the article mentions that metal roofing can last much longer than other materials. I have also heard that they provide excellent insulation qualities as well. Despite a higher initial cost, these benefits seem to make a metal roof pay for itself in the long run!

  31. I appreciate that you went into detail of what metal coatings contain. I was unaware that exterior coatings contained elements that make the application very easy. Honestly, it’s surprising how we can use science to help develop things like coatings for metal. It’s exciting!

  32. I never knew that metal roofs last longer than non-metal roofs. I also like how you mention that metal roofs are 100% recyclable at the end of their life. I’m looking for a greener option for my roofing material, so maybe I should consider a steel roof.

  33. Thanks for explaining the benefits. My husband told me to call some roofers and install a metal roof for our house. I am now looking up some roofers to install it.

  34. The roof that we’ve been using was broken after the last hurricane, and now, my dad was planning to get it replaced with a possibly sturdier one. I was researching for options when I came across your article. I honestly thought it was great how you said that metal roofing is a lot sturdier than its non-metal counterparts. Aside from that, metal roofing is also 100% recyclable making it useful in more ways than one. Thanks for sharing this. I’ll make sure to let my parents know.

  35. I’m grateful for your advice about the benefits of metal roofing because they can last longer than most non-metal roofing products, and their materials contain recycled content and are 100 percent recyclable at the end of their useful life. Our roof is a bit worn out, and we’re considering on replacing it. Thanks for mentioning that metal roofing is can be designed to withstand extreme weather conditions and are more fire-resistant than other roofing materials. Thanks for the tips! http://www.earhartroofing.com/past-projects

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