#3 – Fire Safety of Metal Roofing
February 20, 2017 | Filed under: Metal Roofing 101 Series, Roofing Help Videos
As homeowners, we take a lot of steps to fireproof the interior of our homes. But, when it comes to the exterior of our homes, the risk is out of our control. It can come from nearby wild fires, lightning strikes, or unfortunate fires at our neighbor’s homes. Metal roofs are non combustible and can offer some of the best available protection from external fires. And, unlike some other roofing materials, they offer this protection without any special fire resistive treatments which tend to wash away after a few years of exposure to the weather.
Additionally, in the event of an interior fire, the low weight of metal is of great significance. Heavier roofing materials increase the chance of a roof caving in once the fire reaches the attic. In fact, with some heavy roofing materials such as clay and concrete tile, fire fighters will not even go inside to fight the fire due to the risk. A combustion resistant metal roof can bring great protection to your home and great peace of mind to you.
Todd Miller has spent his entire career in the metal building products manufacturing industry. He is president of Isaiah Industries, an organization recognized as one of the world’s leading metal roofing manufacturers. Todd is currently Vice President of the MRA (Metal Roofing Association) and a Past Chair of MCA (Metal Construction Association). Through his website, he strives to raise the bar on standards and practices to provide property owners with the best possible products for successful roofing projects.
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Can you comment on the relative comparative advantages and disadvantages between aluminum, standard steel, stainless steel, and other more exotic metals for roofs relative to specifically fire. Someone I spoke with seemed to think steel was superior to steel in a fire because the aluminum will melt while the steel is still strong and resistant to the flames.
Thank you. This is a good question. The melting point of steel is considerably higher than that of aluminum — about 2500 degrees compared to about 1250 degrees. This means that both will resist small blowing brands until they self extinguish. And hotter fires would be attacking other areas of the home as well. However, through the use of fire resistant underlayment, aluminum roofs can pass the same fire tests as steel roofs. Additionally, in the event of an interior fire, having the fire be able to burn up and through the roof at a lower temperature can be beneficial rather than have the fire spread through the attic. Of course, again, if the fire resistant underlayment is in place, aluminum and steel will be essentially the same in that regard. I
Your comment was cut off after this phrase, “…essentially the same in that regard. I…”, could you post the rest? Can you also describe the fire resistant underlayment and give some specific products so I can research this. Do you happen to know which roofs (aluminum or steel) firefighters prefer? Finally, I have heard recently about light-weight roofing tiles Can you share about them and how they compare with metal roofs, especially aluminum?
Hmmm. That is odd. Not sure what happened to the rest of my response, nor what I was going to say. Firefighters are typically trained how to “open up” metal roofs if they need to vent the attic. That said, ultimately, aluminum roofs and roofs with lots of interlocks rather than mechanical seams are probably easiest to open up. A commonly used fire resistant underlayment is Versashield by GAF. There is also a product called Dens Deck that can be used, as well as some others. I am not sure what sort of light weight tiles you have heard about but if they are cement based, they are still heavier than asphalt shingles. Aluminum roofing weighs about 0.45 – 0.7 pounds per square foot. Steel weighs about 0.8 – 1 pound. Asphalt shingles weigh from 2.75 – 4.25. I hope this helps. Feel free, if you have more questions and it’s easier, to just email me at firstname.lastname@example.org
IS IT HARDER TO REMOVE A METAL ROOF DURING A FIRE THAN A SHINGLE ROOF
A part of fire fighting training is how to cut through various roofing materials. Most metal roofs are fairly easy to open up in this event. Of course, lighter gauge products as well as aluminum products and also products with a lot of interlocks or overlaps are easiest.
A fire manager at Oregon department of forestry told me that, should I have a fire in my gutter, the flames could ignite the 15# felt underpayment under my “high rib” steel roofing, spreading fire to the roof sheathing.
True? This seems very counterintuitive. For one thing, I haven’t noticed 15# felt being particularly inflammable, much less when it’s only exposed to air at tiny openings at the bottom of high rib roofing. (Problem for me is I can’t clean one section of second floor gutters, due to solar panels blocking access. Fortunately, my second floor gutters don’t collect a lot of leaves.
Thanks for being here, and for y9ur assistance and knowledge!
15 pound felt may be fire resistant but certainly not fireproof. If there are leaves in the gutter and they catch on fire, there is always a risk of that fire reaching wood and igniting. Chances are, though, unless the leaves are piled way up on the house, I would expect them to burn out before they have a chance to spread.