Are you considering installing a metal roof and concerned about the dangers of lightning? Your concern is understandable, but the short answer is that metal roofs do not attract lightning. Other factors are much more important in where lightning strikes. Read through the sections below to further understand the dangers from lightning.
What is Lightning?
A “flow of electrical current between earth and sky” is the description of lightning given by The Metal Construction Association. The flash that we see is a path of electrons pushing from the sky to the ground, showing a line of ionization. Lightning reflects the buildup of static electricity in clouds, commonly during a thunderstorm. We can observe ‘intra cloud’, ‘cloud-to-cloud’, and ‘cloud-to-ground’ lightning. Cloud-to-ground is the lightning we are concerned with, as it is the only kind that strikes our buildings.
What Affects Where Lightning Will Strike?
Cloud-to-ground lightning looks for the quickest path to the earth from the part of the cloud that has the highest concentration of static electricity. It typically finds tall trees or the largest, highest structure in the vicinity. If your building is built on the top of a hill, this will make it conducive to lightning strikes. If this is the case, you may want to consult with a local lightning expert.
Though metal is an excellent conductor of electricity, this does not mean that lightning will prefer it as a path to the earth. However, it is important that your building be grounded since the lightning is ultimately seeking the ground.
What Happens if Lightning Strikes my Metal Roof?
If lightning should strike your metal roof, it will immediately spread the electrical charge through your entire roof, and also find your ground connection to the earth. Since metal is a non-combustible material, the heat from the electrical discharge will not set your roof on fire. It could do that if you had roofing material composed of wood or asphalt. So metal roofing is actually a safer roof than most others.
Beyond the protection afforded by the metal roof, if your underlying structure happens to be of metal, this will be another advantage. The metal will spread the effect of the strike and will not start a fire. There would be a chance of fire if the roofing structure were made of wood, as with many buildings. In fact, the Metal Construction Association says that since metal is both a good conductor of electricity and is non-combustible, it is probably the best choice for a roof. Keep in mind that your metal roof can protect you in event of an electrical storm.
Your metal roof gives you personal protection, but electrical equipment in your building needs additional protection. That is why in a storm with lightning we unplug electrical devices such as our computers, phones, sound systems, and TV’s. If you live in an area with many powerful thunderstorms, consult an authority in your area for a lightning system which can protect all your assets. This system will provide for your assets a constant grounding system between the earth and the sky.