Metal Roof

Originally Posted By: kmcmahon
This post was automatically imported from our archived forum.



Does a metal roof need to be grounded? Client called to ask me that tonite before her inspection in the AM and I didn’t have an answer. To be honest, I’ve inspected several and never gave it a thought!



Wisconsin Home Inspection, ABC Home Inspection LLC


Search the directory for a Wisconsin Home Inspector

Originally Posted By: ekartal
This post was automatically imported from our archived forum.



Kevin.


I’m 9999999% sure that metal roof grounding is not required.


Erol Kartal


Originally Posted By: lewens
This post was automatically imported from our archived forum.



Kevin


In the lovely province of Quebec the rage for a while was, believe it or not, ORANGE metal roofs. I put on lots of them and the manufactures spec’s said nothing about grounding. Good point though, makes you wonder. Maybe we need Joe Tadesco or Jeff to jump in here.


Larry



Just my usual 12.5 cents


From The Great White North Eh?
NACHI-CAN
www.aciss-brant.com
www.certifiedadulttrainingservices.com/

Originally Posted By: dedwards
This post was automatically imported from our archived forum.



Would appear to me that grounding the roof would have the opposite effect of what you want, making it a lightning rod. Until you ground it or tie it in with the ground system it isn’t likely to attract lightning. Also if it is tied into ground would it not then become more dangerous if there is a bleed or short to ground? Good question, now I’ve got to go do some digging on the subject.


Originally Posted By: kmcmahon
This post was automatically imported from our archived forum.



Even more of a conundrum…turns out the shell and roof are metal. I’m still trying to come up with an answer one way or another…it seems, like myself, that no one has really given it a thought before.



Wisconsin Home Inspection, ABC Home Inspection LLC


Search the directory for a Wisconsin Home Inspector

Originally Posted By: tvalosin
This post was automatically imported from our archived forum.



I am checking with a local metal roofing specialist contractor friend (that is the only type of roof he does, or has done, for 25 years) However, proper grounding of an object DOES NOT make it more likely to “get hit”.


To simplify: In real life, a lightning hit occurs when the electrical potential of an object builds to the level that it must discharge. During an electromagnetic storm, opposite charges build on earthbound surfaces and stormclouds. When sufficient charge is built, nature attempts to complete the circuit, resulting first in a “leader stroke”, from the object to the cloud, then the full strength return stroke, cloud to ground. The whole idea of grounding an object is to provide a “bleed off” path to ground in order to keep the charge potential below the point a leader stroke can develop. No leader stroke, no full potential strike. (Okay you meteorologists, this IS meant to be a simplified explanation.) IMHO, I would ground my own place. For those interested, I also have a background as a Broadcast Engineer (SBE Life Certification) as well as Amateur Radio (Extra Class License). I got tired of being on call 24/7, so I learned to be a home inspector. I have installed many towers and worked within broadcast transmitter sites. (Metal building, grounded, under a 770 foot tower, for example.) Having been in the building during lightning storms, I opt for grounding. It seems the properly grounded broadcast situation actually MINIMIZES the chance of a lightning strike.


Originally Posted By: dedwards
This post was automatically imported from our archived forum.



Thomas,


Thank you for clearing that up. Very good explanation. My old man was into HAM radio back when I was a kid but he never let any of us within a thousand yards of any of his equipment and never explained any of it to us either.


Originally Posted By: tvalosin
This post was automatically imported from our archived forum.



I just got off the phone with the Metal Roofing Specialist I referred to in my last post. Here is a summation of the info provided.


In the metal roofing trade, their national organizations have, over the years, commissioned several independent research projects and experiments regarding the topic of grounding. It was found that metal roof structures are “no more likely to be struck by lightning than non-metal roof structures” At this time, the trade organizations do not take a position for or against grounding. Grounding or not grounding is up to the individual contractor and client. There has been some effort by some code, insurance companies and safety people to force grounding but, based on the research and and historical information, the metal roofing industry has been able to send these efforts to ground (pun intended). In addition, based on the research and historic data, the industry has taken the stand that if it is required to ground metal roofs, all roofs should be grounded.


Originally Posted By: kmcmahon
This post was automatically imported from our archived forum.



Tom,


Excellent. That’s the kind of information I was looking for.



Thank you.

Kevin


--
Wisconsin Home Inspection, ABC Home Inspection LLC

Search the directory for a Wisconsin Home Inspector