bonding metal building siding

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hbeery10

hbeery10

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Sardis, Ohio
We have ran into this situation a couple of times and was wondering what others think. When you have a wood framed structure covered in metal siding, does the siding need to be bonded? If necessary, would I size the bonding jumper by 250.66? Typiclly the siding is 3' wide ribbed sheets. One of my issues is that typically the panels are not fastened through the ribs, but on the flat with screws that have rubber washers. A single rib overlaps, but there is not a screw that penetrates through BOTH panels at any given point. Seems to me that if it is required to bond the steel every piece either needs to be connected to each other or each piece needs to be individually bonded. I'm not sure if the reason for wanting to bond it is for ground fault situations or static discharge or something else?? Maybe somebody else has experience here. Thanks!

Thanks,
Garth
 
I do not think it requires any kind of bonding or grounding in general.

if it is near a pool, it probably needs to be bonded to the pool bonding system.

it might need to be bonded if it is close to a down conductor for a lightning protection system.

I do not see any simple means by which this kind of thing can be bonded. They are usually painted so you would have to scrap the paint off and lug to each section. I do not believe they are thick enough that a screw of any kind would be an adequate connection.
 
Had inspectors require it then tell me that it was not in the NEC but was in the states basic building code. Don't have that book to see if it's really there. Then had one inspector tell me that he didn't agree with it either as he had seen an incident where a lightning strike burn holes around every one of those sheet metal screws.
 
One of the first lightning jobs I was on as a young man was where the chimney took the brunt of the hit on a 2 story house with a steep roof up on the top of a hill. It took the top 8-10' off the chimney - blew it to the ground. Other damage was the rain gutters were on the ground directly beneath where they had been installed - It blew the spikes out of the ferrels. And the last of the damage was sheetrock screws popped in the area of the master bedroom closest to the chimney on the 2nd floor.

Are you going to bond the gutters?
Are you going to bond every sheetrock screw?
How about 16d framing nails? 8d sheething fastners?

A building with conductive siding does not in and of itself constitute a metal building. Same for roof panels.

An inspector who requires you to bond the metal siding on a wood framed building is wrong.
 
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