QOD 3/4/2006 Roofing

The education committee has made a schedule for the QOD. A different member will post questions for a one week time frame. We did this so that you could have a wide variety of questions.

March Schedule
3-4 thru 3-10 Greg Bell
3-11 thru 3-17 Dave Bush
3-18 thru 3-24 Aimee Jalowsky
3-25 thru 3-31 Claude Lawrenson

How can you report hail damage if there is no hail damage. You can have hail and then you can have hail. All hail does not cause damage, and all hail damage is not always of concern?

Any metal roofs I see are never nailed they are screwed with washer.

Hi Ray,

Claude will be doing the questions at the end of the month. I hope that you find his more useful.

Have a great day.

The correct answer is D.


Not to be difficult, but D is not the correct answer. Metal roofs are not nailed, they are most always screwed.

So the question and the answers do not jive.

Screws or nails an inspector is still looking for the same problems.

If the inspector did see nails then should he not report that it is improper?

Yes if it is nailed it is a problem. But the question is " C. improper nailing."

Screws are not improper, nailing is. That is not what the question asks or states. It implies that nailing is okay, the way I read it. :slight_smile:

Since you called me out I had to go find a manufacturer that allows nails.


FABRAL can supply either screws or nails for fastening into dimension lumber, with screws offering better pullout values. Woodgrip screws for use with steel panels are galvanized and then coated with an organic polymer for optimum corrosion resistance. For best results with aluminum panels, use #300 series stainless steel Woodgrip screws.
The FabrOseal® galvanized ring-shank nail, with its premium long-life silicone rubber gasket, assures a lasting seal and is the best nail available for steel panels when screws are not desired.
The correct way to fasten steel panels with nails is to drive the nail through the top of the rib so the washer is compressed securely against the metal. Nail placement must be in the ribs for roofing applications to minimize the potential for roof leaks. Over-driving the nail can split the washer and dimple the metal, causing leaks.
Wood screws with combination metal and neoprene washers should be installed in the flat area of the panel adjacent to the ribs, and tightened such that the washer is compressed as illustrated above. This will ensure a lasting, leak-proof seal. See pages 4 to 5 for the correct fastener locations.

So why would they make a nail to use with steel panels when you say that they are not allowed?

I will agree that if I were having a metal roof installed that I would choose screws over nails 100% of the time. But to say that nails have never been used is untrue.

Thanks for that, that is news to me. But as you and they say screws are much better. They resist pullour forces much better. I have yet to see a metal roof that used nails. For instance my barn has a metal roof and it is secured with screw/washer.

So now I have learned something!

So, in the end, we’ll chalk this-up to semantics. The question (answer choice) should simply have said “improper fastening.”

Hey Chris,

While that may be true we would not have had such a great learning experience if it hadn’t been worded the way it is.

Interesting issue with the nails. I designed, marketed, sold and supervised metal roofing installations for more than six years. Including the World’s Largest single project at Walt Disney World. (Caribbean Beach Resort 1.5 million square feet)

I wonder how roof panels test for wind when nailed vs. screwed on. I’d almost bet that they don’t meet the Florida Wind Codes when nailed. Our Company never used nails, always used self tapping metal or wood screws based on the substrate we were installing the roof on.

The older the metal roof, the more likely the exposed screws will serve as possible areas of water penetration. The expansion and contraction of the roof panel will elongate the original screw hole. What was once a round hole has become an oblong hole. Usually a large diameter screw with a larger neoprene washer solves the problem.

While going through my old ASHI Training Manual I found some info related to this. It speaks of nailing down the panels used for metal roofing.

2.5.1 Metal Roof Coverings
Corrugated roofing should be fastened to the framing through the high point of the corrugation with a special nail that has an elastomeric gasket under its head.