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TOPIC: Exposed Fasteners

Metal Roof Fastening

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Is it really a significant improvement to attach a stone coated metal roof with screws vs nails?
Guest User

7/3/2002
I represent a company that makes one of the products you descibe although we prefer to call it a granular coated metal roof. There are two considerations inthe fasteners in this type of situation. First the climate. As these types of sytems are typically fastened to battens, when wood is used some copanies allow nails. In climates that move from hot and humid in the summer to cold and dry in the winter, the wood will expand and contract with the moisture and can loosen a nail where a screw will hold tight. I haqve seen it then where the ice will grab a hold on the loose nail and pull it right out. The seconnd consideration is the type of material the fastener is made of. A long life nail of the correct size would be better in most cases than a undersize screw made of poor material. My favourite expression to use in this situation is" Do you think that when they produce a Cadillac, that they nail it together or screw it together?" Roof systems go through a lot of movement on a building and a screw is the best protection to keep the roof system in place. In the southern dry desert climates a properly sized and located nail will do an adequate job. Hope this helps.
Allan Reid
Dura-Loc Roofing Systems, Inc.

7/8/2002
Can someone point me to a spec for moutning hardware (i.e., type of screws and length) for mounting corrugated metal panels to 1/2" plywood roof? I assume the scre should be approved WOOD screws, but am unclear on the Min. length they must penetrate the plywood -- all the way through, part way, etc.
Guest User

7/21/2002
Can someone point me to a spec for moutning hardware (i.e., type of screws and length) for mounting corrugated metal panels to 1/2" plywood roof? I assume the screw should be approved WOOD screws, but am unclear on the Min. length they must penetrate the plywood -- all the way through, part way, etc.
Guest User

7/21/2002
You should adhere to the panel manufacturers' installation guidelines in choosing fasteners. Generally, though, you'll be using painted galvanized steel screws with cap-style heads and neoprene washers. In most cases, the suggested length is 1". In your case, this would penetrate the plywood. When going into thicker lumber, though, 1" is generally what is suggested. The screw size will vary between #9 and #15 typically with heavier shank screws being used in more demanding situations -- roofs with long rafter lengths and areas prone to strong thermal changes. Todd Miller
Todd Miller
Isaiah Industries, Inc.

7/22/2002
I LIVE IN CENTRAL WEST VIRGINIA, WE HAVE TEMPERATURES FROM "0" TO "90" PLUS EACH YEAR. I AM INSTALLING A SHEET METAL ROOF ON A BRICK (REAL BRICK) BUILDING THAT IS AT LEAST 80 YEARS OLD. IT HAD ROLL ROOFING WHEN I BOUGHT IT. IT leaked!! . THE attic SPACE VARIES FROM 1' ON THE LOW END TO ABOUT 4' AT THE HIGH END. THE ROOF IS 40' FEET LONG AND 38' WIDE. THE SHEETING IS SOLID LUMBER 1' THICK. THREE QUESTIONS: 1. SHOULD I USE AN UNDERLAY? 2. WHAT TYPE OF FASTNERS? (I PREFER SCREWS) 3. DO I HAVE ENOUGH SLOPE TO use METAL ROOFING? THANK YOU.
Guest User

5/10/2003
Hi Bob, Ultimately, all of these questions must be answered in particular reference to the metal roofing product which you choose. However, in general, 1) Yes, a moistur ebarrier underlayment is important beneath the metal roofing. From tiem to time, condensation can occur on the back of the metal and you do not want that to reach the decking or anything else beneath the roofing. 2) Virtually all metal roofs can be installed with screws. Some, as an option, can also be nailed. Make sure that the metal of your fastener is compatible with the metal of the roofing. 3) Your roof pitch appears to be somewhere slightly steeper than a 1:12 pitch. Again, this needs to be reviewed in regards to the roof you choose. However, for the most part, this will limit you to a field-seamed standing seam, meaning that a crimper will have to be run down the interlock of the panels after they are installed. Todd Miller
Todd Miller
Isaiah Industries, Inc.

5/10/2003