Fastener Screw or Nail Spacing Tables for Exposed Fastener Metal Roof Panel Systems
METAL ROOF EXPOSED FASTENER SPACING - CONTENTS: Exposed fastener metal roof systems. Designs of panels used in exposed-fastener metal roofs. Set proper metal roof panel length to avoid buckling with exposed fastener systems. Proper metal roof exposed fastener type and location for exposed-fastener metal roof panels. Installation guide for agricultural building roofing or "metal barn roofing". Characteristics of metal roofing materials: exposed fasteners, barn roofing, other exposed fastener roof systems. Best practices for exposed fastener metal roofing material installation, flashing, ventilation, nailing, underlayment
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Spacing recommendations for exposed fastener metal roof systems:
This article describes the fastener screw or nail schedule for several types of exposed fastener metal roof systems, citing manufacturers' installation manuals and guidelines. We include a discussion of the requirement for use of a greater number of metal roof fasteners in high wind zones and we give an example schedule of the number of screws recommended for metal roofs at various wind speeds or wind zones.
This article series explains the selection, applicability, and installation specifications for exposed fastener metal roof systems, also referred to as barn roofing, or agricultural building roof systems. Because this roofing material is also sometimes used on residential buildings, homeowners and home inspectors should also review this material when diagnosing roof problems. Our page top photo illustrates the fasteners on an exposed fastener metal roof installed in Hamner Springs, New Zealand.
Exposed Fastener Metal Roofing Fastener Spacing Schedules & Tables vs Wind Load
At above left: a diagonal patterned, minimally-fastened exposed metal fastener roof panel system in the field of the roof on a building in Akaroa, New Zealand. But notice the closer fastener spacing on the roof's hips.
[Click to enlarge any image]
Where purlins are used in roof structure construction in this area, for wind damage protection a fastener may be installed on every other raised rib along the roof's eaves.
Below : two photographs of an older exposed metal fastener roof on St. Cuthbert's church in the Port Hills area above Christchurch, New Zealand, you can see fasteners in every other rib of this exposed fastener roof.
At below right you can see the fastener schedule for roofing panel edges along the roof valley. [St. Cuthberts church, built in 1874, was severely damaged in recent Christchurch area earthquakes.
While the church itself is not currently in use the congregation still meets nearby.]
Reader Question: (Sept 18, 2014) Jim said:
In a high wind area, how far apart should the screw lines be and how many screws should be in a row?
Reply: Fastener Screw Spacing Distances for Metal Roofing
Roofing manufacturers (such as Fabral in the U.S. and Dimond in New Zealand) give installation specifications for their product including screw fastener spacing schedules (and other data such as unsupported spans, unsupported overhang, and different fastener types).
Typically the sheet is fastened to every structural member (purlin, rafter, truss, etc). But that does not give the spacing distance between the fasteners along the structural member - that's what you must be asking.
Here are two common examples of metal fastener spacing for exposed fastener metal roofs. We give more detail in after introducing the wind speed topic:
Fabral roofing specifies 80 galvanized screws per square of steel material, for aluminum material, use stainless steel screws. - Fabral (2012)
Midwest Manufacturing specifies 75 screws per square of metal roofing. - Midwest (2014)
You don't say where you live, but wind speeds and wind zone ratings are indeed a critical consideration in choosing a roof covering material itself as well as its fastener schedule. For example in Welllington New Zealand, average windspeed (measured at the Wellington airport) is 29 km/h - compare that with the Windy City (Chicago) where average wind speed is a piddling 18 km/h. In Wellington New Zealand wind speeds top gale force most of the year (288 out of 365) recorded at 104 km/h in the spring of 2014. Wellington's highest reported wind gust speed was 248 km/h. - Fitzimons, (2011).
Exposed Metal Roof Fastener Schedule versus Wind Speeds or Wind Zones
The roof shown at above left is installed on a building in Dunedin, New Zealand.
Dimond, the New Zealand company I cite above and in our resources list below gives a table of number of fasteners per metre as a function of wind zone ranging from 1 fastener per meter to 4 fasteners per meter.
Low wind zone (32 m/sec): 1 fastener per meter
Medium wind zone (37 m/sec) : 2 fasteners per meter
High wind zone (44 m/sec) : 3 fasteners per meter
Severe wind zone (50 m/sec) : 4 fasteners per meter
Based on our example wind data above, had the roof at above left been installed in Wellington we'd have expected to see 4 fasteners per meter. [Click to enlarge any image]
Watch out: be sure to check the metal roof fastener schedule with the manufacturer of the roofing product you intend to use.
Also there are other fastener details that are important besides choosing an approved fastener type, such as an assumption that the fastener is driven in perpendicular to the roof surface (not on an angle).
Fabral provides additional metal roofing fastening advice for Exposed Fastener type roofs that generally agree with Steve Bliss's original material in the article above and which we excerpt here:
FABRAL can supply either screws or nails for fastening into dimension lumber. [The company notes that nails are not recommended
for fastening aluminum roofing because of thermal movement] Always use screws with solid sheathing. 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 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 the method being used
by the installer.
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.
Remove any metal filings created by the drilling action of the screws or pre drilling
of the holes to avoid rust staining on the panel surface.
Refer to the fastening schedules in this booklet for the correct fastener
locations. - Fabral (2012)
Exposed Fastener Metal Roofing Installation Manuals
Dimond Roofing, "Roofing and Cladding Systems Guide", Dimond Roofing Systems, Whangarei,
33 Rewarewa Rd,
Ph: 09 438 1539 Fax: 09 438 6525, , retrieved 9/25/2014, original source http://www.dimond.co.nz/filescont/downloads/roofing_manual_lite.pdf
Fabral, "Installation Instructions for Metal Panels", Fabral Corporation:
Lancaster PA, USA, www.fabral.com
Tel: 800-477-2741, Exposed fastener and concealed clip metal roofing
panels, retrieved 9/25/2014, original source http://www.fabral.com/wp-content/uploads/2013/11/ Storage%20&%20Install%20Guide%2011-2013.pdf
Metal Roofing Information & Product Sources
[Bold faced roofing suppliers in the list below provided technical information quoted or adapted in the article above - Ed.]
Modular metal shingle panels and standing seam panels
Dimond Roofing Systems, Tel: 0800 DIMOND, Website: http://www.dimond.co.nz The company has offices throughout both North Island and the South Island of New Zealand, of which we give just a few
Dimond Roofing Systems, Auckland,
48 Victoria St, Onehunga,
New Zealand, Ph: 09 634 0575 Fax: 09 634 6231 Dimond is New Zealand's largest manufacturer of steel roofing, cladding, structural and rainwater goods.
Decra Roofing Systems
Modular metal shingle, tile, and shake panels
Dura-Lok Roofing Systems
Modular metal roofing shingles with granular coating
Lancaster PA, USA, www.fabral.com
Tel: 800-477-2741, Exposed fastener and concealed clip metal roofing
Gerard Roofing Technologies
Modular metal shake and tile panels with granular
Modular metal roof-tile panels
Midwest Manufacturing, "Helpful Hints for Residential Steel Roofing", (2014), Midwest Manufacturing, 5311 Kane Road
Eau Claire, WI 54703 USA, Website: http://www.midwestmanufacturing.com, retrieved 9/25/2014, original source http://www.midwestmanufacturing.com/MidwestManufacturing/web/docs/pdf/HelpfulHints.pdf
Modular metal shingle, tile, and standing-seam panels
Modular metal shakes and standing seam panels
Zappone Manufacturing, website www.zappone.com/
Zappone Manufacturing, 2928 North Pittsburg St. Spokane, WA 99207
1-800-285-2677, Washington State Copper Roofing Supplier of
Copper scallop shingles, copper shingles, copper bay windows, vertical walls, aluminum roof shingles
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"Choosing Roofing," Jefferson Kolle, January 1995, No. 92, Fine Homebuilding, Taunton Press, 63 S. Main St., PO Box 5506, Newton CT 06470 - 800-888-8286 - see http://www.taunton.com/FineHomebuilding/ for the magazine's website and for subscription information.
 Follansbee Roofing, Follansbee WV 26037, Tel: 800-624-6906, website: www.follansbeeroofing.com and http://www.follansbeeroofing.com/products/TerneII.aspx Quoting Follansbee on TerneII properties:
Follansbee Steel is the only manufacturer of a pre-painted or natural Terne roof and is a leading supplier of metal roofs for new and retrofit commercial, institutional, residential and historic preservation projects.
Terne II - Classic Terne-Coated Steel
... is a new and improved version of historic Terne metal, ... Terne II has improved capability for resisting corrosion in all environments ... also has excellent formability, solderability, and affinity for paint ... without compromising mechanical characteristics. It can be used in flatlock, standing seam, vertical wall designs and virtually any other application in which original Terne has been used. It is strong and ductile, having high yield and tensile strengths as well as workability. This new material can easily be formed with conventional roofing tools.
With Terne II roofing, it is advisable to paint the material as soon as conditions permit. Oxide formation is slower than with the original Terne and the wait for proper painting conditions provides substantially less risk. The new material is coated with Follansbee's new ZT® alloy, a combination of zinc and tin. This coating is designed not only as a barrier but also to be anodic to the steel substrate and reduce the potential for oxidation before painting.
The traditional oil-based paints long required on original Terne are not recommended for application on Terne II. Follansbee's Rapidri paint with its faster drying time and ease of application is much superior to the old painting system. The Rapidri acrylic paints are aesthetically pleasing while offering enhanced durability and color retention. ...
Metal Roofing Alliance, E. 4142 Hwy 302, Belfair, WA 98528, Telephone:(360) 275-6164, Customer Support 410-534-6900, Email: firstname.lastname@example.org,
Website: www.metalroofing.com. Quoting:
The Metal Roofing Alliance was formed in 1998 by a small group of forward-thinking metal roofing manufacturers with the main goal of educating consumers about the many benefits of metal roofing. Since our inception, we've shown millions of people just how beautiful, durable and money-saving metal roofing can be for them. Over the years, our membership has grown to include paint companies, material suppliers, industry publications and more. Be sure to take advantage of all of the great resources our members offer.
The Metal Initiative, 4700 W. Lake Ave., Glenview, IL 60025, P:847.375.4785 Website: www.themetalinitiative.com/, Email: Louise Ristau email@example.com Quoting:
The Metal Initiative is a coalition of manufacturers, individuals and associations that have come together to provide information on the features and benefits of metal in construction. Carrying its message of metal primarily to the professional building owner community, The Metal Initiative seeks to gather and disseminate useful information for decision-makers.
Problems in Roofing Design, B. Harrison McCampbell, Butterworth Heineman, 1991 ISBN 0-7506-9162-X (available used)
Grapevine Design Guidelines - Web Search 07/12/2010
"Copy on file as - /roof/Asbestos-to-Zinc_Metal_Roofing_NPS.pdf - From Asbestos to Zinc, Roofing for Historic buildings, Metals - ", Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source:
"Copy on file as - /roof/Asbestos-to-Zinc_Metal_Roofing_NPS_3.pdf - From Asbestos to Zinc, Roofing for Historic buildings, Metals-part II, Coated Ferrous Metals: Iron, Lead, Zinc, Tin, Terne, Galvanized, Enameled Roofs - ", Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source:
"On file as /roof/Asbestos-to-Zinc_Metal_Roofing_NPS_2.pdf - From Asbestos to Zinc, Roofing for Historic buildings, Metals- Roofing Today - ", Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source:
"Copy on file as - /roof/Roofing_Historic_NPS.pdf">Roofing for Historic buildings - ", Sarah M. Sweetser, Preservation Brief 4, Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source:
"Copy on file as - /exterior/NPS_Preserv_Brief_16_Subs_Mtls.pdf">The Use of Substitute Materials on Historic Building Exteriors - ",
Sharon C. Park, AIA, Preservation Brief 16, Technical Preservation Services, National Park Service, U.S. Department of the Interior, web search 9./29.10, original source:
ARMA - Asphalt Roofing Manufacturer's Association - http://www.asphaltroofing.org/
750 National Press Building, 529 14th Street, NW, Washington, DC 20045, Tel: 202 / 207-0917
"Metal Roofing: 'Fixing' for Thermal Movement [ copy on file as /roof/Metal_Roof_Movement_NRCA.pdf ] - ", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] p. 72, NRCA
"Metal Roof Systems: Design Considerations for Snow and Ice [ copy on file as /roof/Metal_Roof_Snow_Ice_NRCA.pdf ] - ", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] p. 74, NRCA
"Steel [Roof] Decks: Issues for the 1990's [ copy on file as /roof/ Steel_Roof_Deck_Corrosion1_NRCA.pdf ] - ", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] p. 74, NRCA
"Steel [Roof] Deck Corrosion Bulletin, NRCA [ copy on file as /roof/Steel_Roof_Deck_Corrosion_NRCA.pdf ] - ", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] p. 58, NRCA
"The Many Aspects of Metal [Roof] Shingles [copy on file as Metal_shingles_NRCA.pdf ] - ", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] NRCA
NRCA - National Roofing Contractors Association - http://www.nrca.net/, 10255 W. Higgins Road, Suite 600,
Rosemont, IL 60018-5607, Tel: (847) 299-9070
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