Standing Seam Metal Roof Systems

STANDING SEAM METAL ROOF INSTALLATION - Standing seam metal roof systems
Installation guide standing seam roofing
Flashings and Accessories for Standing Seam Metal Roofs
Snow guards or snow brakes on metal roofs
Best practices for standing seam metal roofs
Questions & Answers about standing seam metal roof installation, troubleshooting, repair
References

Click to Show or Hide Related Topics

InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.

This article explains the proper installation, fastening, and flashing details for standing seam metal roofs. Standing-seam roofing consists of individual panels that run the length of the roof with a high rib up each side of the panels. The ribs overlap and lock together, concealing the fasteners and giving the roofing its name.

Standing-Seam Metal Roofing Installation Practices & Details

This article series discusses best practices in the selection and installation of residential roofing. Also see SNOW GUARDS on SLATE & METAL ROOFS and see our metal roofing home page, METAL ROOFING and see CORRUGATED ROOFING and COPPER ROOFING, our roofing home page: ROOFING INSPECTION & REPAIR.

Adapted/paraphrased with permission from Best Practices Guide to Residential Construction, chapter on BEST ROOFING PRACTICES:

The hidden fasteners allow thermal movement in the panels and are less likely to leak than exposed fasteners. However, some trim pieces are still fastened with exposed screws.

The smooth surface of a standing-seam roof provides a cleaner appearance and is easier to keep clear of leaf debris than tile, wood, or other textured roofing surfaces. Also, it can be walked on when necessary. Snow slides off easily as well, making this a popular choice in high snow regions. The cost is generally 25% to 50% more than an exposed-fastener roof of similar materials.

Materials Used in Standing Seam Metal Roofs

Standing-seam panels are 8 to 24 inches wide and available in steel, copper, and aluminum with a wide array of finishes (discussed below). Stiffening ribs may be added to wider panels to reduce waviness (oil-canning). Thicknesses for quality residential applications are typically 24 or 26 gauge, but lighter and heavier stock is also available.

Standing seam metal roof installers can form panels on-site from coil stock with portable roll-forming equipment, or they can order factory-made panels from a growing number of metal roofing manufacturers. Most factory-made panels have snaptogether seams, eliminating the need for special crimping equipment used by site fabricators. In most cases, panels are fabricated to run from eaves to ridge, eliminated the need for end lap joints.

Clips vs. flange standing seam roof panel fastening methods. Standing-seam panels either have an integral screwing flange (through-fastener panels) or are installed with clips placed 20 to 24 inches on-center (Figure 2-42).

Clip systems are more costly to manufacture and to install, but they have better wind resistance and a higher water-lock at the seams.

Also, because the clips allow unlimited panel movement, panels can be fabricated to any length. The flange type should be limited to 40 feet for steel and 20 feet for aluminum for normal climate conditions.
Site vs. factory fabrication of standing seam metal roof panels. For those with the equipment, site fabrication provides flexibility and saves on shipping costs, which can be high.

Site fabricators can also produce matching flashings and accessories to match the specific needs of the job. Factory-made panels, on the other hand, offer consistent quality, as well as preformed flashings and fittings that simplify installation. Using factory-produced panels, however, requires detailed planning since every piece of roofing must be preordered to length.

Installation Specifications for Standing Seam Metal Roofs

On new homes, most panels are installed over a solid plywood deck with minimum No. 30 felt underlayment. Metal roofing manufacturers recommend plywood rather than OSB due to plywood’s better screwholding ability.

Install the felt with plastic cap nails rather than metal buttons, which can cause corrosion when in contact with the roofing panels (see GALVANIC SCALE & METAL CORROSION).

After installing the drip edge, install the first panel, making sure it is square to the bottom edge of the roof. If the roof is not square, pull the panel away from the rake so the first rib does not overhang the rake edge.

Later, the rake trim piece will cover any small discrepancies. If the panels have an integral screw flange, keep the screws just snug so the panels can move with temperature changes. The clips are designed to allow thermal movement.

The next panel fits over the first with an overlapping rib. Fit each panel to a line snapped up the roof, marking the edge of each panel. Without layout lines, the panels can build up an incremental error, throwing off the layout. As panels are installed and secured, the joints are easily locked together with hand pressure.

Traditional standingseam roofing required special motorized crimpers to lock the seams. While these are still used on some low-slope systems, most residential installations now use snap-together panels. Unless the layout works perfectly, the last panel will need to be cut along the opposite rake and bent with a hand seamer to form the end rib.

Reroofing Using Standing Seam Metal Roofs Over Other Roof Coverings?

Standing seam reroof over wood shingles (C) Daniel Friedman

Our standing seam barn roof re-roof photo (left) demonstrates that re-roofing with standing seam metal roofs over older buildings is a very old practice. In this case the barn roof originally was covered with wood shingles, installed when the barn was constructed in the late 19th century in upstate New York.

Many installers will not install standing-seam roofing over existing asphalt shingles since the rough surface will tend to bind the panels and cause “oil-canning,” as the panels move with temperature changes.

One option is to install the new metal roofing over 2x4 purlins nailed through the old roofing and shimmed to form an even plane. Follow manufacturer’s recommendations for spacing of purlins, typically no more than 24 inches on-center.

Flashing and Sealing Details for Standing Seam Metal Roofs

Manufacturers of preformed roofing panels provide eaves and rake flashings, ridge caps, and sidewall flashings in matching finishes, as well as coil stock for site fabrication. Many flashings are designed with hidden fasteners; others require exposed gasketed screws.

Figure 2-41: Metal Roof Flashing details (C) J Wiley, S Bliss

Typical standing seam metal roof flashing details are similar to those found in Figure 2-41 shown at left [click to enlarge and add details].

Follow manufacturers’ recommendations regarding which sealants to use for compatibility with the roofing (typically butyl tape, or gunnable terpolymer butyl or urethane sealant). In general, avoid acid-cure silicone (the type that smells like vinegar) as it can be corrosive to many metal finishes.

-- Adapted with permission from Best Practices Guide to Residential Construction.

Resources: Roofing Materials & Equipment Suppliers

Manufacturers

Metal Roofing

Classic Products www.classicroof.com Modular metal shingle panels and standing seam panels
Decra Roofing Systems www.decra.com Modular metal shingle, tile, and shake panels
Dura-Lok Roofing Systems www.duraloc.com Modular metal roofing shingles with granular coating
Fabral www.fabral.com Exposed fastener and concealed clip metal roofing panels
Gerard Roofing Technologies www.gerardusa.com Modular metal shake and tile panels with granular coating
Met-Tile www.met-tile.com Modular metal roof-tile panels
Atas International www.atas.com Modular metal shingle, tile, and standing-seam panels
Custom-Bilt Metals www.custombiltmetals.com 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

Venting Underlayments

Benjamin Obdyke www.benjaminobdyke.com Cedar Breather, a 3/8 -in.-thick matrix-type underlayment designed to provide ventilation and drainage space under wood roofing

More Information about Roofing Materials, Methods, Standards

Asphalt Roofing Manufacturers Association (ARMA) www.asphaltroofing.org

Cedar Shake and Shingle Bureau www.cedarbureau.org

Metal Roofing Alliance www.metalroofing.com

Tile Roofing Institute www.tileroofing.org

#######

-- Adapted with permission from Best Practices Guide to Residential Construction.

Frequently Asked Questions (FAQs) about installing & repairing a standing seam metal roof

...

Ask a Question or Search InspectApedia

Questions & answers or comments about standing seam metal roof installation, troubleshooting, repair.

Ask a Question or Enter Search Terms in the InspectApedia search box just below.

Technical Reviewers & References

Related Topics, found near the top of this page suggest articles closely related to this one.

Architectural elements: the technological revolution: Galvanized iron roof plates and corrugated sheets; cast iron facades, columns, door and window caps, ... (American historical catalog collection), Diana S Waite, available used out of Amazon.
"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.
[1] 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: support@metalroofing.com, 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 lristau@connect2amc.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.
Metal Roofing, an Illustrated Guide, R.A. Knowlton , [metal shingle roofs],
"Metal Roofing: 'Fixing' for Thermal Movement", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] p. 72, NRCA
"Metal Roof Systems: Design Considerations for Snow and Ice", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] p. 74, NRCA
"Steel [Roof] Decks: Issues for the 1990's", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] p. 74, NRCA
"Steel [Roof] Deck Corrosion Bulletin, NRCA", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] p. 58, NRCA
"The Many Aspects of Metal [Roof] Shingles", Thomas L. Smith, AIA, CRC., Professional Roofing, [date pending] NRCA
Copper Roofing, by CDA
Copper Roofing, Master specifications for copper roofing and sheet metal work in building construction: Institutional, commercial, industrial, I.E. Anderson, 1961 (hard to find)
Corrugated Iron, Building on the Frontier, Simon Holloway
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:
http://www.nps.gov/history/hps/tps/roofingexhibit/metals2.htm
"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:
http://www.nps.gov/history/hps/tps/roofingexhibit/metals.htm
"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:
http://www.nps.gov/history/hps/tps/roofingexhibit/roofingtoday.htm
"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:
http://www.nps.gov/history/hps/tps/briefs/brief04.htm
"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:
http://www.nps.gov/history/hps/tps/briefs/brief16.htm
"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

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume. Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.

Or choose the The Home Reference eBook for PCs, Macs, Kindle, iPad, iPhone, or Android Smart Phones. Special Offer: For a 5% discount on any number of copies of the Home Reference eBook purchased as a single order. Enter INSPECTAEHRB in the order payment page "Promo/Redemption" space.

Decks and Porches, the JLC Guide to, Best Practices for Outdoor Spaces, Steve Bliss (Editor), The Journal of Light Construction, Williston VT, 2010 ISBN 10: 1-928580-42-4, ISBN 13: 978-1-928580-42-3, available from Amazon.com
The Journal of Light Construction has generously given reprint permission to InspectAPedia.com for this article. All rights and contents are ©Journal of Light Construction and may not be reproduced in any form.
Architectural elements: the technological revolution: Galvanized iron roof plates and corrugated sheets; cast iron facades, columns, door and window caps, ... (American historical catalog collection), Diana S Waite, available used out of Amazon.
...


	InspectAPedia^®	Question? Just ask us!	InspectAPedia
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair

Question? Just ask us!

Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair

Standing Seam Metal Roof Systems (function() { var po = document.createElement('script'); po.type = 'text/javascript'; po.async = true; po.src = 'https://apis.google.com/js/plusone.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(po, s); })();