This article series discusses best practices in the selection and installation of residential roofing. This article includes excerpts or adaptations from Best Practices Guide to Residential Construction, by Steven Bliss, courtesy of Wiley & Sons. Our roof top photo shows safety precautions in place while re-coating a roof in Oslo, Norway.
Watch out: one of the quickest ways to fall off of a metal roof is to try walking on it while painting the surface, stepping in wet paint. Speaking from experience in Dunnsville, VA. Also see the page top photo at this article for some rooftop safety precautions including scaffolding and fencing. - Ed.
While unpainted metal roofs are common on utility buildings
and some rustic homes, most homeowners prefer a
painted surface. In addition to improving the appearance, a
high-quality factory finish can significantly extend the life
of metal roofing.
The corrugated roofing at left (Hudson New York) was never painted.
In general, factory finishes are durable
and flexible enough to tolerate factory roll-forming and
bending on-site.
The best finishes carry decades-long
warranties against cracking and peeling, and “excessive”
chalking and fading (as defined by the manufacturer).
The
quality of the finish is determined by the type of resin and
the stability of the pigments.
Polyester-Resin Roof Paints for Metal Roofing
Polyester-resin paints are the least expensive
and are commonly used on exposed-fastener panels. These
have a medium to high gloss when applied, but they will
fade significantly within 5 to 7 years on surfaces exposed
to direct sun. Bright red, for example, may fade to pink.
Fading will be less noticeable on light colors, making them
a better choice. Warranties are typically for 3 to 5 years
and rarely cover fading or chalking.
Silicone-Modified Polyester Roof Coatings
SMPs (siliconemodified
polyesters) use polyester resins blended with silicone
additives to improve performance. In general, the
higher the silicone content, the more durable the finish.
These are available in medium- and high-gloss colors, and
they resist fading and chalking much better than standard
polyester paints. Warranties against excessive fading and
chalking typically run from 10 to 20 years, depending on
the formulation.
PVDF Fluoropolymer Resin Roof Paints
Based on a fluorocarbon-based resin
called PVDF, these are the most technically advanced and
most expensive finishes. Sold under the trade names Kynar
500® and Hylar 5000®, fluorocarbon-based paints provide
a smooth and dense medium-gloss finish that offers excellent
durability and long-lasting resistance to fading and
chalking, even under intense sun exposures.
The Teflon-like
coating also resists dirt retention and holds up better
in coastal environments than other finishes. The finish is
softer than SMPs, however, and can be damaged by the
roofing installers, if they are not careful. Typical warranties
run 20 years or greater, with 10- to 20-year protection
against excessive fading.
Use of Reflective Finishes for Metal Roofs to Reduce Building Air Conditioning Costs
Our photo (left) shows a very common practice: painting antiqu3e metal roofs with aluminized roof coatings to reduce rusting, improve roof life, and increase reflectivity to reduce heat gain in the building in hot sunny weather.
Watch out: some roof coatings and paints and particularly some roofing cements commonly used to "patch" old rusting or leaky metal roofs may work in the short run, but contain corrosive chemicals that actually speed further metal roof corrosion.
Be sure that the coating or patch material you use on a metal roof is approved for the metal surfaces to which it is being applied. In Newburgh NY we inspected the restoration of an historic home that had made extensive use of copper roof flashing.
The most severe corrosion had occurred where and after a bituminous flashing cement had been blobbed atop of copper flashing joints.
White metal roofs can reduce
cooling loads by as much as 30%, according to tests conducted
by the Florida Solar Energy Center. More modest
savings are now available with dark colors as well by using
metal shingles coated with special paints formulated to
selectively reflect the sun’s infrared and ultraviolet
radiation.
These “Hi-R” paints are now standard options
with Hylar/Kynar® finishes. Tests indicate that aluminum
shakes with a reflective brown finish reject 30% to 40% of
the total solar radiation compared to 67% for a white metal
roof.
Granular Coatings Used on Metal Roof Shingles
Some metal shingles are available
with a textured finish consisting of crushed stone or
ceramic granules blended into an acrylic resin. These are
applied over a special primer and sealed with a clear acrylic
sealer.
The multicolored granules give the appearance of an
asphalt shingle and protect against scratching from foot
traffic. The finishes also help protect against denting from
hail and help conceal any small dents.
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
Steven Bliss served as editorial director and co-publisher of The Journal of Light Construction for 16 years and previously as building technology editor for Progressive Builder and Solar Age magazines. He worked in the building trades as a carpenter and design/build contractor for more than ten years and holds a masters degree from the Harvard Graduate School of Education.
Excerpts from his recent book, Best Practices Guide to Residential Construction, Wiley (November 18, 2005) ISBN-10: 0471648361, ISBN-13: 978-0471648369, appear throughout this website, with permission and courtesy of Wiley & Sons. Best Practices Guide is available from the publisher, J. Wiley & Sons, and also at Amazon.com.
Critique, contributions wanted: Contact Us to suggest corrections or additions to articles at this website, and if you wish, to receive online listing and credit as a contributor. Particular thanks are due to the many experts and also consumers who read and critique technical articles at InspectAPedia.com.
Additional technical contributors & reference sources for this article are listed below.
Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
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
ASTM - ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA, 19428-2959 USA The ASTM standards listed below can be purchased in fulltext directly from http://www.astm.org/
Cedar Shake & Shingle Bureau, CSSB, U.S.: Sumas, WA 98295-1178, Tel: 604-820-7700, In Canada:
Cedar Shake and Shingle Bureau #2 - 7101 Horne Street, Mission, BC V2V 7A2 Tel: (604) 820-7700, E-mail: info@cedarbureau.com , website: http://www.cedarbureau.org/
Forest Products Laboratory, US FPL, One Gifford Pinchot Drive, Madison, WI 53726, Tel: (608) 231-9200, Email: mailroom_forest_products_laboratory@fs.fed.us608-231-9200, website: http://www.fpl.fs.fed.us/
NRCA - National Roofing Contractors Association - http://www.nrca.net/, 10255 W. Higgins Road, Suite 600,
Rosemont, IL 60018-5607, Tel: (847) 299-9070
UL - Underwriters Laboratories - http://www.ul.com/
2600 N.W. Lake Rd.
Camas, WA 98607-8542
Tel: 1.877.854.3577 / Fax: 1.360.817.6278
E-mail: cec.us@us.ul.com
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, 2010, $69.00 U.S., is available from Carson Dunlop, and from the InspectAPedia bookstore. The 2010 edition of the Home Reference Book 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. InspectAPedia.com ® author/editor Daniel Friedman is a contributing author. Field inspection worksheets are included at the back of the volume.
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.
Green Roof Plants: A Resource and Planting Guide, Edmund C. Snodgrass, Lucie L. Snodgrass, Timber Press, Incorporated, 2006, ISBN-10: 0881927872, ISBN-13: 978-0881927870. The text covers moisture needs, heat tolerance, hardiness, bloom color, foliage characteristics, and height of 350 species and cultivars.
Green Roof Construction and Maintenance, Kelley Luckett, McGraw-Hill Professional, 2009, ISBN-10: 007160880X, ISBN-13: 978-0071608800, quoting: Key questions to ask at each stage of the green building process Tested tips and techniques for successful structural design
Construction methods for new and existing buildings
Information on insulation, drainage, detailing, irrigation, and plant selection
Details on optimal soil formulation
Illustrations featuring various stages of construction
Best practices for green roof maintenance
A survey of environmental benefits, including evapo-transpiration, storm-water management, habitat restoration, and improvement of air quality
Tips on the LEED design and certification process
Considerations for assessing return on investment
Color photographs of successfully installed green roofs
Useful checklists, tables, and charts
Problems in Roofing Design, B. Harrison McCampbell, Butterworth Heineman, 1991 ISBN 0-7506-9162-X (available used)
Roofing The Right Way, Steven Bolt, McGraw-Hill Professional; 3rd Ed (1996), ISBN-10: 0070066507, ISBN-13: 978-0070066502
Slate Roofs, National Slate Association, 1926, reprinted 1977
by Vermont Structural Slate Co., Inc., Fair Haven, VT 05743, 802-265-4933/34. (We recommend this book if you can find it. It
has gone in and out of print on occasion.)
Roof Tiling & Slating, a Practical Guide, Kevin Taylor, Crowood Press (2008), ISBN 978-1847970237, If you have never fixed a roof tile or slate before but have wondered how to go about repairing or replacing them, then this is the book for you. Many of the technical books about roof tiling and slating are rather vague and conveniently ignore some of the trickier problems and how they can be resolved. In Roof Tiling and Slating, the author rejects this cautious approach. Kevin Taylor uses both his extensive knowledge of the trade and his ability to explain the subject in easily understandable terms, to demonstrate how to carry out the work safely to a high standard, using tried and tested methods.
This clay roof tile guide considers the various types of tiles, slates, and roofing materials on the market as well as their uses, how to estimate the required quantities, and where to buy them. It also discusses how to check and assess a roof and how to identify and rectify problems; describes how to efficiently "set out" roofs from small, simple jobs to larger and more complicated projects, thus making the work quicker, simpler, and neater; examines the correct and the incorrect ways of installing background materials such as underlay, battens, and valley liners; explains how to install interlocking tiles, plain tiles, and artificial and natural slates; covers both modern and traditional methods and skills, including cutting materials by hand without the assistance of power tools; and provides invaluable guidance on repairs and maintenance issues, and highlights common mistakes and how they can be avoided.
The author, Kevin Taylor, works for the National Federation of Roofing Contractors as a technical manager presenting technical advice and providing education and training for young roofers.
The Slate Roof Bible, Joseph Jenkins, www.jenkinsslate.com,
143 Forest Lane, PO Box 607, Grove City, PA 16127 - 866-641-7141 (We recommend this book).
Solar heating, radiative cooling and thermal movement: Their effects on built-up roofing (United States. National Bureau of Standards. Technical note), William C Cullen, Superintendent of Documents, U.S. Govt. Print. Off (1963), ASIN: B0007FTV2Q
"Weather-Resistive Barriers [copy on file as /interiors/Weather_Resistant_Barriers_DOE.pdf ] - ", how to select and install housewrap and other types of weather resistive barriers, U.S. DOE
Mobile View
