Carson Dunlop Associates's illustrations (below) compare an EPDM roof membrane installation and a PVC roof membrane installation.
[Click to enlarge any image]
Materials & Installation Advice for Walkable Roofing Membranes
As explained in Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) , chapter on BEST ROOFING PRACTICES:
For rooftops that will also serve as decks (see “Rooftop
Decks,” [online version coming] page 150 in the printed text Best Practices Guide to Residential Construction), one option is to use a roofing material
designed for foot traffic.
Duradek (Duradek U.S. Inc.) is a
sheet vinyl membrane similar to Hypalon but with a nonskid
wear surface. It was developed over 25 years ago for
waterproofing decks, balconies, and outdoor living spaces.
For use over a living space, the manufacturer recommends
its 60-mil Ultra series, which is warranted against leakage
for 10 years.
Duradek is made of reinforced PVC sheet with heat
stabilizers and additives for resistance to fire, UV degradation,
and mildew. The wear surface is textured for slip
resistance and available in a variety of colors.
Installation Tips for Walk-On Roofs
Installation is similar to other single plies
and must be done by factory-certified contractors. The
membrane glues to almost any clean substrate with either
a proprietary contact cement or a special water-based
adhesive applied with a notched trowel.
Seams are heat
welded with a heat gun, the most critical step. Like other
single-ply membranes, the material is self-flashing at abutting
walls and penetrations.
Pros and Cons of Duradek Walkable Roofing Membranes
Duradek creates an attractive and
durable no-skid deck surface that can withstand
normal wear and tear, direct sun exposure, high winds, and
freeze-thaw cycles. However, because the membrane is
also the wear surface, it can be damaged by cigarette
burns, punctures, and heavy abrasion.
- - Adapted with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) .
Other Examples of Walk-on Roof Surfaces Using Pavers, Boards, Plank Walkways
At above left is an example of an awkward roof hatch access onto a walk-on low-slope roofing.
Access is necessary for HVAC system maintenance, roof drain maintenance, etc. Notice also the black roofing mastic patching around the rooftop HVAC ductwork - I expect there have been leaks into the duct system and possible mold contamination therein.
At above right is an on-roof service stair on a low slope roof at the Castle Point New York Veterans Administration health facility. Notice that raised curbs have been placed at mechanicals and at the stair bottom. See the photo at below left for details.
Below is an older walk-on roof surface: painted canvas nailed on a walk-out balcony roof in Newburgh, New York. Well, ok, it used to be a walk-on roof surface. At this inspection the canvas was worn, missing in some areas, and the roof was of course leaking.
Shown below is the painted-canvas surface of a pre-1900 walk-on roof-balcony surface on the same building as illustrated above.
Below is a walk-on roof balcony from another 19th century New York building that was covered in interlocking copper shingles soldered together.
How about a "drive-on" roof surface. Below we illustrate the roof of a home along the Hudson River in New York.
And below is a New York City rooftop deck constructed over a flat membrane roof surface.
...
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Citations & References
In addition to any citations in the article above, a full list is available on request.
Mark Cramer Inspection Services Mark Cramer, Tampa Florida, Mr. Cramer is a past president of ASHI, the American Society of Home Inspectors and is a Florida home inspector and home inspection educator. Mr. Cramer serves on the ASHI Home Inspection Standards. Contact Mark Cramer at: 727-595-4211 mark@BestTampaInspector.com
John Cranor [Website: /www.house-whisperer.com ] is an ASHI member and a home inspector (The House Whisperer) is located in Glen Allen, VA 23060. He is also a contributor to InspectApedia.com in several technical areas such as plumbing and appliances (dryer vents). Contact Mr. Cranor at 804-873-8534 or by Email: johncranor@verizon.net
"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.
Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF] ISBN-10: 0471331724
ISBN-13: 978-0471331728
Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008)
ISBN-10: 1405161035
ISBN-13: 978-1405161039
Historic Preservation Technology: A Primer, Robert A. Young, Wiley (March 21, 2008)
ISBN-10: 0471788368
ISBN-13: 978-0471788362
Problems in Roofing Design, B. Harrison McCampbell, Butterworth Heineman, 1991 ISBN 0-7506-9162-X (available used)
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.
Best Practices Guide to Residential Construction, by Steven Bliss. John Wiley & Sons, 2006. ISBN-10: 0471648361, ISBN-13: 978-0471648369, Hardcover: 320 pages, available from Amazon.com and also Wiley.com. See our book review of this publication.
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
Asphalt Roofing Residential Manual from ARMA the Asphalt Roofing Manufacturers Association Website https://www.asphaltroofing.org/product/residential-asphalt-roofing-manual/ ,
Building Pathology, Deterioration, Diagnostics, and Intervention, Samuel Y. Harris, P.E., AIA, Esq., ISBN 0-471-33172-4, John Wiley & Sons, 2001 [General building science-DF] ISBN-10: 0471331724
ISBN-13: 978-0471331728
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
Handbook of Building Crafts in Conservation, Jack Bower, Ed.,
Van Nostrand Reinhold Company, NY 1981 ISBN 0-442-2135-3 Library of
Congress Catalog Card Nr. 81-50643.
Historic Preservation Technology: A Primer, Robert A. Young, Wiley (March 21, 2008)
ISBN-10: 0471788368
ISBN-13: 978-0471788362
Historic Slate Roofs : With How-to Info and Specifications, Tina Skinner (Ed), Schiffer Publishing, 2008, ISBN-10: 0764330012
, ISBN-13: 978-0764330018
Roof failure causes in depth (and specific methods for avoiding them)
Roof design fundamentals and flourishes, based on voluminous industry research and experience
New technologies and materials -- using them safely and correctly
Comprehensive coverage of all major roofing systems
pecifications, inspection, and maintenance tools for roofing work
In addition to citations & references found in this article, see the research citations given at the end of the related articles found at our suggested
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: info@carsondunlop.com. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
Carson Dunlop Associates provides extensive home inspection education and report writing material. In gratitude we provide links to tsome Carson Dunlop Associates products and services.