Asphalt Roll Roofing Installation, Defects, Repairs
- ROLL ROOFING, ASPHALT - CONTENTS: Asphalt based roll roofing installation, inspection, leaks, life expectancy. Definition of roll roofing materials, specifications, standards, applications. How and where should mineral granule coated roll roofing be used on buildings? What is the life expectancy of roll roofing
- ASPHALT ROOF SHINGLES - separate article, same material
- POST a QUESTION or READ FAQs about roll roofing
Roll roofing installation, inspection, troubleshooting, repairs: this article describes mineral-granule coated asphalt roll roofing roofing materials, choices, installations, inspection, defects, roofing repairs, and product sources. Our page top photo shows our client pointing to a low slope area on a roof where mineral-granule coated asphalt roll roofing was applied after shingles in that location had leaked repeatedly. Because mineral-granule-coated modified bitumen roofing can be mistaken for roll roofing, and vice versa, readers should also see MODIFIED BITUMEN ROOFING.
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Asphalt Roll Roofing Materials, Choices, Costs, Life Expectancy, Characteristics
As stated in Best Practices Guide to Residential Construction, chapter on BEST ROOFING PRACTICES:
Roll roofing is simplest product to install on a small section of lowslope
roof is 90-pound roll roofing.
This consists of a heavy,
asphalt-saturated organic or fiberglass felt with a granular
surface. Rolls are 36 inches wide and weigh 90 pounds.
Single-coverage roll roofing typically has a 2-inch lap with
exposed nails and is used mainly on utility structures.
Double-coverage roll roofing is installed with a full
19-inch lap joint, leaving a 17-inch exposure, with a 2-inch
Nails are concealed under the lap joints that are
sealed with asphalt lap cement. With two layers of protection,
double-coverage roll roofing is acceptable for small
roof areas and can be used on roofs as shallow as 1:12.
-- Adapted with permission from Best Practices Guide to Residential Construction.
In its earliest forms roll roofing consisted of sheets of felt canvas or cloth that were
impregnated with asphalt, then rolled flat along a low-slope or even some steeper sloped roofs with the material's long edge parallel to the building eaves.
Modern 90-pound asphalt roll roofing is built of mineral-coated fiberglass-reinforced mat or organic-mat (bituminous impregnated paper) material very similar to asphalt roof shingles, in 36-inch wide material sold in 36-foot long rolls. Roll roofing is coated on both sides with asphalt and its upper or exposed side is protected with mineral granules.
Common roll roofing material colors are white, brown, black. You may find some roofers referring to roll roofing as "90-pound felt" since a 36-foot roll of the material, able to cover about 100 sq.ft. (one roofing "square") weighs close to ninety pounds.
Tips For Buying Roll Roofing Materials
Our roll roofing material photo (left) shows that this roll was a bit out of round. When buying roll roofing avoid rolls that are squashed as they may be difficult to roll out smoothly (give the material time to relax and flatten before nailing).
Also avoid rolls whose ends are badly damaged as it may make for uneven or raised seams.
This is an inexpensive roofing material often installed (over 15# felt underlayment) by homeowners and do-it-yourself-ers.
Installing Roll Roofing for Maximum Life
Nonetheless roll roofing installations will have a longer life if installed according to the product manufacturer's instructions, nailed at proper intervals, and with seams properly sealed.
It's also important to install roll roofing over a smooth sound roof deck. If the roof decking sags, ponding on the roof surface after rain may reduce its life.
Overlapping strips of asphalt roll roofing are installed over the roof surfaces with overlapped edge joints sealed, usually with a heated asphalt compound, or cold-applied using a similar sealant that functions at lower temperatures.
Sketch (left) courtesy of Carson Dunlop Associates.
Probably in part because asphalt roll roofing is typically used on low slope and nearly flat roofs, it can have an anticipated wear life of less than ten years, often five years.
The life of roll roofing may be extended by coatings.
Common Problems on Roll-Roofing Covered Roofs
As Carson Dunlop's sketch (at left) illustrates,
- A common roll roofing problem includes wrinkles or bubbles.
- Granule loss and exposure of "bald spots" or cracking are common signs that roll roofing is at the end of its life
Not quite so common, but we also see misapplications of roll roofing such as:
- Running the roll roofing over a 90-degree angle and up the vertical surface of a parapet wall or chimney as "flashing"
- Running roll roofing with its seams parallel to the building gable ends
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Technical Reviewers & References
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- 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 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 804-747-7747 or by Email: firstname.lastname@example.org
- "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.
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
- 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
- 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.
- Asphalt Roofing Residential 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
- Building Pathology: Principles and Practice, David Watt, Wiley-Blackwell; 2 edition (March 7, 2008)
- Concrete Folded Plate Roofs, C. Wilby PhD BSc CEng FICE FIStructE (Author), Butterworth-Heinemann, 1998, ISBN-10: 0340662662, ISBN-13: 978-0340662663
- Concrete Shell Roofs, C. Wilby PhD BSc CEng FICE FIStructE (Author),
- Concrete Dome Roofs (Longman Concrete Design and Construction Series),
- 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
- 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)
- Historic Slate Roofs : With How-to Info and Specifications, Tina Skinner (Ed), Schiffer Publishing, 2008, ISBN-10: 0764330012
, ISBN-13: 978-0764330018
- Low Slope Roofing, Manual of, 4th Ed., C.W. Griffin, Richard Fricklas,
McGraw-Hill Professional; 4 edition, 2006, ISBN-10: 007145828X, ISBN-13: 978-0071458283
- 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
- Metal Roofing, an Illustrated Guide, R.A. Knowlton , [metal shingle roofs],
- 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.)
- 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).
- Slate Roofing in Canada (Studi4es in archaeology, architecture, and history),
- Smart Guide: Roofing: Step-by-Step Projects, Creative Homeowner (Ed), 2004, ISBN-10: 1580111491, ISBN-13: 978-1580111492
- Tile Roofs of Alfred: A Clay Tradition in Alfred NY
- "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
- Wood Shingle Roofs, Care and Maintenance of wood shingle and shake roofs(EC), Stanley S. Niemiec (out of print)