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This website tells readers how to identify fragile or unsafe roof surfaces, when to stay off of them, how to repair them.
By listing common causes of asphalt roof shingle failures and how to recognize them, building owners
and roofing contractors may also be able to reduce the occurrence of asphalt roof shingle storage, handling, and installation
errors that affect roof life.
Walking on some roofs causes damage: The photograph at the top of this page shows what happened when an inspector stepped on the fragile corner
of an asphalt roof shingle. This pattern of breakage traced his footprints right up the roof to the chimney and back down the other side.
These are the very "footprints of damage" which we have reported in some other articles on fragile, old, worn roof shingles.
This "failed" roof was not leaking until the fellow who was asked to inspect it
walked across this fragile surface. From a ladder at the roof edge one could clearly see the virtual
footprints of broken shingle edges where the "inspector" had walked. In this case the "inspector" was a roofing
contractor who came back down to the ground and told the home owner that she needed a new roof right away.
She was
upset because her ASHI-certified home inspector had said that the thought she could use the roof
for another two to five years. Our opinion was that she did need a new roof very soon but that had not
been the case until "bigfoot" had stomped all over it.
Worn out fragile roofs: The roof in the photograph shown here is one which is worn out, probably already leaking
at least into the layers of roofing material, and it is so fragile that it should not be walked-on.
I would stay off of worn, brittle, or cupped-shingle roofs, particularly in cold weather (shingles are more likely to break).
If we absolutely have to walk on such a roof, we would tiptoe carefully, avoiding stepping on the raised or cupped shingle
sections, or if doing repairs, we would prop a ladder up off of the roof surface and work from that scaffold as is sometimes done
with slate or other fragile roof surface repairs.
Guidelines for Direct Walking-On Inspection of Various Roof Surfaces & Roof Conditions
Some home inspectors reduce their workload and speed the the job by asserting that they do not walk on any
roof surface under any condition, citing reasons of safety or fear of damaging the roof surface. But expert
inspectors generally agree that there are many roof areas, conditions, and important roof defects, even
total roof failure (such as thermal splitting), that are simply not visible except direct access to the
roof edge (by ladder or other means) or by walking on the roof.
Watch out: Do not try to walk on any roof which is: too high, steep, wet, slippery, fragile, or covered with loose mineral granules, or other loose roof surface debris - such roofs are not suited for safe access. Do not walk on any roof which
is installed over an incomplete, damaged, or rotted surface, as you might, like my helper on one roofing job, fall right
through the roof surface!
Advice About Walking on & Inspecting Asphalt Shingle Roofs
We do not walk directly on any asphalt shingle roof that has one or more of these hazards:
Roof is uncomfortable or feels unsafe or too fragile for any reason, in the opinion of the inspector
Steep pitch roofs - judgement of the inspector
High roofs - judgement of the inspector
Fragile roofs - judgement of the inspector
Wet, icy, snowy roofs - judgement of the inspector
Roofs with curled, cracked, or broken shingles - judgement of the inspector
Roofs for which there is not ready, safe access - judgement of the inspector
Loose mineral granules on an asphalt shingle or roll roofing roof surface, are dangerous and can cause the inspector to slip and fall off of the roof, regardless of the cause of loose material: whether because the roof is brand new (initial granule loss due to wear during installation) or old (mineral granules are loose because of age and loss of adhesion, weather exposure, or foot traffic).
Inspecting at ground level (photo above left) may show evidence of severe roof granule loss even before the inspector, owner, or roofing contractor has placed a ladder at the roof edge for a closer-look. From the roof edge you may see a gutter with a half inch or even more of mineral granules (above right). The two times we see asphalt roof shingle mineral granules on the ground or in gutters in quantity is at brand new asphalt shingle roofs, or at older, damaged, worn roofs whereon granules have lost their adhesion to the shingle by weather, age, foot traffic, hail, or other damage.
The determination of the safety and reasonableness of inspection method of any roof (or any other building
component) is the sole responsibility of the building inspector, with the exception that the building owner also has the right to ask that the inspector
omit or not access any building component or system.
The inspector is required in all cases to describe how an inspection was performed or
if it was not performed, to explain why and to explain the implications of this to his or her client.
Advice About Inspecting & Walking on Cement Asbestos or Fiber Cement Roofs
Cement asbestos roof shingles: these shingles are as fragile as slate; it's best to stay off of this surface. Though we've walked
carefully on a few such roofs it's easy to damage them. See our inspection advice at ASBESTOS CEMENT & FIBER CEMENT ROOFING and our advice about tile and slate roof inspections found in this document (below).
Advice for Walking on & Inspecting Clay Tile Roofs
To prevent breakage, walk on tiles with extreme caution.
Profile tile and lightweight tile are the most vulnerable,
and concrete tiles are more fragile when they are freshly
manufactured or “green.” If possible, place antennas and
other roof-mounted equipment where it is easy to access
without crossing many tiles.
When it is necessary to walk
on tiles, step only on the head-lap (lower 3 inches) of each
tile. With Mission- or S-tiles, it is best to step across two
tiles at once to distribute the weight. When significant
rooftop work is required, place plywood over the tile to
distribute the load.
Watch out: our own experience is that it is absolutely impossible to walk on many clay tile roofs without damaging them, particularly soft clay such as the roof type used in Latin America (our photo at left).
For these roofs contractors have to remove sufficient clay tiles to provide a walking area. The removed tiles are replaced as the worker is leaving the work area of the roof.
Below we show two photos of a low slope (leaky) flat shingle-style clay tile roof on a New York Home. The ease of access meant that this roof was walked-on by someone (not us) who broke many clay tiles. You'll also notice the flattened metal tabs that were intended to hold replacement tiles in place. The tabs appear to have been bent flat by snow sliding down the roof, thus permitting clay tiles to begin to move as well (see the loose tile in the center of our photo at below left).
On some other fragile but not totally fragile roofs such as slate roofs, cement tile, cement-asbestos, fiber cement, and hard-fired ceramic clay tile roofs, contractors suspend a ladder over the roof surface, hanging it from the ridge, and cushioning it off of the roof surface using foam or insulation padding, or contractors work from scaffolding. - Ed.
See ROOF INSPECTION SAFETY & LIMITS where we describe roof safety and roof damage issues when inspecting, repairing, or otherwise walking on other roof materials such as asphalt, slate, wood roofs.
Advice for Inspecting Other Fragile or Unsafe Roof Surfaces
Cupped roof shingles: stay off in cold weather; inspect the shingles from the roof edge, from upper building
windows, or if the roof must be walked-on, step carefully in the cupped portions on tiptoe, avoiding stepping
on the raised curled portions of the shingles as otherwise you'll break off large corners and may lead to an immediate
need for re-roofing. If the shingles are also brittle, even in
warm weather, do not walk on the roof. See CUPPING ASPHALT SHINGLES
Cracked roof shingles: vary in fragility, depending on shingle age and reason for cracking. Some "cracked" roof surfaces
such as roofs damaged by thermal splitting, are not likely to be further damaged by careful direct inspection by walking their surfaces. See CRACKS in FIBERGLASS SHINGLES
Curled roof shingles: as with cupped shingles, stay off in cold weather; inspect the shingles from the roof edge, from upper building
windows, or if the roof must be walked-on, step carefully on the flat portions of the shingle, on tiptoe, avoiding stepping
on the raised curled edges of the shingles as otherwise you'll break off the edges. If the shingles are also brittle, even in
warm weather, do not walk on the roof. See CURLING ASPHALT SHINGLES
Fishmouthed roof shingles: are fragile and may be damaged if you step on the raised portion of shingle. If the fishmouthing
is on a fairly new roof and the shingles are not otherwise brittle it may be possible to walk on such a surface. See FISHMOUTHING ASPHALT SHINGLES
Low-slope or single membrane roofs: can often be safely walked-on but beware of fragile, worn roll roofing which may
be damaged by careless foot traffic, and beware of raised blisters, ridges, wrinkles which can also be damaged by careless
walking.
Advice for Walking on or Inspecting Metal Roofs
Metal roof surfaces: can be walked-on provided
(1) the roof is not too steep and
(2) the metal roofing was installed
over closely-spaced nailers or sheathing. Beware that some metal roofs may be installed directly over rafters and widely
spaced horizontal nailers, and may be fragile or subject to denting.
Do not step on raised seams or other flashing areas
that may be damaged; beware, metal roofs are very slippery when wet. The metal roof in the right-hand photo above was high, steep, and
slippery. We would not consider walking on such a surface.
Advice About Walking on & Inspecting Slate Roofs
Slate roofs are fragile and are likely to be damaged by foot traffic;
it's best to stay off of slate roof surfaces during a building inspection. See
SLATE ROOF INSPECTION PROCEDURE for details.
Inspectors should be cautious in evaluating any roof condition to avoid failing the roof material
itself when leaks are confined to flashing areas.
Watch out: our own experience is that it is absolutely impossible to walk directly on slate roofs without damaging them, particularly if the slates are worn, loose, damaged. And walking on such surfaces is unsafe.
On some other fragile but not totally fragile roofs such as slate roofs, cement tile, cement-asbestos, fiber cement, and hard-fired ceramic clay tile roofs, contractors suspend a ladder over the roof surface, hanging it from the ridge, and cushioning it off of the roof surface using foam or insulation padding, or contractors work from scaffolding.
Our photo (above left) shows a slate roof being replaced in Duluth, MN. Notice the pairs of ladders that are used to install new slates without walking on this roof surface. The ladders address both a steep slope falling hazard and the probable damage to the slates from foot traffic.
Advice for Walking on & Inspecting Wood shingle roofs:
Wood shingle or shake roofs such as shown in our photograph are fragile and will be damaged by any foot traffic.
We've walked on new, good-condition wood shingle roofs but they are easily damaged
by foot traffic which can cause splits in the shingles. In addition
wood shingles are often slippery and dangerous to walk on and absolutely slippery when wet.
Advice for Walking on or Inspecting Wet, Icy, Steep, Snow-Covered Roofs
Wet, icy, or snow covered roofs are unsafe to walk on in most circumstances, possibly excepting expert inspection of flat roofs with safe parapets or railings installed.
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Additional technical contributors & reference sources for this article are listed below.
Use links at the left of each page to navigate this document or to view other topics at this website.
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miss some important articles. See links at page left.
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. (727) 595-4211 mark@BestTampaInspector.com
Hankey and Brown home inspectors, Eden Prairie, MN, technical review by Roger Hankey, prior chairman, Standards Committee, American Society of Home Inspectors - ASHI. 952 829-0044 - hankeyandbrown.com
Arlene Puentes, a licensed home inspector, educator, and building failures researcher in Kingston, NY.
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. 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
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