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Our page top photo shows clay roofing tiles installed in Patzcuaro, Mexico. Clay roofing tiles have been used in Europe, the Middle East, and Asia, since the Greek and Roman Empires, and the Americas since Europeans arrived there. This roofing material is costly to purchase and install, but it can have an indefinite life expectancy.
As we discussed at
SLATE ROOF INSPECTION & REPAIR, the fasteners or metal flashings on clay tile roofs are more likely to wear out than the tiles themselves. However clay tile roofs are often damaged by foot traffic, ice and snow, or by severe storms. Also see CLAY TILE ROOF STYLES, DESIGNS for detailed descriptions of different clay roof tile styles and characteristics, and see ROOFING TILE SHAPES & PROFILES for the basics of roof tile profiles and what they mean.
Real clay tile roofs compared with cosmetic clay tile roofs: The clay roof tile systems we discuss in this article series are "real" clay tile roofs on which the tiles themselves are intended to provide the water shedding and drainage necessary to form a dry covering over a building. "Cosmetic" clay tile roofs are commonly installed in some areas (Boca Raton, Florida) over a completely functional waterproof membrane. Cosmetic clay tile roofs also protect the roof membrane from deterioration from sunlight, but the tiles themselves are not forming the waterproof covering.
A Little History of Clay Roofing Tiles in the U.S.
Clay roof tiles have been used since Roman times, and throughout the history of North America as well. As NPS historic preservation expert Sweetser points out,
European settlers used clay tile for roofing as early as the mid-17th century; many pantiles (S-curved tiles), as well as flat roofing tiles, were used in Jamestown, Virginia. In some cities such as New York and Boston, clay was popularly used as a precaution against such fires as those that engulfed London in 1666 and scorched Boston in 1679.
Tile[s]roofs found in the mid-18th century Moravian settlements in Pennsylvania closely resembled those found in Germany. Typically, the tiles were 1415" long, 67" wide with a curved butt. A lug on the back allowed the tiles to hang on the lathing without nails or pegs. The tile surface was usually scored with finger marks to promote drainage. In the Southwest, the tile roofs of the Spanish missionaries (mission tiles) were first manufactured (ca. 1780) at the Mission San Antonio de Padua in California. These semicircular tiles were made by molding clay over sections of logs, and they were generally 22" long and tapered in width.
The plain or flat rectangular tiles most commonly used from the 17th through the beginning of the 19th century measured about 10" by 6" by 1/2," and had two holes at one end for a nail or peg fastener. Sometimes mortar was applied between the courses to secure the tiles in a heavy wind.
In the mid-19th century, tile roofs were often replaced by sheet-metal roofs, which were lighter and easier to install and maintain. However, by the turn of the century, the Romanesque Revival and Mission style buildings created a new demand and popularity for this picturesque roofing material.
To make tiles, moist clay is extruded through a die or cast
in a mold and then fired in a kiln until the clay “vitrifies,”
fusing the particles together. Complete vitrification will
create a strong tile with very low water absorption, which
protects tile from freeze-thaw damage in cold climates or
damage from salt air in coastal areas. Where regular
freeze-thaw cycling is expected, roof tiles should comply
with ASTM C1167 Grade 1, which allows minimal water
absorption. Grade II tile provides moderate resistance to
frost action, and Grade III tile is porous and should not be
used in freeze-thaw areas.
Clay roof tiles, typically 7" x 13" are 1/4" to 1/2" in thickness and are shaped in molds and fired in a kiln to 2000 degF to cause the clay to vitrify. The vitrification (glasification) process makes the tiles hard and waterproof by melting and fusing silicas and aluminas in the clay. Clay roofing tile surfaces may also be decorated with an embossed pattern to resemble wood, slate, or stone. Un-glazed tiles are terra-cotta red, a color provided by iron oxide in the clay.
Clay roof tiles may also be made with a colored glaze, adding both color and an additional layer of hard surface protection. While traditional clay tile glazing was performed by hand dipping and pouring glazing compound over the tiles, Carson Dunlop point out in their Home Study Course for home inspectors, since the 1970's glazing on clay tiles has been spray applied and the tile backs are left un-glazed, both reducing tile cost and permitting moisture to escape from the back surface of the tile.
Higher quality clay roofing tiles are kiln fired to a higher temperature, are harder, less porous, and thus more durable. Inexpensive clay roofing tiles that are fired to lower temperatures insufficient to achieve vitrification are soft, easy to break, and less water resistant.
Carson Dunlop's sketch (left) illustrates the traditional tapered mission style clay roof tiles, and at right, the less-rounded barrel-mission style clay roof tiles.
Carson Dunlop's sketch (left) illustrates the Spanish roofing tile that is roughly "S" shaped, including the pan or drainage trough on the left side of the tile and the raised tile surface on its right side. Variations of these interlocking tiles include a lower-profile "S" tile and also Greek and Roman clay roof tiles.
All of the rounded mission tile roofing materials need to be enclosed at the eaves or lower roof edge to avoid blowing rain and wind (wind-lift damage) and animal entry. Tile end closure is discussed at How clay roofing tiles are secured.
Our photo (left) and Carson Dunlop's sketch (above right) illustrate a typical interlocking roofing tile that is flat.
In our photo you can see metal tabs that mark the location of inserted replacement or repair clay tiles. The tabs should be bent up over the tile edges but appeared to have been flattened by snow sliding down the roof.
This clay tile roof was located near New York City. Lots of these tiles were broken, particularly on the low slope roof section: we suspected some of the clay tile roof damage was due to foot traffic.
See ROOF INSPECTION SAFETY & LIMITS where we provide more photographs of this roof (Walking on Clay Roofs) and This article explains roof safety and roof damage issues when inspecting, repairing, or otherwise walking on clay tiles as well as other roof materials such as asphalt, slate, and wood roofs.
We recommend against walking on clay tile roofs as you are likely to damage the roof leading to the need for costly repairs. Our photo of broken clay roof shingle-tiles (above right) was taken during an inspection made without walking on the roof surface - for obvious reasons: we didn't want to shoulder the blame for this damage. our photo of a tarred roof valley and damaged interlocking clay roof tiles (above left) was taken from a ladder at roof edge.
How Clay Roof Tiles are Secured On the Roof & Open Eaves Closed
The illustrations of of how clay roof tiles are secured (below left) and of typical eaves closure of the open ends of Spanish or mission style roof tiles was provided courtesy of Carson Dunlop Associates. Additional details are at CLAY TILE ROOF CONNECTIONS.
Duralita, an alternative to both clay roofing tiles as well as other fiber reinforced cement roofing products is produced in El Salvador and used widely throughout central america and north americ. Duralita is a series of brightly-colored cardboard-reinforced cement corrugated roofing products produced by the Duralita, manufacturer of the same name. From the ground Duralita resembles clay roofing tiles.
Panels of Duralita are secured using fiber or rubber washers and threaded rods or bolts.
Duralita tejalitas are sheets of reinforced concrete that are intended to resemble roof tiles.
Corrugated cardboard cement products of the same composition, Lámina, are sold in sheets of various sizes and similar colors.
You can see an installation of Duralita at the Posada del Bosque Encantado, a hotel operated by our acquaintance Terry Rubin who was kind enough to inform us about this product.
Other examples of corrugated roofing products (that do not look like clay roof tiles) can be seen at Corrugated Cement-Asbestos Roofing.
Santafe Tile has been a manufacturer of clay roof tiles for over 18 years, supplying Florida, Texas, North and South Carolina, Georgia, Mississippi, Tennessee and Hawaii. Website: www.santafetile.com, Contact: Andrea Pascual, Sales & Marketing Manager, 1-888-305-TILE (8453), Email: arodriguez@santafetile.com
Dow Building Products, website:
www.dow.com/buildingproducts
Tile Bond polyurethane foam tile adhesive
Duralita: produces cement & cardboard corrugated and clay tile-like roofing products: Duralita is a combination of cement and cardboard - see www.duralita.com/ Si tiene alguna pregunta, por favor escribanos a: sales@duralita.com -
El Salvador: +503 22.25.57.44 ext.31 USA +1 305.677.3597
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Duralita: produces cement & cardboard corrugated and clay tile-like roofing products: Duralita is a combination of cement and cardboard - see www.duralita.com/ Si tiene alguna pregunta, por favor escribanos a: sales@duralita.com -
El Salvador: +503 22.25.57.44 ext.31 USA +1 305.677.3597
"Tile Roofs in Snow Country: The Natural Choice For Aesthetics
and Durability
Proper planning and installation ensure a tile roof with elegance,
durability, and low maintenance for premier resort in Vail, Colorado", Mark Wennstedt, Source Products Group, 303 280-9595 - Web Search 07/12/2010 - Original Source http://pdfone.com/download/12_keyword-roof-shingles/tile-roofs-in-snow-country.pdf
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.
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).
"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
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.
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).
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
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