Key design details & references for clay roofing tiles
Duralita & other clay roof tile alternative products
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Here we discuss clay tile roofing types, clay roofing tile inspection, tile roofing diagnosis, & tile roof repair. 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.
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.
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 the damage was due to foot traffic.
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.
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.
Books & Articles on Clay Tile Roof Inspection, Installation, Repair, Maintenance, & History
The books listed below can be found by using the "Roofing" link at the InspectAPedia Bookstore.
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.
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Carson Dunlop, Associates, 120 Carlton Street Suite 407, Toronto ON M5A 4K2Toronto. (416) 964-9415 1-800-268-7070 info@carsondunlop.com. Thanks to Alan Carson and Bob Dunlop, for permission to use illustrations from their publication, The Illustrated Home which illustrates construction details and building components. Carson Dunlop provides home inspection education including the ASHI-adopted Home Inspection Training Program (home study course), publications such as the Home Reference Book, report writing materials including the Horizon report writer, and home inspection services. Alan Carson is a past president of ASHI, the American Society of Home Inspectors.
The Carson Dunlop home study course for home inspectors can be examined at the company's website at http://www.carsondunlop.com/Inspectors/hss.htm
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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