Identifying Common Problems And Failures
While clay roofing tiles themselves are most likely to deteriorate because of frost damage, a clay tile roof system most commonly fails due to the breakdown of the fastening system. As the wooden pegs that fastened the early tiles to hand-riven battens rotted, they were often replaced with iron nails which are themselves easily corroded by tannic acid from oak battens or sheathing. The deterioration of metal flashing, valleys, and gutters can also lead to the failure of a clay tile roof.
Another area of potential failure of a historic clay tile roof is the support system. Clay tiles are heavy and it is important that the roof structure be sound. If gutters and downspouts are allowed to fill with debris, water can back up and seep under roofing tiles, causing the eventual deterioration of roofing battens, the sheathing and fastening system, or even the roof’s structural members. During freezing weather, ice can build up under tiles and cause breakage during the freeze/thaw cycle. Thus, as with any type of roof, water and improperly maintained rainwater removal and drainage systems are also chief causes for the failure of historic clay tile roofs.
Although modern, machine-made clay tiles are more uniform in appearance than their handmade counterparts, they also have the potential for failure. Occasionally, entire batches of mass-produced tile can be defective.
How To Install A Clay Roof Tile
If youre looking to give your home a Spanish or Mediterranean look, a clay roof tile is the way to go. Aside from its elegant appearance, there are many other benefits that come along with clay roofing as well. Today we will discuss these benefits, as well as tell you how to install your own clay roof tile. So lets not waste another minute!
Selected Sources Of Clay Roofing Tiles
Boston Valley Terra Cotta
Corona, CA 91718 New clay roofing tiles, some suitable for historic buildings
Note: Measurements in this publication are given in both the U.S. CustomarySystem and International System for comparative purposes. Metricconversions are, in some cases, approximate and should not be relied uponfor preparing technical specifications.
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Understanding The Layers Of A Roof
Every single roof starts with a truss system. The truss system is the skeleton of the roof and are often crafted from wood. Most homes have wooden truss systems. Once the trusses are in place a deck is constructed of wood.
The deck is the platform that other roofing material is attached to. The deck is covered with a layer of protective materials to which the shingles or tiles are directly attached to in some cases. In other cases, the battens are installed, and the shingles, tiles or metal sheets are attached to the batten.
Ridge Or Hip Tiles Return To Top
At the roof ridge or hip, clay tile is usually attached to a raised stringer with nails and a small amount of mortar, elastic cement or mastic. The joint is sealed with a flexible flashing such as copper or lead. Ridge tiles are often somewhat larger and more decorative than the field tile utilized on the broad sections of the roof.
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Graduated & Tapered Roof Tiles
Roofing systems that include round towers or domed shaped roof sections require special tile.
Each tile must be crafted to fit in its spot on the curved surface of the roof.
Each roof tiles size and shape tapers to become smaller toward the top and wider at the bottom to create an architectural masterpiece.
The Basic Steps Of Clay Tile Roof Installation
- Assess your roof decking before attempting to walk on it. Fix any areas that show signs of rot or wear.
- Install your underlayment. This is important with clay tile roofing, as it substantially increases your roofs water-tightness.
- Use chalk to draw horizontal and vertical lines on your roof to serve as a guide, ensuring your clay roofing pattern stays consistent.
- Install drip-edge flashing, and gutters. Given the substantial life expectancy of a properly installed clay roof, use only the best quality metal for your flashing and gutters.
- Begin to lay the first course of your tiles. Follow manufacturers instructions, as every type and style of clay roofing may require a slightly different method. As with the flashing, use only the best quality metal nails that are corrosion resistant, lest you want your clay tile roofing to start falling off.
- Once your first course is attached, observe it from below to ensure it is straight. Clay roofing, as a natural material, can vary slightly in color, so rearrange the tiles now if you are unhappy with the color scheme.
- If you are happy with the result, continue laying successive courses until your roof is finished.
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Calculate The Roof Area
Once you know what kind of tiles you want to lay on your roof, you need to calculate the area that you wish to cover so that you know how many tiles you’re going to need. To calculate your roof area, you need to know the length of your roof which you can find out by measuring the length of the wall that sits beneath it.
Next, you need to find the roof slope height. You’ll find this number on the building plans that you obtained when you purchased your property, and if you can’t access the plans for some reason your local council should have this information. Now you’re ready to determine the roof area by applying the following formula
Roof Length x Roof Slope Height = Half Roof Area
For example, if the roof length is 8.7 m and the slope height is 6.98 m, half the roof area is 60.73 m2. The total roof area is double that amount, or 121.5 m2.
Historical Background Return To Top
The origin of clay roofing tile can be traced independently to two different parts of the world: China, during the Neolithic Age, beginning around 10,000 B.C. and the Middle East, a short time later. From these regions, the use of clay tile spread throughout Asia and Europe. Not only the ancient Egyptians and Babylonians, but also the Greeks and Romans roofed their buildings with clay tiles, and adaptations of their practice continue in Europe to the present. European settlers brought this roofing tradition to America where it was established in many places by the 17th century.
Tapered barrel clay roof tiles were custom made for the restoration of the 1820s Indian barracks at Mission Santa Cruz in California. Photo: NPS files.
Archeologists have recovered specimens of clay roofing tiles from the 1585 settlement of Roanoke Island in North Carolina. Clay tile was also used in the early English settlements in Jamestown, Virginia, and nearby St. Mary’s in Maryland. Clay roofing tiles were also used in the Spanish settlement of St. Augustine in Florida, and by both the French and Spanish in New Orleans.
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How To Install Clay Tiles
After installing the underlay, it’s time to install the metal flashing around chimneys, conduits, vents and where the roof meets a vertical wall. A 28 gauge corrosion-resistant flashing is recommended. Follow these simple steps to install your clay tiles:
Revival Styles Renew Interest In Clay Roofing Tiles Return To Top
The clay tile roof is important in defining the character of the c. 1917 Mission-style Grove Park Inn, Asheville, North Carolina. Photo: NPS files.
Clay tiles were promoted by the Centennial Exhibition in Philadelphia in 1876, which featured several prominent buildings with tile roofs, including a pavilion for the state of New Jersey roofed with clay tiles of local manufacture. Tile-making machines were first patented in the 1870s, and although much roofing tile continued to be made by hand, by the 1880s more and more factories were beginning to use machines. The development of the Romanesque Revival style of architecture in the 1890s further strengthened the role of clay roofing tiles as an American building material.
Alternative substitutes for clay tiles were also needed to meet this new demand. By about 1855, sheet metal roofs designed to replicate the patterns of clay tile were being produced. Usually painted a natural terra cotta color to emulate real clay tile, these sheet metal roofs became popular because they were cheaper and lighter, and easier to install than clay tile roofs.
Clay tiles emphasize the prominence of the peaked roofs of these late 19th century rowhouses. Photo: NPS files.
The popularity of clay tile roofing, and look-alike substitute roofing materials, continues in the 20th century, especially in areas of the South and West-most notably Florida and Californiawhere Mediterranean and Spanishinfluenced styles of architecture still predominate.
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The Shapes Of Early Clay Roof Tiles
The most common shapes of early clay roof tiles were flat and rectangular. They had two nail or peg holes at one end through which the tiles were anchored to the roof. Sometimes a strip of cement mortar was placed between the overlapping rows of tile to stop the tiles from being lifted in very high winds. There were also interlocking S shaped pan clay roof tiles that were favourites in the 18th century. These types of clay roof tiles were formed by moulding clay over tapered sections of logs. Generally referred to as pan, crooked, or Flemish tiles, these interlocking tiles were hung on roofing lath by means of a ridge or lug located on the upper part of the underside of each clay tile. Both flat and pan tile roofs were capped at the ridge with semicircular clay ridge tiles.
So no matter what type of clay roof tile you require, Heritage Clay Tiles Ltd will have the tile you need.
Faq: Should My Concrete Tile Roof Be Installed Using Foam Or Screws
When it comes to the installation of concrete roof tiles, the level of wind exposure a home or commercial project is subjected to will determine what fastening methods should be used. If your certified roofing contractor has presented you with the option of choosing either mechanical fasteners or foam, then the choice is ultimately yours! Here are a few key points of both options to help you with your decision.
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Field And Specialty Tile
The tiles that cover the majority of the flat surface of the roof are called field tile. Some roof shapes, particularly conical towers or turrets, require tiles of graduated sizes, and some shapes or patterns of field tile also require specially shaped finish tiles to complete the roof covering package. Other uniquely-shaped tiles were made to fit odd-shaped spaces and places including dormers and valleys, roof hips, rakes, ridges and corners. There are also finish tiles that fulfill certain needs, such as eave closures or clay plugs called “birdstops.” These are intended to keep out snow and rain, and birds from nesting in the voids under the bottom row of curved tiles. Different patterns and designs can also be created by combining, or mixing and matching flat tiles with dimensional tiles.
How Tiles Are Attached Return To Top
The method used to attach clay roofing tiles varies according to the shape, size and style of the particular tile. For the most part, traditional and modern methods of installing clay roofing tiles are very similar, except that modern practice always includes the use of wood sheathing and roofing felt. But most of the earliest clay roofing tiles were laid without benefit of wood sheathing and hung directly on roofing laths and battens that were nailed to the roof rafters this practice continued up into the mid-19th century in some regions. While this method of attachment allowed for plenty of ventilation, and made it easy to find leaks and make repairs, it also meant that the overall water-tightness of the roof depended entirely on the tiles themselves.
Projections on the underside of these replacement Spanish clay tiles help them adhere to the cement mortar on the roof sheathing. Photo: NPS files.
Gradually, the practice evolved of nailing roofing tiles directly onto continuous wood sheathing, or hanging them from “nibs” on horizontal lath that was attached to roof rafters or sheathing. Some kinds of tile, especially the later Mission or Barrel tiles were laid over vertical strips or battens nailed to the sheathing, or the tiles were fastened to wood purlins with copper wire.
These tapered barrel clay tiles were accurately reproduced from archeological materials found on site. Photo: NPS files.
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The Right Roofing Underlay
One of the most important considerations for installing clay tile is to have a great roofing underlay. The material used below the clay tile is a critical factor that will affect the tile’s durability. Normally, the underlay is made from asphalt-saturated roofing material covering all area below the tile clay cover. Ensure that it’s properly attached or installed or you can end up with overlying tiles pretty quickly. Install an extra layer near the roof edge and in valleys to protect the surface even more. As a minimum, cover all decks with two layers of No. 30 asphalt-impregnated roofing felt or one layer of No. 43 coated base sheet.
New Hip And Ridge Requirements
Mortar’s weakness was further highlighted in 2004 by problems with hip and ridge tiles. The 1997 code revisions had simply neglected these. “Trim tiles had been treated as decorative accessories, so they were not adequately addressed ,” notes Olson. He reports that many roofers were still setting hip and ridge tiles on a bed of mortar, even where they had nailed or screwed the field tiles. Over time, the mortar’s grip on the hip and ridge tiles weakened, leaving them without secure attachment. “They would blow off and become airborne, bouncing across the roof plane, breaking field tiles, and causing other structural damage.” This happened even on homes built to current code standards and even on homes far enough from the beach to see considerably lower wind speeds. “We realized that something had to be done,” Olson notes.
Tiles properly secured with adhesive foam withstood the onslaught of Hurricane Charley over Port Charlotte Harbor, Fla., in August 2004. The only weak link was the rake detail. Best practice calls for a rake board and battens, as detailed in the illustration below.
Two-piece barrel profiles require a foam pad for the bottom tile and a double pad for the overlapping tile, as shown. In wind zones above 110 mph, exposures B and C, apply foam adhesive pad 1″W x 1″H x 8″L per ASCE 7-98. The also recommends ridge boards to secure ridge caps. Best practice calls for nose clips to secure the eaves edge, which is most vulnerable to wind uplift.
Types Of Roof Batten Systems
While roof battens are most commonly made of metal or wood, they can be made of other materials like plastic or composite. There are several different types of batten, some combine two materials to get the needed affect.
For example, elevated battens are standard wood battens that have a block of plastic attached to the underside to elevate the batten to a certain predetermined height. The elevated batten is used to help increase energy efficiency.
Elevated battens are typically used with tile roofs. They allow air flow, and prevent heat absorbed by the tiles to stay off the underlayment and keeps it from transferring into the attic below. The space created by the elevated batten is a natural form of insulation. It also has the added benefit of keeping moisture off the roof deck. These types of battens are more expensive then other batten types.
Traditional wood battens are a standard size of 1x2x4 and are constructed of a hardwood. Metal battens are used with metal roof panels. Plastic battens have also made the scene in the last decade but are used far less often than the other types of battens.
Do Roof Tiles Need To Be Nailed Down
It is not necessary to nail every single tile to the battens. Every tile of the two rows at the eaves, those up the verges, and along the two rows of the ridge should be nailed, but beyond that it is only necessary to nail every fifth tile horizontally and every third tile as you move up the roof.
Should ridge tiles be cemented on?
It should have cement put underneath and then once laid into position the ridge tile should be pointed on the outside to fix it to the last row of tiles. Long before a ridge tile blows off you would see this mortar coming loose in our case it took 25 years we heard it rolling down the roof during high winds.
