How To Repair Barrel Tile Roof
Preservation Briefs
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PRESERVATION BRIEFS
30
Historic clay tile roof. Photograph: NPS files.
The Preservation and Repair of
Historic Clay Tile Roofs
Anne E. Grimmer and Paul K. Williams
Clay tiles are one of the nigh distinctive and decorative historic roofing materials because of their great variety of shapes, colors, profiles, patterns, and textures. Traditionally, clay tiles were formed by hand, and after by motorcar extrusion of natural clay, textured or glazed with color, and fired in high-temperature kilns. The unique visual qualities of a clay tile roof often make it a prominent feature in defining the overall character of a historic edifice. The significance and inherently fragile nature of celebrated tile roofs dictate that special intendance and precaution exist taken to preserve and repair them.
Clay tile was a popular roofing fabric for residential structures during the Romanesque Revival period. Photograph: NPS files.
Clay tile has one of the longest life expectancies amidst historic roofing materials—mostly about 100 years, and often several hundred. Yet, a regularly scheduled maintenance program is necessary to prolong the life of any roofing organization. A consummate internal and external inspection of the roof structure and the roof covering is recommended to determine condition, potential causes of failure, or source of leaks, and will help in developing a program for the preservation and repair of the tile roof. Before initiating any repair work on historic clay tile roofs, information technology is important to identify those qualities important in contributing to the historic significance and character of the edifice.
This Brief will review the history of clay roofing tiles and volition include a description of the many types and shapes of historic tiles, as well as their different methods of attachment. It will conclude with full general guidance for the celebrated property owner or building manager on how to plan and carry out a project involving the repair and selected replacement of historic clay roofing tiles. Repair of historic clay tile roofs is non a job for amateurs; it should be undertaken merely by professional roofers experienced in working with clay tile roofs.
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 curt time later. From these regions, the use of clay tile spread throughout Asia and Europe. Non only the ancient Egyptians and Babylonians, but also the Greeks and Romans roofed their buildings with clay tiles, and adaptations of their practice proceed 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 fabricated 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 likewise used in the early English language 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.
Dutch settlers on the e coast first imported dirt tiles from Holland. By 1650, they had established their own full-scale production of clay tiles in the upper Hudson River Valley, shipping tiles south to New Amsterdam. Several tile manufacturing operations were in business effectually the time of the American Revolution, offering both colored and glazed tile and unglazed natural terra-cotta tile in the New York City area, and in neighboring New Jersey. A 1774 New York newspaper advertised the availability of locally produced, glazed and unglazed pantiles for sale that were guaranteed to "stand whatever weather." On the due west declension clay tile was first manufactured in wooden molds in 1780 at Mission San Antonio de Padua in California past Indian neophytes under the direction of Spanish missionaries.
By far the about pregnant factor in popularizing clay covering tiles during the Colonial menses in America was the concern with fire. Devastating fires in London, 1666, and Boston in 1679, prompted the establishment of edifice and fire codes in New York and Boston. These burn down codes, which remained in upshot for virtually two centuries, encouraged the use of tile for roofs, especially in urban areas, because of its fireproof qualities. Dirt roofing tile was also preferred considering of its durability, ease of maintenance, and lack of thermal electrical conductivity.
Although more efficient product methods had lowered the cost of clay tile, its use began to decline in much of the northeastern United states during the 2d quarter of the 19th century. In almost areas outside city-designated fire districts, wood shingles were used widely; they were more affordable and much lighter, and required less heavy and less expensive roof framing. In addition, new fire-resistant materials were becoming available that could be used for roofing, including slate, and metals such as copper, iron, tin-plate, zinc, and galvanized iron. Many of the metal roofing materials could be installed at a fraction of the cost and weight of clay tile. Even the advent of dirt tile was no longer stylish, and by the 1830s clay roofing tiles had slipped temporarily out of popularity in many parts of the country.
Revival Styles Renew Interest in Clay Roofing Tiles return to top ▲
The dirt tile roof is of import in defining the character of the c. 1917 Mission-style Grove Park Inn, Asheville, Due north Carolina. Photo: NPS files.
By the mid-19th century, the introduction of the Italianate Villa way of architecture in the United States prompted a new involvement in clay tiles for roofing. This had the effect of revitalizing the clay tile manufacturing industry, and past the 1870s, new factories were in business organisation, including large operations in Akron, Ohio, and Baltimore, Maryland.
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 industry. Tile-making machines were first patented in the 1870s, and although much roofing tile continued to be made past mitt, by the 1880s more and more factories were kickoff to use machines. The evolution of the Romanesque Revival style of architecture in the 1890s further strengthened the role of clay covering tiles as an American building material.
Culling substitutes for dirt tiles were also needed to run across this new demand. By about 1855, sail metal roofs designed to replicate the patterns of clay tile were being produced. Usually painted a natural terracotta color to emulate real clay tile, these canvas 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. Photograph: NPS files.
Clay roofing tiles fell out of fashion again for a short time at the stop of the 19th century, but once more gained credence in the 20th century, due primarily to the popularity of the Romantic Revival architectural styles, including Mission, Spanish, Mediterranean, Georgian and Renaissance Revival in which dirt tile roofs featured prominently. With the availability of machines capable of extruding dirt in a variety of forms in large quantities, clay tiles became more readily bachelor across the nation. More regional manufacturing plants were established in areas with large natural deposits of clay, including Alfred, New York; New Lexington, Ohio; Lincoln, California; and Atlanta, Georgia; besides as Indiana, Illinois and Kansas.
The popularity of dirt tile roofing, and expect-alike substitute roofing materials, continues in the 20th century, especially in areas of the S and Westward-well-nigh notably Florida and California—where Mediterranean and Spanish—influenced styles of architecture nonetheless predominate.
Early on Tiles return to pinnacle ▲
During the 17th and 18th centuries the most common type of clay roofing tiles used in America were flat and rectangular. They measured approximately ten" ten 6" ten Ω" (25cm x 15cm x 1.25cm), and had two nail or peg holes at one end through which they were anchored to the roofing laths. Sometimes a strip of mortar was placed between the overlapping rows of tile to forbid the tiles from lifting in high winds. In add-on to apartment tiles, interlocking S-shaped pantiles were also used in the 18th century. These were formed past molding clay over tapered sections of logs, and were generally quite large. Alternately termed pan, crooked, or Flemish tiles, and measuring approximately 14 Ω" ten 9 Ω" (37cm x 24cm), these interlocking tiles were hung on roofing board by means of a ridge or lug located on the upper function of the underside of each tile. Both plainly (flat) tile and pantile (S-shaped or curved) roofs were capped at the ridge with semicircular ridge tiles. Clay roofing tiles on buildings in mid-18th century Moravian settlements in Pennsylvania closely resembled those used in Germany at the time. These tiles were well-nigh 14"-15" long x 6"-7" wide (36cm-38cm ten 15cm-18cm) with a curved barrel, and with vertical grooves to assistance drainage. They were also designed with a lug or nib on the back then that the tiles could hang on lath without nails or pegs.
The accurate dating of early roofing tiles is difficult and often impossible. Fragments of tile found at archeological sites may indicate the being of dirt tile roofs, but the same type of tile was besides sometimes used for other purposes such as paving, and in broil ovens. To further complicate dating, since clay tile oftentimes outlasted many of the earliest, less permanent structures, information technology was frequently reused on subsequently buildings.
Asphalt shingles are an incompatible replacement substitute for the original Spanish dirt tiles. Photograph: NPS files.
Clay Tile Substitutes render to top ▲
In add-on to canvass metal "tile" roofs introduced in the middle of the 19th century, concrete roofing tile was developed as some other substitute for clay tile in the latter role of the 19th century. It became quite popular by the beginning of the 20th century. Concrete tile is composed of a dense mixture of portland cement blended with aggregates, including sand, and pigment, and extruded from high-pressure level machines.
Although information technology tends to lack the color permanence and the subtle color variations inherent in natural dirt tile, concrete tile continues to be a popular covering fabric today because it reproduces the general look of clay tile, if not e'er the verbal profile or proportions of historic clay tile, at a somewhat lower cost and weight. Another modern, slightly cheaper and lighter substitute for clay tile more than recently adult consists of a mixture of mineral cobweb and cement with pigments added to supply color. While these amass tiles besides replicate the shape and appearance of clay roofing tiles, they have many of the aforementioned dissimilarities to dirt tiles that are found in concrete tiles. Thus, like concrete tiles, they are seldom appropriate substitutes for clay tiles.
Traditional Tile Shapes and Colors return to pinnacle ▲
There are two types of clay roofing tiles: interlocking and overlapping. Interlocking tiles are designed in pairs and then that an extrusion or "lip" on one of the tiles "hooks" over the other tile thereby "locking" or securing the two together; they are also usually nailed to the roof construction. Overlapping tiles, which can also function in pairs, generally do not accept whatever sort of "lip" and must exist nailed in place. There is a broad range of shapes of historic clay roofing tiles, and many, sometimes with slight variations, are still produced today. There are many variations, and the country of origin of some of them may exist revealed in their names, but there are essentially merely two kinds of shapes: pantiles and flat tiles. Both pantiles and apartment tiles may be either interlocking or overlapping.
Pantiles
The shape near commonly associated with historic dirt roofing tiles is probably that of convex or rounded tiles, oft grouped together generically as "pan tiles" or "pantiles." These include Castilian tiles-sometimes chosen "South" tiles, or the similarly shaped Mission tiles, also known as Barrel or Barrel Mission tiles, straight or tapered, every bit well as Roman tiles, and their Greek variation.
Flat Tiles
Flat, shingle tiles are another type of historic clay roofing tiles. Apartment tiles can be completely plain and apartment, and, like roofing slates, overlap one some other, attached with nails to the roof capsule. Or they may interlock at the pinnacle and on one side. Although the "interlock" holds them together, almost interlocking shingle tiles also take one or more holes, commonly well-nigh the top, for nailing to the roof sheathing. Flat tiles are generally variations of English or Shingle tiles, and include English Shingle, Closed Shingle, Flat, Shingle or Slab Shingle, as well as French tiles which take a slightly college and more than contoured contour.
Any of the standard tile shapes may be known by a unlike proper name in another region of the country, or in different parts of the earth. For case, what are known equally Spanish or "Southward" tiles in the United States, may exist called Single Roman tiles in England. Sometimes Spanish and Mission tiles are equated despite the fact that the one-time are commonly 1-slice interlocking tiles and the latter are single Ω cylinders that overlap. Since missions and the Mission mode are associated with the Americas, Mission tiles in the United States are more commonly referred to as Spanish tiles in England and Europe. In a similar vein, Castilian or "S" tiles, or Butt tiles, might seem to be more than typical of some tiles used in France than what are marketed as French tiles by American manufacturers.
Today some tile manufacturers have given their ain trademark name to historic tile shapes. Other companies market uniquely shaped "S" tiles that are more in the shape of a true, but rather low contour "southward" without the customary flat portion of traditional American "S" tiles.
An eave closure or birdstop to keep out birds is notably absent from the replacement tile in the center of the bottom row. Photo: NPS files.
Field and Specialty Tile
The tiles that cover the majority of the flat surface of the roof are chosen 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 end tiles to complete the roof covering parcel. Other uniquely-shaped tiles were made to fit odd-shaped spaces and places including dormers and valleys, roof hips, rakes, ridges and corners. In that location are besides finish tiles that fulfill sure needs, such every bit eave closures or clay plugs called "birdstops." These are intended to keep out snow and rain, and birds from nesting in the voids nether the bottom row of curved tiles. Dissimilar patterns and designs can also be created by combining, or mixing and matching flat tiles with dimensional tiles.
Tile Colors
A terra cotta red is the color most commonly associated with historic dirt roofing tiles. The reddish color comes from clay with a big percentage of fe oxide, and there are many variations of this natural color to be found in tiles ranging from deep reddish browns to softer and paler oranges and pinks. Lighter vitrify and beige colors, besides as black, too appear on traditional tile-roofed buildings. Buff-colored tiles were made from nearly pure fire clay, and pouring manganese dissolved in h2o over the tile before firing resulted in smoke brownish or black glazed tiles. Toward the cease of the 19th century the popularity of colored glazes for roofing tiles increased, and their use and the range of colors continues to expand today. Well-nigh historic glazed roofing tiles are in fairly natural hues that range from reds and browns and buffs, to blacks and purples, dejection (often created with smalt, or powdered blue glass), and a wide variety of greens (ordinarily created with copper slag). There could be a considerable range in the colors of tiles that were baked over a forest burn considering the temperature inside the kiln was so uneven; tiles closest to the fire cooked all the way through and turned a darker red, while tiles uttermost from the flames were probable to be fume-stained, and lighter orange in color.
How Tiles are Attached return to top ▲
The method used to attach clay roofing tiles varies according to the shape, size and way of the particular tile. For the most part, traditional and modernistic methods of installing dirt roofing tiles are very similar, except that modern do e'er includes the use of woods sheathing and roofing felt. But almost of the earliest clay covering tiles were laid without do good of wood capsule 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 enough of ventilation, and made it easy to find leaks and make repairs, information technology also meant that the overall water-tightness of the roof depended entirely on the tiles themselves.
Projections on the underside of these replacement Castilian clay tiles help them adhere to the cement mortar on the roof capsule. Photograph: NPS files.
Gradually, the do evolved of nailing covering tiles directly onto continuous forest sheathing, or hanging them from "nibs" on horizontal lath that was attached to roof rafters or sheathing. Some kinds of tile, peculiarly the subsequently Mission or Barrel tiles were laid over vertical strips or battens nailed to the capsule, or the tiles were fastened to woods purlins with copper wire.
Partly because they do not always fit together very closely, some tile shapes, including Spanish, Barrel or Mission equally well as other types of interlocking tiles, are non themselves completely water-repellent when used on very low-pitched roofs. These take always required some form of sub-roofing, or an additional waterproof underlayer, such as felting, a bituminous or a cementitious blanket. In some traditional English applications, a treatment called "torching," involved using a simple kind of mortar most unremarkably consisting of straw, mud, and moss. The tapered Mission tiles of the old Spanish missions in California were besides laid in a bed of mud mortar mixed with grass or straw which was their only means of attachment to the very low-pitched reed or twig sheathing (latia) that supported the tiles.
More recent and contemporary covering practices crave that the tiles be laid on solid l" (two.5cm) wood sheathing felted with coated base of operations sheets of at to the lowest degree 30 lbs., or built-upward membranes or single-ply roof membranes. This essentially increases the water-tightness of the roof by adding a second layer of waterproofing. Horizontal and vertical chalk lines are fatigued to serve as a guide in laying the tile and to indicate its patterning. Most tiles are designed with one or two holes so they tin can be fastened past copper nails or hangers, and/or with projecting nibs, to interlock or hang on battens or lath fastened to the base capsule.
Before laying the tiles, the copper or lead gutters, flashings and valleys must be installed, preferably using at least #26 judge (20-24 ounce) corrosion-resistant metallic extending a minimum of 12" (30.5cm) under the tile from the edge, or in accord with the manufacturer'due south specifications. The long life and expected durability of dirt tiles require that, equally with the roofing nails, only the best quality metal be selected for the flashing and guttering.
These tapered barrel dirt tiles were accurately reproduced from archeological materials found on site. Photo: NPS files.
"Field tile" is usually ordered by the number of "squares"-that is, a flat section x' x 10' (25cm x 25cm)—needed to cover a roof section. The tile company or covering contractor should calculate the number of tiles needed according to the blazon of roof, and based on architect'south drawings to ensure accuracy. This should include specialty ridge and eave tiles, decorative trim, partial "squares" approximately 10-xx per cent assart for breakage, and extra tiles to store for repairing incidental impairment later. Once at the site, the tile is evenly distributed in piles on the roof, inside piece of cake achieve for the roofers.
The tiles are laid first with the first class at the lower edge of the roof at the eaves. The method by which roofing tiles are laid and attached varies, depending on the type and design of the tiles and roof shape, too every bit on regional practice and local weather condition atmospheric condition. A raised fascia, a deceit strip, a double or triple layer of tiles, or special "birdstop" tiles for nether the eaves, may exist used to raise the first row of tiles to the requisite meridian and bending necessary for the all-time operation of the roof. The tile is positioned to overhang the previously installed gutter system by at least i-1/2" (4cm) to ensure that rainwater discharges into the key portion of the gutter. One time this first course is carefully fitted and examined from the ground level for straightness and color nuances, and adjusted accordingly, successive courses are lapped over the ones below as the roofer works diagonally up the roof toward the ridge. Positioning and laying tiles in a 10" 10 10" (25cm x 25cm) square may take on the boilerplate of sixteen-1/ii man hours.
Flat Tiles render to top ▲
Well-nigh flat clay tiles have ane or ii holes located at the height, or on a "nib" or "lug" that projects vertically either from the confront or the underside of the tiles, for nailing the tile to the sheathing, battens, or furring strips beneath. As successive rows of tile are installed these holes will be covered by the next course of tiles above. Traditionally, clay tiles on the oldest tile roofs were hung on roofing laths with oak wooden pegs. As these forest pegs rotted, they were normally replaced with nails. Today, copper nails, 1-three/4" (4.5cm) slaters' nails, are preferred for attaching the tiles because they are the longest lasting, although other corrosion-resistant nails tin can likewise be used. Less durable nails reduce the longevity of a clay tile roof which depends on the fastening agents and the other covering components, every bit much as on the tiles themselves. Clay roofing tiles, similar covering slates, are intended to hang on the nails, and nailheads should always be left to beetle slightly higher up the surface of the tile: Nails should non be driven too deeply into the furring strips because too much pressure on the tile can cause it to interruption during freeze/thaw cycles, or when someone walks on the roof.
Plain flat tiles, like covering slates, are attached to the roof sheathing simply with nails. They are laid in a pattern overlapping one some other in order to provide the caste of impermeability necessary for the roof covering. Considering plain flat tiles overlap in most cases nearly every bit much of i half of the tile, this type of tile roof roofing results in a considerably heavier roof than does an interlocking tile roof which does not require that the tiles overlap to such an extent. Interlocking flat tiles form a single layer, and an unbroken roof covering. Although most interlocking tiles on all but the steepest roofs can technically be expected to remain in place because they hang on protruding nibs from the roofing laths or battens, in contemporary roofing practices they are often likely to be nailed for added security. In nigh cases it is usually a good idea to boom at least every other tile.
Pantiles render to top ▲
With Mission or Barrel tiles, where one half-cylinder overlaps some other inverted half-cylinder to class a cover and pan (cap and trough) arrangement, the fastening is more than complicated. While the pantiles that rest direct on the capsule are simply nailed in place, in that location are ii ways of attaching the cover tiles that rest on the pantiles. They tin can be secured past a copper wire nailed to the sheathing or tied to vertical copper strips running behind the tiles. Another method requires the installation of vertical battens or nailing strips on the roof to which the encompass tiles are nailed, or the use of tile nails or hooks, which are hooked to the pantile below and secured with twisted copper wire.
Sometimes cement mortar, or some other underlayer such as grass, moss or straw, or hair-reinforced mortar was added under the tiles. Earlier the use of felting this was a especially mutual do on some of the patently flat tile or Spanish tile roofs with low rises that were themselves not especially waterproof. Mortar likewise helped to keep driving rain from getting under the pantiles, and it is nevertheless customary in contemporary roofing to add a dab of cement mortar to help secure them.
Ridge or Hip Tiles return to summit ▲
At the roof ridge or hip, clay tile is usually attached to a raised stringer with nails and a small corporeality of mortar, elastic cement or mastic. The joint is sealed with a flexible flashing such as copper or lead. Ridge tiles are ofttimes somewhat larger and more than decorative than the field tile utilized on the broad sections of the roof.
Roof Pitch and Weather condition Factors in Tile Attachment render to top ▲
The means by which clay tile is attached to the capsule is too partly adamant by the roof pitch. Generally the fastening requirements increment with an increase of roof pitch. For low-pitched rises of 4"-6" (10cm-15cm) in a 12" (xxx.5cm) run the weight of the tiles is usually sufficient to hold them in place on the board by the ridge or "lug" on the underside of the tile, with only the perimeter tiles requiring metal clips to secure them to the sheathing. But the tiles on even these low-pitched roofs are usually nailed for added security, and additional fastening measures are necessary on roofs with a college pitch, or in areas subject to high winds or earthquakes. For steeper pitched roofs, such as towers, seven"-11" (18cm-28cm), or 12"-15" (30.5cm-38cm) in a 12" (xxx.5cm) run the tiles are nailed and a ring of perimeter tiles three to four tiles thick is secured with clips. For roof rises over sixteen" (41cm) in a 12" (30.5cm) run, and in areas decumbent to earthquakes or hurricanes, every tile may exist secured with both a nail and a copper or noncorrosive metal prune, and often also with a dab of roofing mastic or mortar.
The installation of clay roofing tiles in areas with significant amounts of snowfall-over 24" (61cm) per year-too varies somewhat from the normal guidelines. Larger battens may exist necessary, likewise as additional clipping or tying of the tile to securely attach it to the sheathing. The roof structure itself may also need added bracing, as well as the insertion of small snow clips or snow birds that protrude above the surface of the tile to forbid snow and ice from sliding off the roof and dissentious the tile.
Preservation and Repair return to top ▲
Identifying Common Problems and Failures
While clay roofing tiles themselves are most likely to deteriorate considering of frost damage, a clay tile roof organization most commonly fails due to the breakup of the fastening system. As the wooden pegs that fastened the early on tiles to manus-riven battens rotted, they were often replaced with iron nails which are themselves hands corroded by tannic acrid from oak battens or sheathing. The deterioration of metal flashing, valleys, and gutters can likewise atomic number 82 to the failure of a dirt tile roof.
Another area of potential failure of a historic clay tile roof is the back up arrangement. Clay tiles are heavy and it is important that the roof structure exist audio. If gutters and downspouts are allowed to fill with droppings, water can support and seep nether roofing tiles, causing the eventual deterioration of roofing battens, the sheathing and fastening arrangement, or even the roof'due south structural members. During freezing conditions, water ice can build up under tiles and cause breakage during the freeze/thaw cycle. Thus, as with whatsoever type of roof, water and improperly maintained rainwater removal and drainage systems are also principal causes for the failure of historic clay tile roofs.
Dirt tiles may be either handcrafted or automobile-made; in general, roofs installed before the finish of the 19th century consist of paw formed tiles, with car-fabricated tiles condign more dominant as technology improved during the 20th century. Clay tile itself, whether made by manus or made past car, can vary in quality from tile to tile. Efflorescence of soluble salts on the surface may point that a tile has excessive porosity which results from nether-burning during its manufacture. Poor quality porous tiles are peculiarly susceptible to breaking and exterior surface spalling during freeze-thaw cycles. By letting in wet, porous tiles can let the roof battens and roof construction to rot. The trouble may be compounded by waterproof building paper or building felt laid underneath which tin can, in some instances, forestall acceptable ventilation.
Dirt covering tiles can also be damaged by roofers walking carelessly on an unprotected roof while making repairs, or past overhanging tree branches, falling tree limbs, or heavy hail. Broken tiles may no longer provide a continuous waterproof surface, thereby allowing h2o to penetrate the roofing structure, and may eventually issue in its deterioration if the broken tiles are non replaced in a timely manner.
Although modern, machine-fabricated clay tiles are more than uniform in advent than their handmade counterparts, they also have the potential for failure. Occasionally, entire batches of mass-produced tile can be defective.
Regular Inspection and Maintenance
A special system consisting of contumely or copper wires is used to adhere these tapered butt roof tiles. Photo: NPS files.
Broken or missing tiles, or leaks on the interior of the building, are obvious clues that a celebrated clay tile roof needs repair. Fifty-fifty though it may exist clear that the roof is leaking, finding the source of the leak may not be so piece of cake. Information technology may require thorough investigation in the attic, besides as going upward on the roof and removing tiles selectively in the approximate surface area of the roof leak. The source of the leak may not really be located where information technology appears to be. Water may come in 1 place and travel along a covering member some distance from the actual leak before revealing itself past a water stain, plaster damage, or rotted wooden structural members.
Temporary Protection during Repair
In some instances temporary protection and stabilization may be necessary to forestall further damage or deterioration of a historic clay tile roof. Plywood sheets, plastic, roll roofing, or roofing felt tin can provide short-term protection until repair or replacement materials can be purchased. Another option may be to erect a temporary scaffold that is encased or covered with clear or semitransparent polyethylene sheeting over the entire roof. This will non only protect the exposed roofing members during repair or until repairs tin exist fabricated, but also lets in enough natural lite to enable the reroofing piece of work to take place while sheltering workmen from common cold or wet weather condition.
General Repair Guidance
Once the source and cause of a leak has been identified, appropriate repairs must be made to structural roofing members, wood sheathing, felt or roofing newspaper if information technology is part of the covering membrane, or possibly to vertical roof battens to which the tiles may exist attached. If the trouble appears limited to gutters and flashing in busted, repair or replacement will probably require temporary removal of some of the adjacent tiles to gain access to them. If the covering tiles are extremely frail and cannot be walked on even with adequate protection (run into beneath), information technology may also be necessary to remove several rows or a larger expanse of tiles and shop them for later reinstallation in order to create a "path" to reach the area of repair without damaging existing tiles. Even if most of the tiles themselves appear to be intact merely no longer deeply attached to the roof substrate due to deterioration of the fastening system or covering members, all the tiles should be labeled and removed for storage. Regardless of whether the repair project involves removal of only a few damaged tiles, or if all the tiles must be removed and relaid, historic clay covering tiles are inherently fragile and should be pulled up advisedly with the use of a slate ripper. The tiles tin can exist reattached one-by-1 with new corrosion-resistant copper nails, copper straps or tabs, "tingles', or some other ways afterward the necessary repairs have been made to the roof.
Replacing Individual Tiles
The nigh difficult attribute of replacing a single broken clay roof tile is doing so without breaking neighboring tiles. While apartment shingle tiles can generally be walked on by a conscientious roofer without likelihood of much damage, high profile pantiles are very fragile and easily broken. Past using sheets of plywood, planks, or burlap numberless filled with sand to distribute weight, the professional person roofer can move virtually the roof to fix cleaved tiles or flashing without causing boosted damage. Some other method involves hooking a ladder on the ridge to support and evenly distribute the weight of the roofer.
A broken tile should be carefully removed with a slate ripper or hacksaw bract inserted under the tile to cut the nail or nails holding it in place. If successive layers of tile are already in place covering the nailholes, it will not be possible to attach the replacement tile with nails through the holes, so an alternative method of zipper will be necessary. By nailing a tab of double thickness copper stripping on the capsule below the tile, the new replacement tile can exist slipped into position and secured in identify by angle the copper strip upwards with a double thickness of the copper over the tile. A slate hook or "tingle" can be used in the same style. This fastening system functions in place of nails.
When replacing hard-to-match celebrated tile, and if matching dirt tile cannot be obtained, it may be possible to relocate some of the original tiles to the more than prominent locations on the roof where the tile is damaged, and insert the new replacement tile in secondary or rear locations, or other areas where it will non evidence, such as behind chimney stacks, parapets, and dormer windows. Even though replacement tile may initially friction match the original historic tile when start installed, it is likely to weather or age to a somewhat different colour or hue which volition become more obvious with time. Thus, care should be taken to insert new replacement tile in equally inconspicuous a location equally possible. New, car-made clay tile or concrete tiles should generally not exist used to patch roofs of onetime, handmade tile considering of obvious differences in advent.
Sources for Replacement Tiles
When restoring or repairing a dirt tile roof it is always recommended that as many of the original tiles be retained and reused as possible. Sometimes, particularly when working with "pan and embrace" type tile roofs, while many of the "cover" tiles may be cleaved and require replacement, information technology may be possible to reuse all or most of the "pan" tiles which are less susceptible to impairment than the "cover" tiles. But, in most cases, unless matching replacements can be obtained, if more than about thirty per cent of the roofing tiles are lost, broken, or irreparably damaged, information technology may be necessary to replace all of the historic tiles with new matching tiles. When counting the number or percentage of missing or cleaved tiles that need to exist replaced, information technology is important to social club extra tiles to allow for breakage and damage during aircraft and on the job site. The size of the tiles must be noted, whether they are withal size, the aforementioned size only laid with dissimilar amounts of exposure to compensate for changes in perspective, or of graduated sizes co-ordinate to horizontal rows-typical, for case, on conical or tower roofs.
Many late-19th and early-20th century tiles are marked on the back with the proper name of the company that made them, forth with the size and the name of that particular tile shape. Some companies that were in concern in the Usa at the turn of the century are however producing many of the traditional tile shapes, and may be able to supply the necessary replacements. But information technology is important to be aware that in some cases, although the proper name of a detail tile pattern may take remained the same, the actual shape, size, thickness and contour may accept inverse slightly so that the new tile does not match the historic tile closely enough to let it to serve as a uniform replacement for missing or cleaved tiles. While such tiles may be acceptable to use on a secondary or less prominent height, or to use when an entire tile roof needs replacement, they would not be suitable to utilise on an area of the roof that is highly visible.
Even if the particular tile is no longer manufactured past a company, the original molds may still exist which can exist used to make new tiles to lucifer the historic tiles if the quantity needed is sufficiently big to warrant a custom order. Other companies stock and sell salvaged tile, and keep a variety of former tiles bachelor which tin be identified and matched past the number and visitor imprint on the back of the tiles. Still other companies specialize entirely in custom-made reproduction of historic clay tiles for a specific preservation project.
Modern clay tiles are even more varied than historic tiles. Many shapes and styles are offered in a broad variety of colors and glazes. Several manufacturers produce special color-blended tiles, every bit well equally tiles of dissimilar hues that are intended to exist advisedly mixed when installed. Yet, it is important to remember that many of these modern tiles may non be appropriate for use on historic clay tile roofs. The identify of manufacture must also be taken into consideration. For example, tiles fabricated for use in a hot, dry climate may not be able to withstand moisture conditions, drastic temperature changes or freeze-thaw cycles. Some of the tile shapes, and many of the colors-especially those that are very bright and highly glazed-are completely contemporary in design, and do non represent traditional American styles, and thus, are non suitable for use on historic buildings.
Repairing a Failed Fastening Arrangement
Clay roofing tiles, as noted earlier, oftentimes outlive their fastening systems. Wood pegs rot, nails rust, and even copper nails that are not fairly driven in can pull out of the roof's structural members. Although it is unusual that all of the clay tiles on a roof demand to exist replaced unless matching replacements cannot be obtained, information technology is not uncommon for old tile roofs to be stripped of all their tiles in order to relay the tiles with new fastenings and battens. When the fastening organisation has failed, all the roof tiles must exist removed and reattached with new corrosion-resistant fasteners. If possible, all the tiles should be numbered and a diagram should exist drawn showing the location of each tile to aid in replicating the original pattern and color variations when the tiles are relaid. Ideally, each tile should exist numbered to ensure that it is reinstalled in its original location. But this may non always exist feasible or practical, and it may be enough merely to group the tiles equally they are removed by type and size or function-such as field tiles, custom tiles for hips, dormers and ridges, and particularly cutting pieces. This will help facilitate reinstallation of the tiles. If all of the tiles have to be removed, it is probably a good idea to consider installing a layer of modern roofing felt over the wood sheathing. This will add together another layer of waterproofing, while providing temporary protection during reroofing.
Even if the tiles were originally attached with wooden pegs, information technology is generally recommended that they be rehung with corrosion-resistant, preferably heavy copper, or aluminum alloy nails or hooks. Today there are numerous nontraditional fastening systems for clay tile roofs, and many of them are patented. Roofing contractors and architects may have private preferences, and some systems may be better suited than others to fit a particular roof shape or to encounter a specific climatic or seismic requirement. Original battens or other roof members that may have deteriorated should exist replaced to match the original using pressure-treated forest. Boosted back up may exist necessary, particularly if the original roof was inadequate or poorly designed.
Replacing Flashing
Deteriorated flashing, gutters and downspouts should generally be replaced in kind to match the historic material. Copper or lead-coated copper, if appropriate to the building, or terne-coated stainless steel, is often preferred for employ on historic dirt tile roofs considering of their durability and long lasting qualities. Withal, copper staining from downspouts tin can sometimes exist a problem on light-colored masonry walls which should be taken into consideration when planning replacements to rainwater removal systems. Clay tile roofs commonly have an open valley system where the tiles are separated by metal flashing at intersections of roof sections with dissimilar angles. This makes the insertion of new flashing quite easy, as only a few surrounding tiles must be removed in the process. New copper flashing that is likewise "bright" can be made to blend in and "mellowed" past brush-coating information technology with boiled linseed oil or proprietary solutions.
Inappropriate Repairs
The most important repair to avoid is replacing cleaved or missing roof tiles on a historic building with materials other than matching natural clay tiles. Concrete, metal or plastic tiles are mostly not appropriate substitutes for clay roofing tiles. They lack the natural color variations of dirt tile, and they practise non take the same texture, shape, thickness or surface irregularities.
Although much concrete tile and composition tile is produced to resemble the general shape, if not the verbal contour, of dirt roofing tiles, concrete tile is generally too thick and also lacks the range of colors inherent in natural dirt tile. Concrete tile is not a uniform substitute textile to repair or supplant individual celebrated dirt tiles.
Patching a historic clay tile roof with roofing tar, caulk, cobblestone, pieces of metal, or non-matching clay tiles is also inappropriate. Such treatments are visually incompatible. They besides have the potential for causing physical impairment. Water can collect behind these patches, thus accelerating deterioration of roof sheathing and fastening systems, and during the expansion and contraction of a freeze-thaw bicycle ice buildup at patches tin can interruption surrounding tiles.
Summary and References return to top ▲
Clay roofing tile itself, when correctly installed, requires niggling or no maintenance. Frequently, information technology is the fastening system used to secure the tiles to the capsule that fails and needs to be replaced rather than the tiles themselves. In fact, because clay tiles oft outlasted the building structure, information technology was not unusual for them to be reused on another building. When the fastening system has deteriorated, or the roofing back up structure has failed, dirt tiles can be removed relatively easily, necessary repairs can be made, and the historic tiles can exist relaid with new corrosion-resistant nails or hooks. Cleaved or damaged tiles should be replaced promptly to prevent further damage to neighboring tiles or to the roof structure itself.
As with whatever kind of celebrated roofing material, regular maintenance, such as cleaning gutters and downspouts, tin add to the life of a tile roof. Additional preventive measures may include placing wire mesh over downspout openings or over the entire gutter to foreclose debris from collecting and water from backing upwards. Periodic inspection of the underside of the roof from the attic later on a heavy pelting or ice tempest for h2o stains may reveal leaks in their early on stages which tin exist eliminated before they escalate into larger, more than serious repair problems.
If replacement tile is required for the project, it should match the original tile equally closely as possible, since a historic clay tile roof is probable to be one of the edifice's about significant features. Natural clay tiles accept the inherent color variations, texture and color that is and so important in defining the graphic symbol of a celebrated tile roof. Thus, only traditionally shaped, dirt tiles are appropriate for repairing a historic clay tile roof.
Selected Sources of Clay Roofing Tiles
Boston Valley Terra Cotta
6860 S Abbott Road
Orchard Park, NY 14127
Custom-fabricated architectural terra cotta and clay roofing tiles
C.C.N. Clay Roof Tiles (Canteras Cerro Negro S.A.)
8280 College Parkway, Suite 204
Ft. Myers, FL 33919
Distributors of C.C.Due north. clay roofing tiles from Argentina
World/Forms of Alfred
5704 East Valley Road
Alfred Station, NY 14803
Made-to-order reproduction clay roofing tiles
Gladding, McBean and Co.
P.O. Box 97
Lincoln, CA 95648
Manufacturer since 1875 of terra cotta and dirt covering tiles, and custom reproductions
Hans Sumpf Company, Inc.
40101 Avenue 10
Madera, CA 93638
Fabricated-TO-Guild Mission-fashion dirt roofing tiles
International Roofing Products, Inc.
4929 Wilshire Blvd., Suite 750
Los Angeles, CA 90010
New clay roofing tiles, some suitable for celebrated buildings
London Tile Co.
65 Walnut Street
New London, OH 44851
Fabricated-TO-ORDER reproduction clay covering tiles
LudowiciCeladon, Inc.
4757 Tile Constitute Road
New Lexington, OH 43764
Manufacturer since 1880s of clay roofing tiles, and custom reproductions
Grand.C.A. (Maruhachi Ceramics of America, Inc.)
1985 Sampson Avenue
Corona, CA 91719
New dirt roofing tiles, some suitable for historic buildings
The Northern Roof Tile Sales Visitor
P.O. Box 275
Millgrove, Ontario LOR 1VO, Canada
Traditional clay roofing tiles imported from England and South America
Raleigh, Inc.
6506 Business U.Southward. Road xx
P.O. Box 448
Belvidere, IL 61008-0448
Inventory of new and salvage clay roofing tiles
Supradur Manufacturing Corp.
P.O. Box 908
Rye, NY 10580
Imports Spanish ("S") dirt roofing tiles from France
TileSearch
P.O. Box 580
Roanoke, TX 76262
Computerized network for new and save clay roofing tiles
U.s.a. Tile Visitor
P.O. Box 1509
909 West Railroad Street
Corona, CA 91718
New clay roofing tiles, some suitable for historic buildings
Notation: Measurements in this publication are given in both the U.S. Customary System and International (Metric) System for comparative purposes. Metric conversions are, in some cases, approximate and should not exist relied upon for preparing technical specifications.
Acknowledgements
Anne East. Grimmer is a senior Architectural Historian with the Preservation Assistance Partition of the National Park Service; Paul G. Williams is a Cultural Resource Manager with the Air Force. Both authors wish to thank the following individuals for the technical assist they provided in the preparation of this publication: Edna Kimbro, Architectural Conservator, Watsonville, CA; Edwin Due south. Krebs, AIA, G. Norman Berry Associates, Louisville, KY; Melvin Mann, TileSearch, Roanoke, TX; Walter Due south. Marder, AIA, Division of Historical Resources, Tallahassee, FL; Gil S·nchez, FAIA, Gilbert Arnold Southward·nchez, Incorporated, Santa Cruz, CA; Terry Palmiter and Sandra Scofield, Alfred, NY; and National Park Service professional person staff members. In improver, the authors wish to thank Karin Murr Link, who produced the drawings which illustrate this Brief.
This publication has been prepared pursuant to the National Historic Preservation Human activity of 1966, as amended, which directs the Secretary of the Interior to develop and make available information concerning celebrated properties. Technical Preservation Services (TPS), National Park Service prepares standards, guidelines, and other educational materials on responsible historic preservation treatments for a broad public.
September 1992
Reading List render to tiptop ▲
Azevedo, J. "Tile Roofing." Fine Homebuilding. No. threescore (April/May 1990), pp. 3641.
Belle, John, John Ray Hoke, Jr., and Stephen A. Kliment, editors. Traditional Details for Building Restoration, Renovation, and Rehabilitation. From the 19321951 Editions of [Ramsey/Sleeper] Architectural Graphic Standards." New York: John Wiley & Sons, Inc. 1991.
Davis, Charles Thomas. A Applied Treatise on The Manufacture of Brick, Tiles, Terracotta, Etc. Philadelphia: Henry Carey Baird & Co., 1884.
Fidler, John. "Tile, Slate and Stone Roofs." Traditional Homes Technical Information Leaflet. Number i. 1991.
Labine, Clem. "How to Repair an Onetime Roof" The Old-House Journal. Vol. XI, No. 3 (April 1983), pp. 6469
Labine, Clem, and Judith Siegel Lief. "The Ascension of the Ornamental Roof,' and "Traditional Building'south Source-List of Traditional Roofing & Specialties." Traditional Edifice. Vol. 5, No. three (May/June 1992), pp. 3546.
Melville, Ian A., and Ian A. Gordon. The Repair and Maintenance of Houses. London: The Estates Gazette Express, 1973.
Poore, Patricia. "Tile Roofs." The Old-House Journal. Vol. XV, No. 5 (September/October 1987), pp. 2229.
"Special Roof Issue." The Old-Firm Periodical. Vol XI, No. 3 (April 1983).
Sweetser, Sarah M. Preservation Briefs 4: Roofing for Celebrated Buildings. Washington, D.C.: National Park Service, U.Due south. Department of the Interior, 1978.
Vogel, Neal A. Covering Houses of Worship: Roofing Guidance for Church and Temple Administrators. Information Serial No. 59. Chicago: National Trust for Celebrated Preservation and Inspired Partnerships, 1992.
White, Richard. Olmsted Park System, Jamaica Plain Boathouse, Jamaica Plain, Massachusetts: Planning for Preservation of the Boathouse Roof. Preservation Case Studies. Washington, D.C.: Heritage Conservation and Recreation Service, U.S. Department of the Interior, 1979.
Source: https://www.nps.gov/tps/how-to-preserve/briefs/30-clay-tile-roofs.htm
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