John A. D’Annunzio
Tile roof application is prominent in residential construction in the Southeast and Southwest regions of the United States. Tiles provide significant advantages on steep-slope applications. They provide distinctive architectural aesthetics because of their color, texture and the play of light and shadow. They are naturally fire-resistant. Other distinct advantages include durability and longevity. They are able to withstand harsh environments and, when properly maintained, could provide 50 to 100 years of service life.
Recent studies indicate concrete and clay tiles have energy-efficient properties that can help reduce energy costs. It has long been recognized that light-colored tiles provide reduce the amount of heat transferred through the roof to the interior of the structure. Recent research conducted by Oak Ridge National Laboratory indicates further energy savings is provided by the tile’s mass, reflectivity and ventilation beneath the tiles. These attributes in both clay and concrete tiles reduce heat transference by 50 compared to conventional shingles.
A disadvantage of tile roofs is that their initial application costs are relatively high due to material costs and the labor-intensive application process. Tiles are applied through mechanical anchoring or set in foam or mortar. Tile roofs can be cost-effective if the initial costs are amortized over the life of the system. Proper maintenance and repair can extend the service life of tiles, providing a long service life that helps justify the high initial costs.
Most roof tiles are manufactured using high-quality concrete and clay components. This makes the products very durable and allows them to withstand harsh elements such as wind, rain, snow and ice. Failure to tiles created by weather events can be repaired if the damage is in isolated areas. If more than 25 percent of the total roof area is damaged, full roof replacement may be required by code or economic parameters. Tiles typically do not wear out; most roof leaks are caused by failure of metal flashings or failure of mechanical fasteners.
Tile Repair Methods
Broken, cracked and missing tiles should be removed and replaced. Tiles surrounding the damaged tiles should be carefully lifted and replaced in conjunction with the new tiles. Surrounding tiles can be inspected for damage by gently tapping on the tile to determine if it has maintained its structural integrity or if it has hidden fissures that require repair. The tile head lap should be a minimum of 3 inches. The noses of all tiles shall be fastened. The noses of all eave course tiles shall be fastened with clips or other attachment methods that are approved by the local code requirements.To keep the interior of the facility dry in case of tile damage, an underlayment system is required over the deck. On slopes of less than 3:12, a minimum three-ply BUR felt is required. On slopes of 3:12 or more, an underlayment is required with 6-inch side laps and a 2-inch headlap. Two underlayments are typically required in high-velocity wind regions. A 30-pound felt is fastened to the deck and a 90-pound felt is adhered (in hot asphalt or cold adhesive) over the underlayment. Fastening of the underlayment to the deck should be in accordance with the wind uplift engineering calculations that are completed for the project.
The International Building Code (IBC) stipulates that metal used for valleys, wall trays, roof-to-wall flashings and pipe flashings should be a minimum of 26-gauge galvanized metal. If there are problems with metal flashing after installation, lifting a limited number of tiles in the adjacent area is necessary for replacement of the flashing. It is important the lifted tiles are carefully set back in place.
Tile displacement is typically created by missing mechanical fasteners or fasteners backing out. All loose and missing fasteners should be removed and replaced. Mechanical attachment should be in accordance with the tile manufacturer’s requirements and local codes. On roof slopes that are less than 3:12, one fastener per tile is required. On roof slopes of more than 3:12, two fasteners per tile are required. The fasteners used for tile securement must meet ASTM A641 Class 1 standards. Most experts recommend the use of copper or stainless steel nails with tiles due to the tendency of galvanized nails to rust. Similarly, any tile disbondment created at foam or mortar attachment locations should be lifted and properly secured with the appropriate material.
One of the challenges of repairing older tile, slate or even shingle roofs is trying to match the new repair materials with older, faded materials. Tiles have a tendency to discolor over time, particularly if they have been in place for decades. It may also be difficult to procure the exact tile size, shape and texture. In these conditions, the contractor may choose to remove good tiles from less-visible roof areas and replace them with the different tiles. This will provide a consistent aesthetic look throughout the visible roof area.
All openings at hips, ridges and head walls should be fitted with an approved weather-blocking material. Rake tiles shall be fastened with two nails. The nose of all ridges, hip and rake tiles shall be set in approved mastic.
