For our final blog post in our series about inspecting roof coverings, we look into the ins and outs of a roof type known for its distinctive style, resistance to heat and salt spray, and long service life—concrete and clay tiles. Though certainly not as popular as asphalt shingles, these materials can be found throughout the U.S., although they are most common protecting California and Florida homes.
Like other varieties of roof coverings we’ve discussed (asphalt, wood shakes and shingles, metal, and slate), tiled roofs—whether flat, S-type or barrel-shaped, overlapping or interlocking—have their own set of issues that may be highlighted during a comprehensive inspection.
A note about walking on tile roofs: Similar to slate and other roofing materials that are vulnerable to impact damage, setting foot on a tiled roof, especially clay, can cause damage. Rather than risking breaking tiles, your inspector may choose another method to evaluate the roofing system, such as viewing from a window, balcony, or ladder, or getting a closer look from the ground via binoculars or a drone.
Here’s a brief checklist of some of the problems the certified home inspectors at A-Pro Home Inspection have cited over the last 27 years when inspecting tile roofs. Let’s start with concrete.
Concrete Tiles Can Be Very Heavy: Weighing between 800 to 1,100 pounds per 100 square feet (modern, lighter-weight options are also available), concrete tiles can pose a serious threat to a home if proper support is inadequate. Water absorption can add additional heft to concrete tiles, increasing the potential for causing damage to the building. A common problem associated with heavy roofing material is the development of vertical and horizontal cracks in drywall or plaster. Different from diagonal cracks that are the result of foundational shifting, these compression cracks follow the seams of the drywall or plaster, throwing up a red flag to the inspector that the home’s framing may not be sufficient to support the concrete tile roof. Oftentimes, defects emerge when a concrete tile roof is chosen to replace a lighter-weight roof on a home not capable of handling the extra baggage.
Common Concrete Tile Observations: Broken, deteriorating, missing, and loose tiles will be observed and noted by the home inspector. There are a number of reasons tiles may be loose, including breakage and fastener issues (e.g., incorrectly installed, corroded, insufficient number, not long enough, wrong type). Cracking or splitting can be caused by moisture penetration, subsequent freezing, and expansion, which can lead to deterioration. When assessing the remaining life of the roof, the percentage of significantly damaged tiles will be a major factor in determining if the roof demands immediate replacement. Damage is common with interlocking tiles where narrower portions are most susceptible to wear. Further, broken tiles may be caused by falling tree branches or someone who has walked on the roof but not heeded recommended precautions for avoiding footfall damage to vulnerable parts of the tiles.
Clay Tile Damage: Clay tiles that have been made from substandard raw materials or those that have been subjected to less than ideal manufacturing processes may have higher levels of porosity, which will increase the likelihood of water absorption. When this water causes the tile to expand and contract through freezing and thawing, this can result in layers of the tile separating from each other and eventually flaking off (delamination) or surface deterioration (spalling). If deterioration is discovered on a few tiles, it is not uncommon for an inspector to find that the issue is widespread throughout the roof. This becomes a familiar issue when softer, low-vitrified clay tiles are used in freezing climates, where they are known to perform poorly.
Other Tile Problems: As with all roofs, proper flashing is critical on tiled roofs to prevent water intrusion. The inspection will include an examination to check for proper flashing methods best suited for the climate and particular tiled roof installed. Your inspector will report on the presence of efflorescence (dissolved salts found on the surface of porous materials), which indicates water absorption concerns and the possibility that the roof may be nearing the end of its useful life. In certain climates, both clay and concrete tiles are susceptible to algae and mold growth, which first appear between tiles as black or black-greenish streaks and stains, eventually covering the surface if neglected. These growths help to retain water and accelerate damage to tiles. Broken, cracked, or sliding tiles can expose a roof’s underlayment, which can lead to deterioration, roof leaks, and damage to the roof deck and the home’s structure.
Other common tile roof defects include damage to roof edges, soffit, and valleys—all of which will undergo careful examination by your home inspector. Clay tiles are even heavier than concrete, weighing as much as 1,500 pounds per 100 square feet, so your inspector will be checking internal walls for cracks. Amateurish repairs of roofing tiles may also end up in the final home inspection report.
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