Clay roof tiles have been utilized for centuries, and there is a reason for that. They are durable, fire-resistant, and can last decades, even generations, when they are properly manufactured and installed. But not all clay roof tiles are rated equally. If you have ever heard of terms such as Grade 1, 2, or 3, you might have wondered what these terms mean exactly.
The short answer — the grade of clay roof tiles is indicative of their level of weather resistance, and in particular, how well they stand up to moisture, freeze-thaw cycles, and structural stress over time.
Understanding those differences helps homeowners, builders, and architects select the right tile for the climate and performance requirements of a project. It’s not about one grade being universally “better.” It’s about the right performance characteristics of the tile to match the environment where the tile is to be installed. Although it’s true that Grade 1 offers the highest level of weather resistance under ASTM standards, the appropriate grade depends on the climate where the tile will be installed.
Verea Clay Tile manufactures all three grades to meet different needs, climates, and design objectives. Each grade has distinct strengths, and each plays an important role in roofing systems across different regions.
Why Clay Roof Tiles Last So Long in the First Place
Why Clay Roof Tiles Last So Long in the First PlaceBefore making a comparison between different grades, it is useful to know why clay roofing is so good.
Clay tiles are made from natural earth materials. These materials are then fired at very high temperatures. The final result is a dense structure similar to ceramic. The structure is resistant to:
- Fire
- UV Rays
- Insect Infestation
- Rot and Decay
- Different Types of Weathering
Clay tile roofs have often been documented to last 50 years or longer. In some cases, these roofs last even longer. However, longevity depends on environmental stress. Specifically, longevity depends on moisture and freezing temperatures. As such, tile grading becomes important.
What “Grade” Means for Clay Roof Tiles
Grading of clay roof tiles involves standardized testing. The testing determines tile performance. The tile grading procedures and testing standards in the United States are established by the American Society for Testing and Materials. ASTM International establishes structural strength and moisture standards.
The concept behind tile grading is straightforward. Tile grade means the tile’s level of weather resistance. It does not necessarily determine aesthetic value, craftsmanship, or appropriateness. The grading of each tile addresses specific conditions. The conditions include differences in moisture and freezing temperatures.
Two of the performance factors are of primary importance in grading:
1. Water Absorption Rate
Clay has a natural way of absorbing some water. Lower absorption generally means better resistance to damage from freeze-thaw conditions because there is less water in the tile to expand when frozen.
2. Transverse breaking strength
This is a measure of the amount of force a tile can withstand before breaking. Higher strength provides better resistance to stress from installation, foot traffic, and environmental forces.
These characteristics combine to determine how well a tile will survive long-term exposure to particular climates.
Grade 1 Clay Roof Tiles: Maximum Weather Resistance
Grade 1 clay roof tiles have the greatest level of weather resistance of the three classifications.
They typically have:
- Reduced water absorption levels
- Increased transverse breaking strength
- Increased resistance to freeze-thawing
- Good structural durability in harsh environments
Because of such properties, Grade 1 tiles can be installed in climates where winter temperatures regularly fall below freezing. In fact, they can perform in areas where other grades of tile may not survive even one winter season.
For this reason, they are commonly specified for:
- Cold northern climates
- Areas with heavy snow or ice
- Areas with freeze-thaw cycling
- High exposure areas
This increased structural performance, along with resistance to moisture, allows these tiles to maintain their integrity despite repeated expansion and contraction due to temperature changes.
Lifespan Expectations
If properly installed and maintained, Grade 1 clay roof tiles can last for decades, even in the most challenging weather conditions. The tiles’ resistance to moisture-related deterioration is an important aspect of their long lifespan.
Compared with other, lower-grade tiles, Grade 1 tiles are manufactured and tested to stricter standards of water absorption, as well as higher minimum standards of transverse breaking strength, properties that allow them to maintain their structural performance in areas with repeated freeze/thaw cycling.
Grade 2 Clay Roof Tiles: Moderate Climate Performance
Grade 2 clay roof tiles have an intermediate level of weather resistance. They do well in areas that have exposure to moisture but not in extreme freezing conditions.
Compared to Grade 1 tiles, Grade 2 tiles generally have:
- Higher absorption rates than grade 1
- Reduced breaking strength as compared to Grade 1
- Better performance than Grade 3
They are suitable in many parts of the world where temperatures get cold enough to freeze, but not severely or for a long duration. In these types of environments, Grade 2 tiles may offer good long-term performance, provided that the tiles are properly installed and ventilated.
Where Grade 2 Tiles are Commonly Used
- Mild winter climatic regions
- Regions with intermittent periods of freezing
- Regions with no long periods of deep freeze
- Projects that require a balance between performance and regional suitability
In the grading scale, the grade 2 tiles have higher weather resistance performance compared to grade 3 tiles, but lower compared to grade 1 tiles.
Lifespan Expectations
Grade 2 clay roof tiles can offer a long lifespan in regions with climatic conditions that are suitable for their performance rating. Their lifespan depends on combining the right climatic conditions with the right installation practices.
Grade 3 Clay Roof Tiles: Designed for Warm and Mild Regions
Grade 3 clay roof tiles are best used in an environment where freezing temperatures are minimal or absent. This means the Grade 3 roof tile has good performance in a warm and/or mild climate, which is consistent throughout the year. However, the roof tile has not been designed for exposure to freezing and thawing cycles.
Some of the characteristics of Grade 3 roof tiles include:
- Increased absorption of moisture in comparison to Grades 1 and 2
- Decreased transverse breaking strength
- Good performance in non-freezing environments
Some of the environments where the Grade 3 roof tile can be used include:
- Southern coastal regions
- Subtropical regions
- Environments with little or no freezing temperatures during the winter season
In the warmer climates, the Grade 3 roof tile can be used very effectively, and it provides the performance characteristics required for non-freezing environments.
Handmade Clay Tiles and Classification Grade 3
Many handmade clay tiles fall into Grade 3 classifications and remain widely used for architectural and aesthetic applications. However, because Grade 3 tiles are not designed for sustained freeze-thaw exposure, they are generally not suitable for colder northern climates, including many regions north of Florida.
Lifespan Expectations
In the climates for which the roof tile has been designed, the long lifespan of the Grade 3 clay roof tile can be expected. This, of course, depends on the roof tile being protected from exposure to freezing and thawing.
How to Choose the Right Grade for Your Region
Choosing the right clay roof tile grade is a matter of understanding your own local climate and how it will match with the weather resistance capabilities of the tile.
Grade 1 is recommended for:
- Northern states that experience severe freezing as a common occurrence
- Areas that have long winters and high snow
- High elevation locations of any latitude
- Projects where building codes require severe frost resistance
Grade 2 is appropriate for:
- Mid-Atlantic & Transitional Climate Zones
- Areas where it freezes sometimes, but not for a long period of time, or severe
- Areas in which moderate frost resistance is adequate according to local codes
- Projects where budget is a consideration
Grade 3 is suitable for:
- More southern coastal areas, such as Florida, coastal Texas, and Southern California
- Desert climates, little rainfall, no freezing
- Areas where aesthetic variety and handmade character are a priority
- Projects where resistance to freeze-thaw is not required
In addition to climate, think about your specific project requirements. In some projects, design requirements, building codes, or environmental exposure levels may influence the specified grade. The appropriate choice depends on matching tested performance characteristics to local climate conditions.
In terms of tested weather resistance performance, Grade 1 provides the highest level of resistance, followed by Grade 2, then Grade 3. This hierarchy is based on differences in exposure tolerance, particularly to moisture and freeze-thaw conditions, rather than a universal ranking of overall usefulness.
What Affects The Lifespan of Clay Roof Tile Products
What Affects The Lifespan of Clay Roof Tile ProductsWhile grade is the number one factor in weather resistance, other elements play a part in how long your clay roof tiles will last.
1. Installation Quality Is Very Important
Even the best Grade 1 tiles won’t reach their full potential without proper installation. Proper underlayment, proper fastening techniques, adequate ventilation, and attention to the details of flashing all matter. Work with installers who are certified by the manufacturer or the Tile Roofing Institute.
2. Maintenance Will Extend The Life Of Any Roof
Clay tiles are low-maintenance, but not no-maintenance. Regular inspections for cracked or out-of-place tiles, keeping valleys and gutters free of debris, and addressing issues promptly will prevent minor problems from escalating into major failures.
3. The Underlying Roof Structure Needs To Be Good
Clay tiles are heavy. If your roof deck and framing are insufficient to support the load, you will have structural problems that have nothing to do with the tiles at all.
4. Local Environmental Factors Other Than Temperature Are Also Important
Coastal environments with salt spray, areas with heavy pollution, or areas with high UV exposure can all affect the longevity of a tile. Tiles with higher weather-resistance ratings may provide greater tolerance, but installation and maintenance are essential.
5. Quality Of Manufacturers Varies
Not all clay tiles are created equal, even within the same grade. Working with established manufacturers that follow the standards for the American Society for Testing and Materials, which are the standard in the ceramic tile world, and have a track record of success, will ensure you’re in a position to receive tiles that are actually performing as advertised for their grade.
Verea Clay Tile produces tiles across all three performance classifications, enabling projects to be specified based on regional climate, structural requirements, and design goals. Our Tiles are tested to meet ASTM C1167 specifications and provide technical support to ensure contractors and homeowners select the appropriate grade and install them properly.
The Bottom Line on Clay Tile Roofing
Clay roof tiles can last for even 100 years or more, as long as the correct grade is matched to the correct climate conditions. The grading system is there to help you make the right match.
Tile grades offer different levels of tested weather resistance. The grade 1 tiles offer the highest resistance to weather, grade 2 tiles offer average resistance, while grade 3 tiles offer the lowest resistance, which is suitable for regions with minimal or no freezing.
The key to making the right choice is to understand the climatic conditions, check with local building codes, and work with qualified roofing professionals to make the right choice.
Contact our team today to get started!