Slate is a fine-grained, metamorphic rock formed from clay or volcanic ash. Its durability, natural beauty, and ability to be split into thin sheets make it ideal for roofing.

Slate offers exceptional longevity (often 100+ years), superior fire resistance (Class A fire rating), weather resistance, and a timeless aesthetic. It can also significantly increase a home's resale value and overall prestige.

Yes, slate is a 100% natural material, quarried with minimal processing and boasts an incredibly long lifespan, reducing the need for frequent replacements. Choosing California Slate minimizes environmental impact compared to many other roofing materials.

California Slate is available in a diverse palette of natural colors from around the world, including a range of grays, blacks, greens, purples, and earthy multi-colors. The specific hues and tones vary depending on the slate's origin and mineral composition.

Some slates are "unfading," meaning they retain their original color. Other slates may "weather," exhibiting subtle color changes over time, which many find adds to their unique character and charm.

In roofing, a "square" is a unit of measurement equivalent to 100 square feet of roof area. This standard unit helps in estimating the amount of roofing material needed for a project.

California Slate Company provides a variety of premium slate types, including traditional full-weight slate and our innovative lightweight SLATE2™ system. Each type boasts unique characteristics, colors, and textures to suit any architectural vision.

We meticulously source our premium ASTM S-1 slate from the world's most renowned and reputable quarries, including Vermont, USA, Spain, and Brazil, to ensure unparalleled quality and consistency.

SLATE2™ is our revolutionary lightweight slate roofing system, designed to deliver the authentic beauty and durability of genuine natural slate while significantly reducing roof load. It makes a slate roof suitable for a wider range of homes, often eliminating the need for costly structural enhancements.

While California Slate Company primarily supplies premium slate materials, we are happy to refer you to qualified and experienced slate roofing contractors in your area who specialize in installing our products.

Our genuine slate products are backed by a 100-year limited warranty, a testament to their enduring quality and our confidence in their performance. Please refer to our detailed warranty document for complete terms and conditions.

The thickness of roofing slate can vary, with a standard slate typically ranging from 1/4" to 3/8". However, some slates are available in 3/16”- ¼” or up to 1”- 1 ¼” thickness. The availability of different thicknesses depends on the specific slate and quarry.

The natural color of slate, including shades of brown, is determined by its specific mineral composition and the geological conditions under which it formed. Iron oxides and other minerals within the clay or volcanic ash can impart unique brown, tan, or even multi-colored hues to the slate. The characteristics of weathering are specific to Vermont slates and not Spanish or Brazilian slates which are Unfading. Vermont Semi-Weathering and Weathering slates will yield, over time, a variety of rich earth tones. When extracted from the quarry they are monochromatic. For Semi-Weathering Some slates, about 10-25%, will gradually change to soft tones of buffs and tans after exposure to the weather. The degree of change for Weathering slates can range from less than 30% to more than 90%. For either type of slate this process begins 1-2 years after exposure to the climate. This weathering continues to some degree throughout the life of the slate but does not diminish the longevity of the material. The weathering process is unpredictable and not guaranteed. These states have been quarried since the mid-19th century.

The portion of the slate that is exposed to the weather is called the "exposure." This is determined by the length of the slate tile and the headlap. For instance, an 18-inch slate with a 3-inch headlap would have a 7.5-inch exposure. The exposure contributes significantly to the visual pattern and aesthetic of the installed slate roof.

The weight of slate varies depending on its size and thickness. While traditional slate is heavier than some roofing materials, our SLATE2™ system offers genuine slate at under 6 lbs. per square foot for 1/4"-3/8" thick slate and under 9 lbs. per square foot for 3/8"-1/2" thick slate, significantly reducing structural considerations. Our technical specifications provide detailed weight information for each product.

Slate roofing is rigorously graded according to ASTM C406 standards. S1 is the highest grade, indicating the highest quality slate with the longest projected lifespan, which is the standard we uphold for our premium products.

To accurately determine the number of squares needed, you'll first measure the total surface area of your roof in square feet. Then, divide that total by 100. It's always advisable to add a percentage for waste, especially with natural materials like slate, to ensure you have enough for cuts and potential breakage. For precise calculations, we recommend consulting with a qualified roofing professional.

Headlap refers to the shortest distance between the butt (bottom edge) of a slate tile and the top edge of the slate in the course two courses immediately below it. It's crucial for ensuring a watertight roof, as it dictates how much overlap each slate has with the ones beneath it, preventing water from penetrating the roof deck. Proper headlap is essential for the long-term performance and integrity of a slate roof.

For optimal performance and water shedding, slate roofing is best suited for roofs with a minimum pitch of 4:12 (4 inches of rise over 12 inches of run), though specific product lines may allow for lower pitches. Consulting our detailed installation guides is recommended for specific product line recommendations.

For the application of slate roofing, a robust and rigid roof decking is essential to provide adequate support for the weight of the slate. Typically, this involves solid sheathing such as plywood or tongue-and-groove boards, ensuring a smooth and continuous surface for proper installation. The specific decking requirements may vary based on local building codes and the selected slate system.

Yes, slate can be used for siding and other architectural applications, offering the same beauty and durability as a roofing material. California Slate Company can provide specific product recommendations and guidance for slate siding projects.

Slate is typically cut using specialized tools like a slate hammer and slate cutter, requiring specific techniques. Professional installation by experienced slate roofers is highly recommended to ensure proper cutting, fitting, and overall integrity of your roof.

Should a slate become damaged, it's crucial that replacement be performed by a qualified slate roofer. Proper repair techniques ensure the integrity and longevity of your California Slate roof.

The cost of a California Slate roof varies depending on factors such as the chosen slate type, roof size, architectural complexity, and installation labor costs. While a premium investment, a slate roof offers unparalleled long-term value and beauty. Contact us for a personalized quote.

You can request a free, no-obligation quote through our website's contact form, or by calling us directly at 888.994.0842

Yes, we work with architects, homeowners and contractors.

Freight charges for slate can vary significantly based on the quantity of slate, its weight, the shipping distance, and current fuel costs. Due to the natural weight of slate, freight is a notable component of the overall cost. For an accurate estimate of freight charges for your specific project, please contact us directly with your order details and delivery location.

What is natural slate, from an architectural perspective? Natural slate is a high-density, fine-grained metamorphic rock, renowned for its exceptional durability, inherent water resistance, and natural clefting ability. Architecturally, it provides a timeless aesthetic coupled with unmatched structural integrity and longevity, making it a premier choice for enduring designs.

ASTM C406 is the authoritative standard for roofing slate, classifying material based on critical physical properties and weathering resistance. S1 is the highest classification, indicating slate of superior quality with the longest projected service life—exceeding 75 years and often extending to 150 years or more. California Slate Company exclusively provides S1 grade slate, guaranteeing that your specifications meet the highest industry benchmarks for durability and long-term performance.

California Slate is available in various thicknesses, the standard typically ranging from 1/4" to 3/8". Thickness directly impacts the roof's aesthetic depth, shadow lines, and overall durability. Thicker slates offer a more robust appearance and can provide enhanced impact resistance.

Traditional natural slate can be a substantial roofing material, requiring consideration for structural design. However, our innovative SLATE2™ system significantly reduces this load. SLATE2™ utilizes genuine ASTM S-1 slate and installs at under 6 lbs. per square foot for 1/4"-3/8" thick slate and under 9 lbs. per square foot for 3/8"-1/2" thick slate. This lightweight profile often eliminates the need for costly structural enhancements in both new construction and re-roofing projects, broadening the applicability of natural slate.

California Slate tiles are supplied in a wide array of dimensions to achieve diverse architectural expressions. Common sizes accommodate standard exposures such as 8-inch straight applications, alongside options for varied lengths and widths to create custom patterns or rustic staggered effects. Precise dimensions and available cuts are detailed in our product data sheets.

As a natural quarried stone, California Slate exhibits inherent variations in color, markings, thickness, and texture. These natural differences are not defects but are defining characteristics that create a roof of unparalleled authenticity and unique beauty that cannot be replicated by manufactured products.

Natural slate is inherently non-combustible. Our SLATE2™ system, when installed with a Class A board or shield beneath, achieves a Class A fire rating per ASTM E-108. This provides the highest level of fire protection for your structure.

California Slate systems are engineered for superior resilience: Wind/Rain Resistance: Our systems have passed TAS 100 A protocols for 110 MPH wind/rain (Dade County Protocol), demonstrating exceptional resistance to severe weather. Hail Impact: Our 1/4"-3/8" thick slate (under 6 lbs/sq ft) is rated Class 3 per FM 4473, and 3/8"-1/2" thick slate (under 9 lbs/sq ft) is rated Class 4. These ratings assure robust protection against hail damage.

California Slate boasts an exceptional lifespan of 100+ years. There are roofs around the world with 300 year old slate on them today. With regards to Slate2, the specialized interlayment within our SLATE2™ system is designed to provide weather and UV deterioration protection for at least 50 years, ensuring the longevity of the entire roofing assembly.

While natural slate generally possesses a lower Solar Reflectance Index (SRI) compared to highly reflective "cool roof" materials, its high thermal mass contributes significantly to energy efficiency by slowing heat transfer. This can lead to reduced cooling loads in warmer climates by stabilizing indoor temperatures and mitigating the urban heat island effect over the very long lifespan of the roof. Specific SRI values vary by color; consult individual product data sheets for precise figures.

California Slate is a 100% natural, inert material requiring minimal processing, which inherently reduces its embodied energy compared to manufactured roofing products. Its exceptional longevity directly reduces landfill waste from re-roofing cycles, making it a highly sustainable and environmentally responsible choice for green building initiatives.

While California Slate Company primarily focuses on North American ASTM standards, CE (Conformité Européenne) certification is a specific requirement for products sold within the European Economic Area. Architects designing for international projects should consult with our technical team to determine if specific product lines meet relevant CE directives or other country-specific certifications. We are committed to supporting your project's compliance needs.

Yes, California Slate Company offers comprehensive technical resources for architects, including detailed CAD drawings, specification templates, and information regarding how our products can contribute to LEED (Leadership in Energy and Environmental Design) points and other green building certifications. These resources are available through our architectural support channels.