How is Stone-Coated Metal Roofing Different from Metal Roofing?

Stone-coated metal roofing is made from steel sheets, and then coated with stone granules.

The steel sheets make the perfect substrate since they can easily be “stamped” into a wide variety of shapes. The stone-coating process allows for a wide variety of vivid colors and textures that can replicate the look of traditional roofing materials like asphalt shingles, clay tiles and wood shakes. This is what gives stone-coated metal roofing products, such as DECRA Metal Roofing, the design versatility to suit any style.

The Stone-Coated Metal Roofing Manufacturing Process

The stones in DECRA’s stone-coated metal roofing products are called roofing granules. The granules are manufactured from natural stone which was mined at a quarry, then crushed and screened to various sizes. The granules are manufactured in such a way that when applied to and embedded in our DECRA acrylic base coat, the particles fit together to provide the maximum coverage for our roof panel surface.

Several characteristics are critical when analyzing and selecting an appropriate and suitable stone, including:

• Hardness
• Opacity to solar ultraviolet light
• Chemical and physical inertness to provide resistance to acid rain and leaching
• Durability to freeze/thaw and wet/dry cycling
• Minimal oxidation and rusting (iron content)
• Low porosity
• Suitability for coating
• Particle shape

The granules achieve their vivid colors through a process where the stone particles are coated with a combination of pigments similar to paint. The pigment slurry mixture, once applied to the stone, is baked on at high temperatures causing the pigment mixture to coat the stone in a ceramic process. Pigment selection will determine the final appearance and color of the roofing granule.

Multiple color readings, using a spectrophotometer, are performed at different intervals during the manufacturing process.

Color fixation tests are also conducted to make certain that the pigmentation has adhered properly to the stone granule – ensuring that the color will remain stable over time. Given the intense solar UV exposure on a roof system, roofing granules must prove to be durable. DECRA utilizes state-of-the-art computerized roofing granule blending and application machinery to ensure a quality stone coat manufacturing process.