With a 75 year warranty, Ironstone Porcelain Roof Tiles offers beauty and durability. Beautiful, lightweight and guaranteed to last. Ironstone adds warmth, character and charm to any architectural style. Our proprietary process duplicates the beauty and elegance of genuine slate and wood in exacting detail. It's hard to tell the difference, until you see the price. Unlike cedar, concrete or traditional ceramic, Ironstone is virtually impervious to water making it resistant to moss, mold, mildew and freeze-thaw damage.