How thick is roofing slate?

It is important when purchasing a new slate roof or slate roofing repairs that the contractor is specific as to the type and thickness of the slate proposed….

Standard Thickness: Defined as 1/4″ slate of nominal thickness, +/- 1/16″. Shingles are hand-picked to be of uniform thickness with no more than 1/8″ variation in surface face dimensions. Surface texture will be smooth with no knots and knurls.
Textural Slate: Defined as 3/16″ to 3/8″, or 3/8″ to 1/2″, or 1/2″ to 3/4″, or 3/4″ to 1+” of nominal thickness. Thickness variations should be anticipated. Compared to standard roofs, the textural roof is likely to have more character due to pronounced shadow line.
Intermingled Rough Texture: Defined as a roof with a least three distinct variations in slate thickness; for example, slate of 1/4″–3/8″, 3/8″–1/2″, 1/2″–3/4″ thickness used in one roof. The most pronounced texture is achieved by using a greater percentage of the thinnest material and a lesser percentage of the thickest material.