Slate is a natural stone product that is primarily made up of hardened clay and ash. It is usually identified by its dark gray hue, though it may range in color depending on the source of the material. Slate is often used to build floors and roofs, and is also a popular material for finishing the exterior and interior walls of a building. When it is used to cover or construct walls, it is referred to as slate cladding or siding.
This material can be used indoors as a full wall covering or to act as a trim or wainscot. Slate cladding is available in large flat panels or smaller tiles that are similar to porcelain or ceramic. When designed for indoor use, the slate is cut very thin to reduce its weight and give homeowners more flexibility when it comes to installation. Slate cladding is frequently used around fireplaces, in showers, or to create a backsplash above kitchen counter tops.
When used outdoors, slate cladding can be installed similarly to traditional brick siding. It is cut into small blocks, known as sculpings, and is erected using brick ties and masonry mortar. Like other types of stone siding, this type of installation is designed as a curtain-wall system. This means that the stone finish surface is self-supporting, and is separated from the structural walls of the building by several inches to allow for drainage.
Slate cladding is also available in the form of large panels or shingles for installation on exterior walls. Both of these products can be installed over concrete or cement board using masonry mortar, and are similar to traditional stone veneer. In this type of application the slate shingles or panels must be cut very thin to minimize stress on the building structure.
One of the primary benefits associated with slate is its rich natural coloring and tightly-grained appearance. This material also offers a high degree of fire protection and durability, and requires little to no maintenance. Slate can be expected to last for decades on either an interior or exterior application, and is strong enough to withstand elements like rain, wind, snow, and ice.
Like other stone products, slate can develop a white, powdery discoloration over time that can detract from its natural beauty. This effect is known as efflorescence, and occurs when salt deposits within the stone seep through the material's pores and reform on the surface. Efflorescence should dissipate over time, or it can be removed using chemical cleaning systems. Slate is also fairly expensive compared to other cladding materials, though the added upfront costs should be balanced against the lifespan and maintenance requirements for each product.