Can I Use Premixed Thin-Set for Slate?

Basics

• Slate tile is versatile and has gained in popularity for use as flooring. It creates a durable and long-lasting floor that is fireproof, waterproof and easy to keep clean. Moreover, it makes an attractive floor surface that is equally suited for use either indoors or outdoors. Slate tiles held in place by thin-set can be placed over either a concrete or a wood substrate floor.

Thin-Set

• Thin-set is a type of mortar used to set various types of tile, including slate, to a floor. After the thin-set dries, it permanently attaches the tile to the substrate, so the tile does not move. Thin-set is a combination of Portland cement and very finely graded silica sand with a water-retention compound mixed in. The chemicals in the water-retention compound allow the cement to hydrate properly by helping the water to mix thoroughly with the mortar.

Mixing

• Using a premixed thin-set mortar is easier than mixing it. Nevertheless, Tim Carter, who writes the nationally syndicated newspaper column "Ask the Builder," recommends mixing it from dry powder instead of using the already mixed form. After thin-set mixes with water, it becomes an extremely tacky mortar that adheres to anything. However, it does not flex after it dries. Therefore, Carter recommends not beginning to mix the thin-set until after you have the spacing of the slate correctly figured by dry laying the tile.

Miscellaneous

• Using thin-set mortar for slate tiles only requires a very thin layer. Apply it in a layer no more than 3/16 inch thick. After positioning a slate tile, either press it firmly in place or tap the tile lightly with a rubber mallet. Use a damp sponge immediately to remove any thin-set mortar from the face of the slate tiles. Allow the slate to set in place for at least 48 hours after finishing the floor before walking on it.