How to Add Tile or Marble to Fireplace Mantels

Clear the room of all furnishings and cover the floor with a drop cloth in front of the fireplace to catch debris from the tiling process.

Sand the surface of wooden and marble mantels with medium grade sandpaper to create a rough surface texture. Roughen brick and stone mantels with a handheld concrete grinder. Wipe the surface clean with a rag.

Measure the mantel space and then arrange the tiles or marble in a test pattern that fits the measured space while being visually appealing. Use as many full tiles and slabs as possible in the arrangement with spacers between the test pieces to get an accurate layout.

Mix a batch of thinset mortar in a bucket using an electric drill equipped with a paddle attachment. Allow the mortar to sit for 10 minutes, then stir thoroughly.

Apply mortar to the mantel with a notched trowel. Spread the mortar to 1/4-inch thickness with the flat of the trowel. Tilt the trowel at a 45-degree angle and run the notches on the edge of the trowel over the mortar surface to raise ridges that will adhere better to the tile or marble than a flat mortar surface.

Mount the ceramic tile or marble beginning at the center of the shelf and working outward to each edge, if tiling only the mantel top, then tile the facing pieces. Start at the bottom of each side of the mantel and work towards the edge, if tiling the entire mantel or fireplace facing. Place spacers between the tile or marble slabs to create a uniform appearance. Move up to the next row, providing spacers between the separate rows. Continue to place rows of full tiles and marble slabs until you only have partial tile spaces remaining.

Cut the tile or marble to create partial pieces for the remaining mantel spaces. Measure the partial space and then mark the line to cut on the tile. Cut the tile down the marked line with a tile cutter equipped with a blade manufactured for your tile type. Use a wet saw to cut the marble slabs to fit. Mark the cutting line on the slab and then place masking tape along the mark as a cutting guide. Align the cutting line with the saw blade and then run the slab through blade. Sand the edge of the slab beginning with 80-grit sandpaper and working towards 400-grit sandpaper to make the edge as smooth as the face of the marble.

Mount the partial tile and marble pieces in the space on the mantel that you cut them to fit. Wait 24 hours for the mortar to set.

Remove the spacers and mix a batch of grout for filling the joints between the tiles or slabs. Apply the grout using a grout float to spread the material into the joints. Wipe the surface with a damp sponge within 15 minutes to remove excess grout. Wait two hours and then wipe the surface with a clean, lint-free cloth to remove grout residue, preventing a dulling haze. Wait the period of time recommended by the grout manufacturer for the grout to cure.

Seal the tile or marble with a grout sealer formulated for the type of material used to cover the fireplace mantel. Brush the sealant onto the entire mantel surface, and then wait 48 hours for the sealant to dry before using the mantel.