What Do I Use to Patch a Broken Piece of Slate?

New Slate

• If your slate roof tile is cracked, your best bet is to replace it. When slate cracks, it loses its integrity and can no longer be trusted to protect against falling objects or moisture damage. Cracks have radiated below the surface where you cannot see them. Buy new slate tile and replace the piece entirely to ensure structural stability and keep future problems from occurring.

Cutting Slate

• You may need a way to cut the replacement slate tile to fit a particular area. With the bevel side of the tile face down, scribe the tile and then carefully cut it. Tile snips are designed for the job, as well as carbide-edges wet saws for more detailed work. If you do not want to go to the extra expense of using these tools, a sharp blow with a trowel may be able to make a clean cut, but this can also damage your tile.

Nails and Flashing

• Nails and flashing hold the slate tile to the roof and prevent leaks on the sides. If you are preparing to replace or patch slate, you need extra materials to attach the new tile, too. Often, the old nails have been corroded, and flashing may need to be replaced if it is causing leak damage. A slate hammer can help you avoid pounding in new nails too tightly and damaging the slate again.

Epoxies and Grouts

• If you are dealing with a large slate piece, a tile that is part of an ornate design and difficult to replace, or a slate piece that you cannot remove for a different reason, you may be able to repair it. Epoxy glues can be used to fill in the surface and then covered with grouting sand or a similar material to bring it level with the slate stone. Mortars are available with polymer elements to save time and fix small cracks or chips on slate both indoors and outdoors.