Tile over brick...with a problem

Question

We have this giant brick fireplace in a home we just purchased. As part of our renovations, we plan on covering the brick with tile and putting a simpler mantel on top. The hearth and surround was brick and the sides and top edge of the brick was covered by the old mantel.

We removed the brick hearth and had just planned on just covering the old brick surround with tile. When we removed the mantel, we discovered that the builder hadn't finished the brick surround fully because it would be covered by the edges of the old mantel.

Whats the easiest way to ... 'fill in' the unfinished area so we can tile over it.

Answer 1

You want something with close to the same thermal and moisture properties as the rest of the surround. Best wound be a piece of brick. You could bond it in with thin set since it is not really structural.

If none are handy, you could use pieces of tile layered using thin set to glue it in. Just make sure none of the pieces stick out more than the brick.

You might want to put a skim coat of the set over the whole brick face before tiling to give you a smoother base for a more even finished surface. This ski coat would cover any irregularities with a pieced tile patch.

Answer 2

You could probably install tile backer board right over the brick. Apply thinset to the brick and backer board to make sure it bonds. Then attach it with backer board screws. If those don't go in, then you can use a few masonry screws to hold it until the thinset cures. That way you can square up the opening and have a good flat surface to tile to.

Once the backer board is up, you can fill the voids with mortar on the top.