Cladding over an old brick fireplace
This fireplace will soon have a new gas insert. The original marble mantle and wood surround will be replaced with vintage-looking tile. The existing mantle and surround didn't match the 1930's styling of the rest of the house.
I found two different types of brick when we removed the mantle and wood surround.
To build up the hearth, I built a form with 1x4"s, then applied fat mud against the wood form and at the opening to the fireplace. Deck mud was applied inside the fat mud perimeter. We have found that deck mud shrinks less than fat mud and provides for a stronger base.
Here I am using a powder actuated nail gun to attach the metal lath. This is a Ramset gun, the strength of the charges used depends on what you are driving the nails into. The charges are color coded for strength and you want to use just the minimum strength needed for the surface. Here I used the brown coded powdered charges to install the fasteners into the brick mortar joints. The nails have washers attached to better grip the lath.
It's important to set the hearth first and make it as level as possible to ensure that all vertical tile work is level.
To keep the tile level I continuously checked all rows of tile.
It is also important to keep both legs plumb. Keeping the tile on the face both level and plumb ensures that the mantle will be level.
A form of kiln-dried wood was built for the mantle.
The wooden frame of the mantle was then clad in HardiBacker board. This is a very important step. If the tile was set directly onto the wood we would have adhesion problems as soon as the fireplace generated heat. When attaching the HardiBacker board to the wood form, it is important to use non-modified thinset. Extreme heat generated by the fireplace will degrade the polymers in modified thinset.
Although the finished mantle looks like wood, we actually found hand-crafted ornate chair rail tiles. All the tiles for the fireplace were manufactured by Pratt and Larson in Portland, OR.
I installed the chair rail trim tiles over the Hardibacker.
Because I have three colors of tile I selected a grout, Urban Putty by Customs, that compliments but does not match any of the tile colors. This ties everything together without blending in to any particular tile color. An added benefit of a tile mantle is that ceramic tile radiates tremendous residual heat after the fireplace is turned off.