Bricks inside a fireplace are often unsightly and the do-it-yourselfer may ponder cladding the bricks with a porcelain tile. However, this is not an appropriate use for porcelain tile. After withstanding the heat inside a fireplace, porcelain tile will most certainly crack, and possiblyr even explode, as the fireplace cools. Installing any kind of tile inside a fireplace -- even durable, dense porcelain tile -- is an extremely bad idea.
Tile companies produce both ceramic and porcelain tile labeled "heat resistant." This type of tile is well suited for a fireplace hearth application and can withstand hot items in a kitchen. However, the term heat resistant does not apply to the inside of a fireplace where temperatures far exceed the heat-resistant qualities of porcelain tile.
National and international building code stipulates the use of high-heat-compliant materials for the construction of fireplaces. Building code forbids an introduction of any non-specialized material within the fireplace. Therefore, installing porcelain tile inside a fireplace violates building code.
Special high-temperature bricks, called "firebrick" or "refractory brick", installed with refractory cement are the only materials suitable for the inside of a fireplace. Refractory bricks and other refractory materials can withstand temperatures up to several thousand degrees Fahrenheit. Porcelain tile cannot withstand high temperatures inside a fireplace.