Loose tiles and cracked hearths fixed in Wedgewood Groves

When a raised firebox allows a thinner extension

The same code section carries an exception. Where the firebox opening starts 8 inches or more above the top of the hearth extension, a 3/8 inch layer of brick, concrete, stone, tile or other approved noncombustible material is thick enough for the extension.

Many raised fireplaces qualify and many flush ones do not. We measure the height from the extension to the bottom of the opening before recommending a thin replacement finish, because the tile that is fine in front of a raised firebox can fall short in front of one set at floor height.

Hearths in front of factory-built fireplaces follow the listing

A factory-built fireplace plays by different rules. Section R1004.2 says its hearth extension is installed in accordance with the listing of the fireplace, so the manual that came with the unit sets the size and the materials.

One maker's wood-burning model, for example, calls for an extension reaching at least 20 inches in front of the opening and 12 inches beyond each side, and another model can differ. We find the model on its rating plate before measuring, so the repair follows the right document.

• Model found on the rating plate
• Manual read for hearth size and layers
• Repair matched to that document

Replacing one cracked tile on a sound hearth

A single cracked tile over a solid base is the simplest hearth repair. The tile is cut out without disturbing its neighbors, the old setting bed is scraped back, and a replacement is set flush and grouted to match.

Everything depends on that base being sound. Before promising a one-tile repair, we check the tiles around it and the base under it. If the crack came from movement below, a new tile would only crack again, and we tell you that before you pay for it.

Slate hearth tiles that flake or split

Slate splits in layers, and on a hearth those layers can begin to lift at the edges of a tile. A flaking surface catches ash, looks worn and gets worse under foot traffic.

Light flaking can sometimes be trimmed back and sealed. Tiles coming apart deeper are replaced. Because slate varies from lot to lot, we discuss color and thickness before ordering, so the new tiles sit flush with the old ones.

• Light flaking trimmed and sealed
• Deeper splits replaced
• New tiles matched for color and thickness