How to Repoint a Brick Fireplace
Unsightly cracked and crumbling mortar can be fixed in minutes with a few simple tools
The mortar in most brick joints consists of sand, lime, and portland cement. But in a fireplace, that mix just crumbles away when subjected to roaring wood fires. For this application, masons rely on a refractory mortar made of magnesium silicate, which can withstand heat up to 2,000 degrees F. Yet even refractory mortar can fail as the brickwork expands and contracts with repeated fires.
Fortunately, fixing those damaged joints is a snap, thanks to high-temp fireplace mortars packaged in caulk tubes, such as the one shown above. The old, messy way of repointing—mixing mortar in a bucket and troweling it on—is a thing of the past. Mark Schaub of Chimney Savers shows how easy the job is now. (Schaub appears regularly on TV episodes of This Old House.)