Chimney Pointing

The mortar between your bricks is the glue that holds your chimney together, but it's also the most vulnerable part of the whole structure. Brick is tough, but mortar is a soft mixture of sand, lime, and cement. It’s designed to be the sacrificial lamb—it takes all the punishment from the weather so the bricks don’t have to. When you look at an older chimney, the first thing you’ll notice is that the mortar joints are often recessed, crumbling, or simply gone in certain spots. That's a huge problem, and fixing it is called **chimney pointing** or **tuckpointing**. Chimney pointing is necessary because, over time, that soft mortar absorbs water. In winter, when the temperature drops below freezing, that water expands by about 9%. This expansion acts like a miniature explosion, slowly pushing the mortar away from the brick face. This cycle of absorption, freezing, and expansion—what we call the **freeze/thaw cycle**—is the number one enemy of masonry. After decades of this, the mortar joints start to look like sand, they get crumbly, and they open up little channels for water to run straight into the chimney structure. Once the mortar joints are open, the chimney starts leaking, and the internal damage accelerates. Water soaks into the brickwork, reaches the inside of the flue tiles, and speeds up the decay of the entire chimney. This is when you start seeing water stains inside your house, white chalky deposits (called efflorescence) on the outside of the brick, or pieces of concrete or mortar on the ground around the chimney base. Our tuckpointing process is a permanent solution. It is not just about slapping new mortar over the old cracks. That’s a temporary fix that traps water and makes the problem worse. The right way to do it starts with carefully **grinding out** the failing mortar joints. We use specialized, thin diamond blades to remove the old, crumbling material to a depth of about half an inch. This gives us a clean, solid surface to bond the new mortar to. We then clean the joints thoroughly, often with pressurized air, to remove any dust or loose fragments. The type of mortar we use is crucial. For older, historic homes, we might use a softer, historic lime-based mix, but for most modern Suffolk County chimneys, we use a strong, weather-resistant **Type-S mortar**. Type-S has a high tensile strength and is specially formulated to stand up to our coastal weather conditions, salt air, and heavy rain. We mix the mortar in small batches and color-match it as closely as possible to the existing joints using mineral pigments, ensuring the finished repair blends seamlessly with the original brickwork. Next comes the packing. Using a special tool called a pointing trowel, our masons pack the new mortar firmly into the freshly ground-out joints. This isn’t a quick process; every single joint must be fully compressed and filled to be watertight and strong. After the mortar has cured slightly (it has a specific drying time, usually 30 minutes to an hour depending on the weather), we use a jointing tool—like a rake or a slicker—to give the new joint the same concave or weathered finish as the original chimney. This finishing process, called **tooling**, is essential because it compresses the surface of the mortar, making it even more resistant to water penetration. We never rush the cure. We prefer to do our pointing work on dry days, and sometimes we cover the chimney with tarp overnight to protect the fresh mortar from dew or sudden rain. Once the new mortar has cured, we usually apply a full-spectrum **water repellent sealer** to the entire chimney stack. This sealer is a breathable, clear liquid that soaks into the brick and mortar, making it hydrophobic (water-shedding) without changing its appearance. This step adds a final layer of insurance against the freeze/thaw cycle, effectively making the chimney waterproof. Chimney pointing is a heavy-duty, long-term repair. Done correctly, it restores the structural integrity of your chimney and stops those leaks for decades to come, giving you peace of mind that your home’s structure is secure.