It’s a tedious restoration process not meant for those with a fear of heights
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While brick chimneys are extremely durable and last for decades, occasional repairs may be needed for safety, efficiency, and even appearance. Repointing, one of the most common chimney repairs, tackles all three of these areas. It’s the process of replacing old mortar joints with fresh new ones, and it helps chimneys work better, stick around longer, and look as good as new. This step-by-step guide will walk through how to repoint a chimney from start to finish.
Repointing a chimney offers several improvements to your chimney that make it worth the time, effort, and money:
Appearance: For starters, repointing a chimney makes it look much better, possibly like new, as long as the bricks are in good shape.
Structural Integrity: Mortar joints keep chimneys intact, so restoring them strengthens structural integrity and improves a chimney's safety and longevity.
Waterproofing: Repointing prevents chimney leaks when it rains or snows.
Cost-saving: Sometimes—though not always—repointing a chimney helps homeowners avoid more expensive repairs in the future, like a full chimney rebuild.
Repointing involves a lot of repetitive actions—namely, removing and reapplying mortar—but no chimney is the same, so knowing all the tricks and tips ensures that the project goes smoothly. The seven essential steps to repointing a chimney are inspecting the chimney, removing the old mortar, brushing off dust and debris, wetting the mortar joints, mixing the new mortar, applying the new mortar, and cleaning and smoothing the new mortar. Here’s a closer look at each step of the process.
If you’re considering repointing your chimney, there’s a good chance you’ve already inspected it to a degree. The exterior might be visibly deteriorated or misshapen, or you could be experiencing a leaking chimney. Assess the chimney’s condition (or contact a local chimney inspector) to determine if repointing is the best path forward. If the chimney has severe structural damage, a complete rebuild might be needed.
Use a plugging chisel and drilling hammer to remove the old, crumbling mortar joints. Simply place the plugging chisel against a mortar joint and tap the back of it with the hammer until it chips away. It’s imperative you don’t remove the mortar too deeply; otherwise, it could destabilize the chimney. Aim to remove the mortar at a depth between .5 inches to 1 inch.
Old mortar joints don’t come out perfectly intact. Instead, a lot of shards and dust are left behind. As a result, we recommend cleaning the mortar joints with a soft bristle brush until all debris is gone. It makes applying the new mortar much easier when you get to that step. A compressed air sprayer could also be handy here but isn’t required.
Thoroughly dampen the mortar joints with a spray bottle or low-pressure sprayer. Doing so prevents the new mortar from drying out too quickly, which could actually damage your chimney. This step is especially important when working in hot weather. While you want to fully saturate the mortar joints, ensure your sprayer is gentle enough that it doesn’t crack or remove any of the old mortar.
You can purchase a premixed mortar or mix your own with a combination of sand, cement, and possibly hydrated lime. If you buy premixed mortar, Type N is usually best for brick chimneys. If you’re mixing your own, the general rule is to use three parts sand to one part cement. Different ratios will adjust the mortar’s firmness, but make sure the dried mortar is softer than the bricks.
Using a trowel, fill the mortar joints with the wet mortar mixture. You can scrape away excess mortar with the edge of the trowel to ensure smooth and uniform mortar joints. A masonry hawk is an optional tool that can help with the straight lines involved in chimney repointing. Try not to get mortar on the exterior of the bricks, but if you do, scrape it off before it dries.
Even if you smoothed out the mortar with a trowel while applying it to the chimney, a little more work is needed to make it look perfect. A tuck pointer is a terrific tool for this step. It allows users to condense and smooth mortar with precision, eliminating air bubbles. Wait several minutes until the mortar begins solidifying, and then clean it up with a tuck pointer. After more time passes, brush down the chimney to finish the job.
Given the safety risks associated with any rooftop construction project, we recommend that most homeowners hire a local chimney repair service for repointing. These professionals are trained to work safely at the heights required for chimney repair. Plus, you can rest assured that the job will be done properly.
Of course, the downside to hiring someone for the job is that it’s more expensive. The cost to professionally repoint a chimney ranges from $500 to $2,500 depending on the chimney’s size and condition. Another way to gauge the cost is that it’s between $4 and $25 per square foot of work. Most of that money covers labor expenses, as the supplies are cheap, but the work itself is time-consuming. So, if you feel comfortable working on your rooftop, you can save money by repointing the chimney yourself.
Tuckpointing and repointing are similar masonry techniques used to fill masonry joints. The main difference is that tuckpointing involves two different colors of mortar. One of the colors is meant to match the accompanying bricks, while the other color serves as contrast. Repointing, on the other hand, only involves one color of mortar.
Yes, it’s possible to repoint a chimney in the winter. However, repointing a chimney in inclement weather is more dangerous, especially if the roof is slippery. Another caveat is that mortar should ideally be applied when the temperature is above 40 degrees. So, even though it’s possible, other seasons are generally better for repointing a chimney.
Any type of chimney that contains masonry can be repointed. That primarily means brick chimneys, but it can include stone chimneys, too. If a chimney is entirely made of metal, it doesn’t need to be repointed since there’s no mortar to replace. However, some chimneys have metal caps built into brick or stone bases that may require repointing.
