How to Repair a Brick Chimney
Masonry fireplaces, whether wood-burning or gas, are cozy features that represent the epitome of home for several owners. Yet cracks during a brick or within the masonry joints between bricks are early warning signs that your chimney is on the road to ruin. Patching cracks in your brick chimney can prevent thousands of dollars worth of repairs afterward, also keep you and your family safe by reducing the likelihood of chimney fires.
Small cracks within the summer can become surprisingly large cracks by next spring. Letting those larger cracks within the outer brick go unattended will deepen the penetrating effect of rain, snow, and ice. Then, the water begins to figure its way down, sometimes between the outer brick and therefore the flashing, sometimes farther inside, between the outer brick and therefore the flue.
Left unchecked, these tiny events can accumulate and end in disaster for roof systems and interior ceilings, insulation, wall studs, and even floors.
Repair Cracks to stop Chimney Fires
Even worse, cracks during a brick chimney that continue from the flue to the outside are one cause behind a terrifying, devastating phenomenon: a chimney fire. Chimney fires can ignite instantly — those who have experienced them describe it as an explosion followed by a sound almost like a rattler. Once a chimney fire has started, only the hearth department can stop it since it must be extinguished from the top-down.
The good news is that cracks in chimney brick, mortar, crown, and cap are very easy for a do-it-yourselfer to repair with only a couple of simple tools and materials. Pick a warm, dry day for this project, as a number of the materials need a couple of hours of curing time.
In most communities, minor brick chimney repair that doesn’t involve replacing any elements of the chimney shouldn’t require a permit. If you’re removing and replacing bricks in your chimney, ask your local permitting office. In some areas, this type of labor requires that you simply apply for a permit and have the work inspected once you complete it.
Brick chimney repair depends on seasons and weather. don’t apply mortar when temperatures are below 40 degrees Fahrenheit. If you’re applying the mortar in warm weather but expect temperatures to drop below freezing within 24 hours, don’t apply the mortar. Instead, wait until the temperatures are favorable.
Roof Safety
Any time you’re performing on a roof there’s the potential for falls and high injury, and therefore the higher the roof or the steeper the pitch of the roof, the greater the danger is going to be. If you select to try your own chimney repair, confirm to figure on a dry day, and to wear shoes or boots with firm-grip soles. Never work on a roof that’s damp. A mild, dry day is right for performing on a roof.
Consider using a security harness, also called a fall-arresting harness, whenever performing on a roof — especially if the roof is extremely steep or very high. The equipment includes a metal ridge anchor that’s attached to the height of the house, a body harness that matches around your back and hips, and a rope with an automatic locking mechanism that forestalls you from falling an extended distance. Fall-arresting harnesses are often rented reception improvement centers and gear rental outlets.
Work slowly and punctiliously when making chimney repairs. Impatience and hurried work invite accidents.
What you will need
Equipment/Tools
- Joint raker
- Tuckpointing tool
- Ladder
- Masonry chisel
- Hammer
- Pointing trowel
- Wire brush
- Putty knife
- Garden hose
- Caulk gun
- Paintbrush
- Safety glasses
- Fall-arresting harness (optional)
Materials
- High heat mortar
- Latex gloves
- Mortar
- Clean rags
- Water-based silane/siloxane water repellent like Prosoco Sure Klean
Instructions
Not all repair projects would require you to finish all the subsequent steps. Minor chimney damage may require only cursory work. But it’s an honest idea to look at the chimney carefully and complete whatever work is named for.
01 Repoint the Chimney Brick Mortar
Mortar holds bricks together. New mortar is smooth and solid, but because the seasons pass, the weather batter the mortar, causing it to crumble. Since mortar is softer than brick, the mortar will always deteriorate first. Repointing, or tuckpointing, is that the process of scraping out the crumbly mortar and replacing it with new mortar.
Use a joint raker to scrape out loose, weak mortar, leaving the great mortar in situ. For harder crumbly mortar, gently tap it out with a hammer and masonry chisel. With a wire brush, sweep out all remaining bits of mortar.
Spray down the brick with the hose, and let it sit for half-hour. confirm the roof is dry before you continue work.
Mix up a batch of mortar until it’s the consistency of stiff spread. With a trowel, press the mortar into the open joints in order that it matches the design of the prevailing mortar. Smooth down the joints with a tuckpointing tool. The joint should be slightly concave, recessed in from the surface of the brick.
02 Caulk around the Flue and therefore the Crown
One major avenue for water to enter your home and cause damage is at the joint between the chimney flue and therefore the crown — the concrete cap that covers the highest of the chimney brick. Typically, gaps form during this area after several seasons. Water that enters this gap can flow all the way down the edges of the flue.
With a wire brush, clean out any debris like moss and loose mortar. Use a caulk gun and a tube of high-heat mortar to fill this gap with an entire bead of caulk.
03 Patch Cracks within the Large Crown Area
The chimney crown may be a sloping cap that forms the top-most section of your chimney. Its purpose is both to guard the masonry section of the chimney and to stop water from pooling on top. Cracks within the crown are even more problematic than cracks on the vertical sections of the chimney, since water, snow, and ice can gather there.
Large cracks on the chimney crown between 1/8 and 1 inch in diameter are often repaired with pre-mixed cement patch or mortar. Inject the repair mix into the crack with a squeeze bottle, or force into the crack with a spatula. Curing time typically ranges from four to 6 hours, but it’s going to take longer for wider cracks.
04 Patch Hairline Cracks With Sealant
Hairline cracks, sometimes called spider cracks, are treated differently from large cracks since mineral particles within the patch or mortar are overly large to suit the hairline crack’s narrow space. The answer is to use a water repellent that’s highly liquid in consistency, which may penetrate the hairline cracks. As a bonus, this sort of product will seal up all other areas of the porous crown, preventing additional hairline cracks from forming.
Use the corner of the spatula to scrape away any loose particles but don’t enlarge the crack. Apply the water repellent undiluted with a brush. One gallon is going to be adequate for 2 coats on an average-sized chimney crown.
05 Repair Cracked Bricks
Individual chimney bricks have some cracks or two that are often repaired with a high-heat mortar and a pitch gun.
Clean out the crack with the sting of a spatula or with a screwdriver. Sweep the crack clean with a wire brush. Squeeze the high-speed mortar into the crack as far as possible. Generally, the mortar won’t extend very far unless it’s an outsized crack. With a gloved finger, clean the mortar from cracks. Use a rag to wash the world around the crack.
If the brick cracks are very thin hairline cracks, you’ll be ready to close them up by brushing them with water repellent.
06 Replace Cracked Bricks
Severely damaged bricks should be entirely removed and replaced. It’s possible to carefully remove one brick without affecting adjacent bricks.
With a masony chisel or old flat-head screwdriver, slowly chip away at mortar from between the bricks. Employing a drill and masonry bit to bore holes into the mortar will speed up the method and permit you to succeed farther back.
Once the brick is loose, bring it by hand and pull it. Use the chisel to chip away at residual mortar from the adjacent bricks in order that they’re smooth.
Use a little trowel to butter all four sides of the replacement brick (not including the front or back) with mortar. Push the replacement brick up place, centering it in order that the seams on all sides are of equal width.
