How Do You Repair A Chimney?

red brick chimney on a housetop

Should You Repair an Unused Chimney?

“Ho Ho Ho! Who’s up on the rooftop?! Down through the chimney came Old Saint Nick …”. Along with ashes, soot, birds’ nest, and other debris, maybe even some bricks and mortar. If you’ve noticed some missing mortar or have had a few bricks fall into the fireplace, it is time for chimney repair

Maybe you don’t use your fireplace and you’re wondering “Why do I need to repair my chimney?” Much like the water heater, the chimney is taken for granted. It is there, it does what it is supposed to. It is part of the house that is worry-free, or so we’d like to think it is. Surprisingly, like a water heater, a chimney does have problems and needs chimney repair, the sooner the better.  Why?  

Why Do You Need Chimney Repair?

Well, if you do use the fireplace, a damaged chimney is a fire hazard. If you don’t use your fireplace, the chimney and the fireplace connected to it are structural parts of your home. If they are weak, so is the wall around the fireplace and the roof supporting the chimney. If you’re not sure that your chimney has issues, here are 7 indicators that chimney repairs are needed: 

  • Efflorescence 

The white discoloration on the chimney is called efflorescence and is fairly easy to remove. However, cleaning and removing the efflorescence doesn’t mean the cause of it is gone. The cause is excess moisture within the masonry and if it isn’t addressed, the chimney will deteriorate without chimney repairs done.

  • Rust

If there is rust on the damper or firebox, it is another indication the chimney has excess moisture. If the damper has rust on it, then it probably isn’t operating right or sealing properly either. If you can see the rust, the flue tiles are probably cracked too. A professional chimney sweep can inspect your chimney flue lining with a special camera to make sure the chimney system doesn’t have a breach. If there is a breach, they can do a chimney repair and make your home safer from possible fire hazards.

  • Deteriorating 

If the mortar joints on the chimney are deteriorating, chimney repair is needed pronto!  This deterioration is exposing the chimney to moisture and accelerating more deterioration of the chimney.  In the far north, like here in Rhode Island and New York, the freezing winter temperatures freeze inside those cracks, then as it thaws, it makes the cracks bigger. Eventually, probably faster than you may think, your chimney could collapse.

  • Shaling

The flue on your chimney is what keeps the fireplace safe to use. When you see thin slices of the chimney tile inside the fireplace, the flue is not doing its job. This is one of the main reasons for annual professional chimney inspection is recommended. A professional chimney sweep will inspect and analyze the entire chimney, with a focus on the flue lining. If they spot any problems, they will advise what chimney repairs are needed and proceed, keeping your chimney safe from any safety breach. 

  • Spalling

If you’re finding bits and pieces of masonry around the exterior of your chimney, this is called spalling. This happens moisture enters the masonry and forces the surface of the brick, concrete, or stone to flake, peel, or pop out. Chimney repair or replacing this damaged masonry is essential in preventing the continued crumbling and destruction of your chimney.

  • Wallpaper

When you notice the wallpaper around and near the chimney has water stains, you probably have chimney damage too. This could be a roof issue, or it could be you need chimney repair because of moisture getting around or in through the flue or other areas of the chimney. 

  • Crown 

This is where hiring a professional chimney sweep is recommended because it requires getting on the rooftop to check.  The chimney crown is an important part of the structure and provides a line of defense from the elements. A cracked chimney crown allows moisture to seep in, and create larger cracks and water around the flue lining. This all leads to other issues we’ve listed her like shaling and spalling.

How do you repair a brick chimney, and what do you use to repair a chimney?

For minor chimney repairs, in most areas, a permit isn’t required. If any bricks have to be removed/replaced, you may need to inquire about a permit and municipal inspection of the finished work. 

The first thing you need to know about how to repair chimney mortar is to watch the weather. Brick chimney repair requiring mortar should never be done when the temperature is below 40 degrees Fahrenheit. If you have a warm day to do the work, make sure the temperature isn’t expected to drop to or below freezing within the next 24 hours. The following are possible repair steps your chimney repair may need: 

  1. Repoint the Brick Mortar

The mortar is the stuff you see between the bricks and holds them together. As seasons come and go, the mortar is battered by the elements and will often begin to crumble and deteriorate. Repointing is necessary to replace the mortar and keep the bricks stable. 

Using a joint raker, scrape any loose and weak mortar. Then with a wire brush, sweep the remaining bits out. With the garden house, spray down the brick and let it dry for 30 minutes. 

While that is drying, mix a batch of mortar up to a stiff peanut butter consistency. Using a pointing trowel, press the mortar in the open joints, getting it so that it matches the existing mortar. With the tuckpointing tool, smooth the joints so that they are concaved and recessed slightly from the brick’s surface.

  1. Caulk the Crown and Flue

The area between the chimney and the flue is a key area that water enters when the joint is not closed and sealed with the crown. The crown is the concrete cap covering the chimney top and typically will have a gap after a few years. That gap allows water inside the chimney flue and into your fireplace. 

Using a wire brush, clean and remove any loose debris like mortar and moss. Then with a caulk gun loaded with high-heat mortar, fill the gap by creating a bead of the caulk.

  1. Large Crown Area Patching

The chimney crown is the top section of the chimney, and it protects the masonry section of the chimney. The sloped shape prevents water from pooling, so when there are cracks in the crown, it can be problematic. This is where ice, snow, and water hit first and can gather if the cap isn’t in good condition. 

Any cracks in a diameter size between 1/8 and 1 inch can be repaired with a pre-mixed cement patch or mortar. Simply inject the mix into the crack using a squeeze bottle and allow it to cure up a minimum of 4 hours, again, this requires planning with the weather!  

  1. Hairline Crack Patching

Hairline cracks can be treated differently than the large cracks we’ve mentioned. Using a high liquid consistency masonry sealer after clearing any loose particles with a putty knife, using a paintbrush, apply the sealer. Two coats are recommended, allowing the first one to completely dry and cure first.

  1. Repair Cracked Bricks

Using a high-heat mortar, you can repair small cracks in one or two individual chimney bricks with a caulk gun. Clean the crack first using a putty knife then sweep it out with a wire brush. Next, squeeze the high-heat mortar into the crack, and with gloves on or using a rag, wipe any excess mortar from the crack.

  1. Replace Cracked Bricks

If there are severely damaged bricks, they need to be removed and replaced. Removing one brick at a time will not affect the adjacent bricks.

Using a masonry chisel slowly chip away the mortar between the bricks. Then bore holes into the mortar using a masonry bit with your drill. Now slowly pull the loosened brick and chisel out any remaining mortar until you have a smooth surface.

With a small trowel, apply the mortar-like butter on bread to all four sides of the new brick, leaving the front or back clean. Push it in place and center it so that you have equal seams on all sides. Using the tuckpointing tool, remove any excess mortar as you smooth the joints.        

How do you repair the inside of a chimney?

Creosote is what builds up inside the chimney, obstructing the flue. When the flue becomes obstructed too much, it can cause exposure to carbon monoxide or even cause a fire inside the house. The best thing you can do is hire a professional chimney sweeper to clean and inspect the chimney and fireplace. The Chimney Safety Institute of America recommends having this done annually just before winter. While the chimney sweep is inspecting and cleaning, they can do any chimney repairs needed inside the chimney too.  

How do you repair a concrete crown on a chimney?

Once you have your ladder securely in place and have safety equipment engaged, chimney repair to the crown is fairly basic: 

  • Small crown cracks: Fill with an acrylic or silicone caulk using a caulk gun and a gloved finger.
  • Cracks that are 1/8” to 1/4” wide using your gloved finger and a stiff paintbrush work the patching material into the large cracks and smooth over the top. 
  • After 15 minutes, brush a liquid seal coating over the entire crown, especially around the inner edges and  outer edges where the crown is joined to the chimney flue. 

Can a roofer repair a chimney?

You should not rely on a professional roofing contractor for chimney repair jobs. A professional roofing contractor will decline to do any chimney repairs and recommend that a professional chimney sweep be contacted.

How much does it cost to repair a cracked chimney?

Professional chimney repairs can vary based on the type and amount of damage. With a masonry chimney, the joints contract and expand with the temperature and cause cracks. Because those cracks will allow carbon monoxide into your home, along with possible embers, the cost of chimney repairs can be a lifesaving expense. 

The average range of professional chimney repairs can start around $200 and reach up to $3,000. In addition to the amount and type of damage, the height of the house will factor into the cost too. 

red brick chimney

In Closing 

With chimney repair expenses possibly getting into the thousands of dollars, a homeowner will want to know if chimney repair is covered under homeowners’ insurance. After all, owning and maintaining a home is expensive enough, if the monthly premium of your homeowners can help with the expense, that would be helpful, right? 

Sadly, the basic aging, wear and tear of a chimney, and repairs are not covered by homeowner’s insurance. If the chimney is damaged by a sudden and unexpected weather event, the chimney repairs would be covered.