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Chimney repair is a routine part of home maintenance that is often overlooked. If homeowners stay on top of their upkeep, overall repair costs can be reduced.
This page is a resource to help homeowners develop a better understanding of chimney repair and maintenance. A well-informed homeowner is able to make better decisions for their property.
1. Repointing/Mortar Restoration
Mortar restoration is generally the first level of maintenance. Mortar is usually softer than brick or stone, and will often deteriorate or crack first.
Repointing can prevent further damage to brick or stone, and extend the life of the chimney. If water finds its way through damaged mortar joints, the chimney will deteriorate at a much faster rate.
The most severe damage is often associated with freeze/thaw cycles in cold weather locations. Moisture in freezing temperatures can damage brick or stone, due to the expansion of water when frozen.
When repair work is completed, custom colored mortar should be used, to ensure the new mortar matches the original.
2. Brick Replacement
If a chimney has a number of cracked brick, but not enough to warrant a rebuild, the damaged sections should be replaced. This will extend the life of other brick or stonework, and prevent the need for a full rebuild.
Damaged brick are carefully removed to ensure that the intact ones remain in good condition. Once they are removed, new matching brick are installed in their place.
An experienced mason will search multiple brickyards, if required, to get the best possible match for the
homeowner. If this step is not executed with care, the repairs could stand out rather than blend in with the existing masonry.
3. Chimney Rebuild
The final and most thorough level of repair is a rebuild. At this level, the majority of brick are cracked or have significant spalling. Damage will only continue to compound, and you could potentially risk water leaking into your home.
When deconstructing a chimney, the concrete cap is broken up and removed, along with all
the brick. Chimneys are usually rebuilt from the flashing up, but sometimes only the top section needs repair.
The chimney is rebuilt using new brick and mortar to match the original as close as possible. During the rebuild, flues are replaced as required and a new concrete cap is installed to complete to project.
With a full rebuild, you have the benefit of a brand new chimney which will be maintenance free for many years.
Chimney Cap Repair
In a masonry context, the term cap refers to the concrete cap that sits on top of a chimney. Outside of masonry, a cap often refers to the metal rain cover that sits on top of the flue or liner. Both of these serve completely different purposes.
Used to protect the brick or stone chimney, from weather conditions.
Metal Rain Cap
Used to prevent rain, or varmints, from entering the liner.
It is important for a chimney to have a proper concrete cap to protect it against the elements. A well-made cap will consist of a reinforced, pitched, concrete slab, that overhangs the sides of your chimney by about two inches. This will protect the chimney from weather, and redirect any water away from it. Click here for more information on chimney caps.
A properly installed cap can easily last upwards of 2 decades, but will eventually need to be replaced. One of the factors that determines how long they will last, is the weather conditions near the property.
Concrete caps should be replaced before cracks develop large enough to let in water. Caulking a crack is a quick fix, but is not advised long term. If the caulk were to fail, water would be let in causing more damage.
The principle function of a chimney liner is to vent fireplace/home appliance byproduct through the chimney. Without a liner, chimneys would be less efficient, and require more maintenance. Two common types of liners found in most homes today are clay flue and metal/stainless steel.
Clay Flue Liner
Flues are resistant to extremely high temperatures, and have very low moisture absorption, thus allowing them to outlast most other parts of a chimney. During Repair work, it is common for only the top flue section to need replacement. This is due to the weather exposure they receive sticking outside the chimney cap. Clay flues come in numerous sizes, with the most common widths being 8×8”, 8×12”, and 12×12”.
Metal liners are required by a variety of home appliances. Aluminum is a more affordable option, but can only be used for gas burning appliances with lower flue temperatures. When a high heat source is being used, such as a woodburning stove, a stainless steel liner may be required. Metal liners are also a great option when an original clay flue is damaged. It is more efficient to install a stainless steel liner, rather than replace the original.
Flashing is a custom fabricated piece of metal, that seals the chimney at the roof line. This product is made from a variety of metals, but galvanized steel is the most common. If the flashing develops holes, it should be replaced rather than being sealed with caulk or tar.
Leaks should be addressed quickly to prevent damage to the property. A surprisingly large amount of water can come through a very small hole in the right conditions.
If a chimney is in bad shape, water could potentially be coming in from any one of the deteriorated areas. In this case, the obvious solution is to repair or rebuild the chimney. If there is no need of apparent maintenance on the brick or cap, the flashing is a very common place for leaks. All caulk should be inspected and reapplied as required.