Why Is the Base of My Chimney Crumbling?

Category: Chimney

Chimneys have long been considered a core element of the traditional American house. Every chimney will deteriorate with time if not properly maintained. There may be issues with components such as the chimney cap or liner, but these are often simple to fix. This guide will help you find out the reason for your crumbling chimney. Let's get started.

Signs of Chimney Crumbling

Following are the signs of a leaky chimney - Cracked bricks - Foul odors from the fireplace - Damp areas on the ceiling near the fireplace - Internal chimney masonry damage - Discoloration on the exterior masonry

Reasons Why Your Chimney is Crumbling

Several reasons can cause chimney damage. They include:

Water Infiltration

Water penetration is one of the leading causes of deteriorated and crumbling chimney masonry. If your chimney has minor cracks, the water can get in, freeze, and expand as the temperature drops. This will result in more damage and initiate a cycle that may lead to significant structural and safety hazards. water damage to a chimney In addition, water may enter cracks in the cement chimney crown and destroy it, causing damage to the bricks covered by the crown. Water can also cause damage via dislodged or missing roof flashing.


When the surface of a brick breaks off or gets damaged, this is referred to as "spalling." Bricks absorb moisture due to the substance they are made of. The water absorbed within each brick freezes and thaws when temperatures vary over the winter, resulting in spalling. Spalling is more than just an aesthetic problem. Bricks may become unusable as structural components if broken to the point that they no longer provide support. You should check for external damage to your chimney, such as cracked bricks around the chimney base.

Liner Damage

If water gets into the chimney, it might rust the damper or the firebox. When there is plenty of moisture to cause rusting, a comprehensive chimney examination should be performed to evaluate the extent of the water damage since not all damage is immediately evident. Another issue that moisture might create is tile liner degradation. If there is a gap in the flue, it must be fixed as soon as possible; however, if moisture penetrates the gaps, it may cause damage to the ceilings and walls. chimney liner installation Water may enter the chimney and fireplace for several reasons. The lack of a chimney cap is a primary cause of moisture in the chimney. Rainwater, leaves, and other waste may enter the chimney without a cover. If your chimney cap is installed, make sure it is installed correctly, or else it will not be able to prevent moisture.

Weak Footing

The chimney footing may sometimes be too thin or not sunk deep enough, causing it to crack/crumble under the substantial weight of the piled brick and mortar. Footings made of inferior materials are more prone to failure. A cracked footing is a common cause of chimney tilting. Generally, the footing should be at least one foot thick and extend six inches beyond the chimney on all sides.

Weak Foundation

A sinking foundation may generate a leaning or tilting chimney. The ground surrounding your house may shift and alter continually, weakening your foundation. Soil may become weak and saturated with water when the circumstances vary from season to season. The continual movement of the soil might weaken it over time, putting your foundation at risk. When a foundation begins to shift, your chimney may lean or tilt inward or outward away from your house. Even if your chimney is not leaning much, you should inspect it for cracks or gaps between the chimney and the siding. Water and insects will enter through these openings, causing more damage to your property. Keep an eye out for crumbling mortar as well.

Damaged Mortar

Repeated freezing and thawing cycles may damage the mortar between the bricks on the chimney. Damaged mortar causes brick degradation, including cracks. Fresh mortar may be used to repair moisture-damaged mortar. The technique of tuck-pointing can be effective. The method involves removing and replacing broken bricks. Tuck-pointing is an effective option since it blends the repaired area in with portions that do not need care. In addition to minimizing the need for expensive future repairs, the technique guarantees that the joints between the bricks are sturdy and water-resistant.

Damaged Chimney Flashing

The flashing is the metal covering that joins the chimney to the roof. It acts as an additional layer of moisture protection. However, it will not endure forever and will most likely deteriorate with time. As a result, you must inspect the flashing regularly for cracks, corrosion, and general wear and tear. While it is feasible to repair minor damage to the flashing, it is preferable to replace it entirely.


A powerful lightning strike may induce brick spalling inside your chimney construction. In addition, direct lightning can damage brick and mortar or metal components like chimney liners. Lightning can also produce heat to ignite creosote, and chimneys can catch fire. If your chimney catches fire due to lightning, it is recommended to call a service professional who can fix the problem before serious damage.

House Settling

Cracking in chimney bricks and mortar may be caused by the natural settling of homes over time, especially if the chimney was constructed poorly.

Salvaged Bricks

Weak bricks and mortar compounds are used in the construction of faulty chimneys. Salvaged bricks, for example, have a reputation for having shorter lifespans and falling to deterioration sooner than high-quality bricks.

Dangers of Damaged Chimney

Chimney masonry deterioration may result in a variety of undesirable outcomes. Most of the time, spalling bricks enable water into the chimney system, causing more vulnerability and potential damage to the chimney liner, fireplace damper, and neighboring property components such as ceilings, walls, and beams. This water damage sometimes goes unnoticed until there is a major health or safety danger. This is particularly true for mold breakouts behind walls and in mostly closed-off attics. Brick spalling may lead to a collapsed chimney in addition to repairable structural damage to the chimney and its components, as well as the home itself. Parts of the roof and things in the yard under the chimney may be damaged if this occurs. During a chimney collapse, people and pets might be badly wounded. A damaged chimney can also become a fire hazard when exposed to lightning and cause carbon monoxide poisoning.

Maintenance is Important

Keeping an eye on the condition of your chimney is crucial, but waterproofing may go a long way toward preventing damage. Make an appointment with a chimney specialist to apply a waterproofing solution designed exclusively for chimneys. As a result, your chimney will have an extra layer of moisture protection. A waterproof sealer is often applied to the brickwork and chimney crown as part of chimney repair procedures. If the damage is minor and all you need to do is keep additional water out. Tuck-pointing, as mentioned earlier, is the technique of adding fresh, new mortar to faulty areas. Individual bricks may typically be replaced if they are broken or loose. When a chimney is significantly damaged, partial or total rebuilding is required. Chimney rebuilds should never be undertaken by a beginner or a "handyman" but only by a qualified, licensed chimney specialist. Since 1985, we’ve helped thousands of homeowners with creosote cleaning and chimney maintenance. That’s why we are the most trusted chimney maintenance company in the Midwest. Contact us to speak to a specialist!

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