Signs your chimney needs repair

Whether your chimney is functional or not, it is a structural part of your roof that will require maintenance at some point. Since brickwork/ stonework and associated fixings such as mortar are not immune to weathering and movement, it’s also important to get your chimney checked by a professional now and again to make sure it’s structurally sound.

Does my chimney need repair?

It isn’t possible to know if a chimney needs repairing without physically inspecting it. Since it’s right up there on the roof, only a competent person should attempt this for safety reasons. A physical inspection will reveal what, if any, repairs are needed. The good news is most issues only total a few hundred pounds to put right.

Below, we will reveal the common signs that a chimney needs repair. These can be established through a physical inspection:

Leaky roof

If you have a leaky roof, there’s a chance it may be caused by a dodgy chimney. Chimney stacks let water in if the brickwork or mortar is cracked. Gravity causes it to work its way down and that means it can enter the roof area. If you experience a roof leak during driving rainfall (it can appear in the strangest places because of the driving rain), we recommend you get your chimney inspected.

White staining

White staining on a chimney is called efflorescence. It is caused by a crystalline deposit of salts. While efflorescence can be cleaned away, it will return. It’s caused by excess moisture in the masonry. The only way to stop it from developing is to fix the cause of the moisture in the masonry. A physical inspection will likely reveal the issue, which is typically a crack in the masonry somewhere. This can be filled or the masonry replaced.

Damaged mortar joints

Mortar joints join the chimney and masonry together. They are effectively a stone-based glue that also serve as a waterproof barrier. If these are damaged (cracked, split), then water can seep into them. This presents a problem because as the water evaporates, it makes the cracks larger. Eventually, the mortar can lose its strength because of this and a chimney can come tumbling down, literally.

Damp or wet firebox

If you have an active chimney, your firebox is where your fire burns. If the firebox is damp or wet, particularly after rainfall, this is a tell-tale sign there’s something wrong with your chimney or chimney breast. Typically, a damp firebox means moisture is entering the burn chamber somehow. This can be caused by damaged mortar joints, but more commonly by a dodgy chimney stack or chimney pots.

Cracked chimney crown

This is an obvious issue when checked from above. A cracked chimney crown is bad news because it means there’s little protection for the chimney from rain. The main causes of a cracked chimney crown include movement, concrete shrinkage as the water content in the concrete evaporates and freezes and thaws. It’s important to get a cracked chimney crown repaired before the cracks get any larger.

Falling masonry (spalling)

If you see or experience bits of masonry falling from your roof, particularly near the chimney, this can be a sign your chimney needs repair. Cracks in a chimney cause pieces of masonry to fall to earth. These can be the size of dust or half an inch in size. Sometimes, the spalling elements can feel like a powder on your skin when they fall. It’s important to have your chimney and roof inspected if you experience falling masonry.


This is one of the most serious signs your chimney needs repair. Your chimney stack should be straight and true. If you notice one day that it’s off-kilter, and that isn’t normal, your chimney has moved. This is dangerous because it’s typically a sign that the support structure in place has degraded. It is likely your chimney will need rebuilding under the circumstances and we recommend you get it inspected right away.

Never let an issue develop into a larger one!

Lastly, we have an important point. Chimneys are made from stone or brick, fused together with masonry using mortar. Mortar, brick and stone are not invincible. They crack, they split, and they degrade. That’s a fact. If your chimney develops a crack or split in the stonework or mortar, you should get it repaired IMMEDIATELY. Leaving it will only worsen the problem and it’ll potentially cost you a lot more to put right.

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