A lot of UK homes have non-working chimneys. In older properties, the chimney breast in the house might have been removed to create more room space, or the fireplace has been converted into a TV area, loveseat, library… Although fires are no longer lit in the fireplace, the chimney will still be a characteristic of the original roof.

If not properly maintained, a leaking chimney can allow water to seep into the home damaging the loft space, ceiling and the chimney itself. If the chimney leak has been left unattended for a while, the leaks could damage the roof beams, joists and wooden structure through wood rot.

What is the most common cause of chimney deterioration?

Even with on-going maintenance to a chimney, a chimney being exposed to all weather conditions from harsh UV rays to snow and hail in the UK, may only last 30-50 years. The biggest cause for deterioration is the bricks and mortar joints. Weather will affect the chimney from all directions, so the decline of a chimney's strength and water resistance is inevitable with the weather conditions being the number one cause to slowly corrode a chimney.

Any falling debris, either from a tall tree in close proximity to the roof, a freak weather storm flying debris around, or debris falling from the crumbling of the chimney flue could cause damage to the chimney.

Can a brick chimney be fixed?

If the chimney has crumbling bricks or a damaged cracked brick, this is an easy repair for a roofer. They will be able to slide out the damaged bricks and replace them with new bric, re-doing the mortar, sealing in the new bricks but they may feel it best to repoint the entire chimney to ensure all the brickwork is protected from rain and visually pleasing. Rather than having a section of new mortar that looks vastly different from the rest of the chimney.

Another fix on a bricked chimney might be to remove the crumbing cement chimney crown and recement the chimney crown. This will leave the chimney weather protected.

The flashing around the chimney, at the base of the brickwork joining the shingles,  might be letting water through, this would need the old flashing to be removed and new flashing laid around the chimney.

How much will it cost to repair a chimney?

The cost of a chimney repair will greatly depend on access to the chimney, how steep the pitch of the roof is, whether the roofer will have access with or without the need for scaffolding and how big a repair job is needed on the chimney. (The last thing a roofer needs is to fall down the chimney!)

Repointing a chimney will involve two days of labour whereas repairing flashing might only be a couple of hours to a day depending on the amount of flashing or leadwork needing repairing. Re-cementing a crown on the chimney could be done in a day. Of course if the repair work on the chimney is a big job, involving all key elements of the chimney, this might involve an entire week of roofing work.

If scaffolding is needed, this will eat into labour time for the roofer setting up their access on to the roof to reach the chimney safely.

How do I know where my chimney leak is coming from?

An experienced roofer will be able to inspect the chimney and from a visual inspection, work out the area causing the chimney leak.

The most vulnerable chimney area is the brick and mortar joints which over time will be damaged by constant weather changes. Over the years, the mortar joints will crack, allowing water to seep in. If the roofer notes that the mortar joints are still in good condition, this will lead the roofer to investigate the flashing around the chimney.

If the flashing is cracked, brittle or showing signs of sealant missing or eroded, this will be the culprit for water ingress. If the flashing or leadwork appears in good condition, the next part of the chimney to inspect is the chimney crown.

The crown, also known as a chase cover, cap or damper, protects the chimney from rain, snow and hail entering. Without a chimney cover, birds might try to nest in the chimney, further damaging the chimney.

If the chimney is old, it may be a case of all three areas deteriorating allowing water or moisture to seep in and leak, meaning the roofer will need to repair the entire chimney from repointing brickwork, to recementing a crown and redoing the flashing around the chimney.

When to repoint a chimney?

There is no set time frame on when a chimney might need repoint. Chimney repointing is repairing the cement mortar between the bricks in a chimney stack. Repointing means scraping out the old mortar, and filling the gaps between the bricks with new fresh mortar, which not only gives the chimney a better appearance but more importantly protects the chimney and keeps it waterproof. 

The brickwork on the chimney can withstand the elements for a hundred years or more, but the mortar joints are more susceptible to erosion from the elements. A chimney will need repointing when showing visible signs of deterioration around the mortar.

This might not be noticed from the ground, but instead you might be aware of pieces of mortar or brick that have fallen to the ground from the chimney or worse, noticing some water damage inside your home or loft space. If you have any cause for concern, call in a professional roofer ASAP to inspect the condition of your chimney and while doing that they can inspect the rest of your roof as well.

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