If your roof is leaking around the chimney, the most likely culprit is failed, deteriorated, or poorly installed flashing. The thin strips of metal that seal the junction between your chimney and the surrounding roof. This is one of the most common roof leak repair jobs in Melbourne, and the good news is that it rarely requires a full roof replacement to fix. In most cases, targeted flashing repair or replacement restores a fully watertight seal at a fraction of the cost of broader roofing work.
Here's everything you need to know about why our roof is leaking around your chimney.
Chimney flashing is the metal system that seals the gap between your chimney and roof. It's made up of several interlocking pieces, such as step flashing, apron flashing, counter flashing, and a saddle behind larger chimneys. When any part fails through rust, lifting, cracked sealant, or loose mortar, water gets in. This is the most common cause of chimney leaks, and it's almost always repairable with the right tradesperson.
Your chimney sits fully exposed above the roofline, taking the full force of Melbourne's weather year after year. Over time, the mortar between bricks cracks and crumbles, creating gaps that let water straight into the masonry stack. This moisture then travels down inside the chimney and often shows up as damp patches on walls or ceilings well below the roof.
A chimney saddle or cricket is a small, peaked structure built behind the chimney to divert rainwater around both sides. For chimneys wider than 750mm, it's considered best practice. Without one, water running down the roof slope has nowhere to go except straight into the uphill flashing joint. During heavy rain, that's a significant amount of water pressing against an already vulnerable point.
Not every chimney moisture problem comes from rain. Gas appliances produce moisture in their flue gases, and if your chimney is unlined or poorly sealed, that condensation builds up and migrates into the surrounding structure. The tricky part: it looks exactly like a flashing leak from inside the home. The fix, however, is completely different, which is why proper diagnosis before any repair is essential.
Tiles sitting beside a chimney are cut to fit around the masonry, meaning more joints, more cut edges, and more weak points than a standard full tile. These tiles can crack under foot traffic, lift if their bedding deteriorates, or shift in a storm.
A previous repair done cheaply or incorrectly can set up the conditions for your next leak. Common shortcuts include applying sealant over corroded flashing instead of replacing it, flashing lapped the wrong way so water runs underneath it, or gaps filled with expanding foam rather than properly fixed. These quick fixes might hold for a season or two, but they almost always fail again, and they can make the eventual proper repair more complicated and more expensive.
If the leak is not near the chimney at all, why a roof leaks and the most common causes of roof leaks cover the other places water tends to get in.
The repair process depends on the specific cause, which is why diagnosis always comes before any repair recommendation. Here's how a proper roof leak repair around a chimney is carried out:
A licensed roof plumber inspects the chimney flashing system, the surrounding tile or metal courses, the chimney mortar and brickwork, and the interior from the roof cavity if accessible.
If the flashing is the cause, the repair involves either targeted flashing repair or full flashing replacement for widespread deterioration or incorrect original installation.
Flashing repair typically involves re-bedding lifted sections, replacing corroded individual pieces, re-embedding counter flashing into freshly raked mortar joints, and resealing joints with appropriate weatherproof compound.
Full flashing replacement strips out the existing flashing system entirely and installs new step, apron, and counter flashing using appropriate materials.
If mortar deterioration is contributing to the leak, either as the primary cause or as a secondary factor alongside flashing failure, the exposed mortar joints on the chimney exterior are raked out and repointed with fresh mortar. This stops water from entering the masonry stack and extends the structural life of the chimney itself.
Any cracked, displaced, or incorrectly cut tiles adjacent to the chimney are replaced with colour-matched alternatives. The bedding and pointing of the ridge capping immediately at and around the chimney is inspected and renewed if it's deteriorated.
Before the job is called done, the full chimney area, where flashing, surrounding tiles, mortar, and visible interior from the roof cavity where accessible is re-inspected to confirm the repair is complete, and no secondary leak points have been missed.
My Plumbing Services is the trusted roof repair and replacement servicing across Melbourne, whether you need a scheduled inspection and fixed-price quote, or an honest assessment of whether repair or re-roofing services are the right call for your property.
Contact a licensed roof repair plumber or request a quote online from My Plumbing Services.
