Chimney stack looking tired? What to check before it gets worse

Of all the parts of a roof, the chimney takes the worst beating. It sticks up above everything else, gets the wind from every direction, takes the rain on the cap, and bears the brunt of frost. Most chimneys we repair have a problem that was small and cheap to fix five years earlier.

What to look for from the ground

You don’t need to get up the roof. Binoculars, or the zoom on your phone, are enough.

The mortar on the chimney pot (flaunching): This is the angled mortar at the top of the chimney, sloping down from the pot to the chimney stack. It should be intact, slightly sloped, and not cracked. If it’s flaking or has pieces missing, water’s getting in around the pot.

The pointing on the chimney stack: The mortar between the bricks of the chimney stack itself. Should be intact, not recessed or missing. If you can see daylight between the bricks in places, it’s repointing time.

The chimney pot: Should be vertical, intact, not cracked or wobbly. Old clay pots sometimes split down the side.

The lead flashing at the base of the chimney: Where the chimney meets the roof slope, there’s usually a step of lead flashing going up the chimney and out onto the tiles. Should be intact, not lifting, not torn.

Anything green growing out of the chimney: Moss, plants, even small trees. Water is getting into the chimney and seeds are germinating. The chimney is wet.

What it means

Each of those signs tells you something:

Failed flaunching = water getting into the chimney stack, usually pooling around the flue. Damages the flue lining and accelerates frost damage to the brickwork.
Failed pointing = water getting into the brickwork. Frost damage follows — water in the bricks freezes, expands, and breaks the brick face off (called “spalling”).
Cracked pot = water getting into the flue. Damages the lining, can allow fumes into the room below if the fireplace is in use.
Failed flashing = water getting into the roof at the chimney junction. The most common cause of a chimney-related roof leak.
Plants growing = significant water ingress, often with structural damage to the upper courses of brickwork.

What’s cheap to fix and what’s not

Cheap to fix:

Repointing the stack — usually a day’s work for two of us, scaffolding permitting
Renewing the flaunching — usually included with repointing
Replacing one or two cracked pots
Re-bedding a loose pot (lifting it off, cleaning, re-setting in fresh mortar)

More expensive to fix:

Full stack rebuild — when the upper courses are damaged beyond repair
Lead flashing renewal — not the materials cost, but the access cost (scaffolding)
Removing and not replacing a redundant chimney — surprisingly involved

Worth doing sooner rather than later:

Repointing before the pointing fails completely
Re-flaunching before the chimney pot starts to wobble
Flashing renewal before water damage spreads to the surrounding roof timbers

The pattern: every chimney problem is cheaper to fix when it’s small. Most emergency chimney work we do is “we should have called you about this years ago.”

What we actually do when we come

For most chimney issues:

Erect scaffolding (or use a cherry picker if access allows)
Inspect from above — the bits you can’t see from the ground
Photograph and write up what we’ve found and what needs doing
Quote in writing — usually a fixed price for the work
Do the work — usually a half-day to two days depending on the scope

For a standard chimney repoint + re-flaunch + flashing check, you’re usually looking at half a day to a day of work. We can usually do it without affecting anything else on the roof.

When the answer is “take it down”

If a chimney is no longer in use (no working fireplace below), and it’s reached the point of needing major repair, the right answer is often to take it down to roof level. This:

Removes the source of the problem
Eliminates the cost of ongoing maintenance
Doesn’t affect the appearance of the house from the ground (a stack at roof level is barely visible)

It’s a bigger job upfront but ends the chimney’s maintenance burden forever. We can talk you through whether it makes sense for your property.

If you’ve spotted something worrying about your chimney, get in touch. Better a small job now than a big job in two years.