Chimney Problem: Call a Sweep or a Roofer?

The flue is the passage the smoke travels up. A sweep cleans it with brushes, clears soot, nests and fallen debris, and can check that the smoke path is open. If your fire smokes into the room, the stove is hard to light or there is soot on the hearth, the cause is usually inside the flue, and a sweep is the first call.

Many sweeps also carry a camera that runs up the flue and shows a cracked liner, a blockage or a gap. That is worth having before any roof work, because a flue that is damaged inside cannot be cured from outside. If a gas fire is the reason for your question, our guide to a chimney liner for a gas fire covers when a liner comes into the picture.

A sweep does not work on the roof structure. A cleaned flue will not stop a damp patch on the chimney breast or a drip into the bedroom, and a roofer cannot clear soot from where they cannot see. The two jobs sit side by side, and it helps to know which side your symptom belongs to.

The stack is the brick structure that rises through and above the roof. It carries the pots, the short pipes of clay or concrete along its top edge, and it is weatherproofed by the flashing, a lead strip at the point where brick meets tile, and the flaunching, the sloping mortar bed that holds each pot in place. A roofer looks after all of this.

Typical signs that call for a roofer are brown stains on the ceiling around the chimney breast, mortar falling into the garden, a pot that has moved or cracked, bricks with faces flaking off, and a stack that leans. Repointing, flashing renewal, flaunching repair and rebuilds are all roofing work. Our page on chimney flaunching repair shows what that bed does and why it fails.

Roofers also fit caps and cowls on stacks that are no longer used, and ensure a closed-off flue is still ventilated. If the work involves taking down brickwork or lifting pots, the roofer arranges safe access, whether that means ladders, a tower or full scaffold, depending on the stack.

Damp on a chimney breast can have several causes. Rain getting past the flashing or the flaunching is one, and a sweep cannot help with that. Condensation inside a flue left idle is another, and so is soot or tar staining through the plaster from a flue in poor condition. Looking at the stain does not settle it.

Rain-only symptoms point to the roof. If the stain appears or grows after heavy rain and dries in settled weather, ask a roofer to check the lead, the mortar bed and the pots. If it appears when the fire has been lit, or has a brown, tarry look, speak to a sweep or a flue specialist first. Our post on how to trace a chimney leak explains the clues in more detail.

Birds are another overlap. A nest in the pot can block the flue and cause smoke to come back, and the law protects wild birds' nests that are being built or used, so removal needs care and timing. Ask whoever you call how they handle it before they start.

A simple rule works for most homes. If the symptom happens inside, around the fire, the smoke or the soot, ring a sweep. If it happens around the stack, the ceiling or the garden, ring a roofer. If you cannot tell, start with whoever can look at it soonest and ask them to say plainly what falls outside their trade.

Before a roofer visits, photograph the stack from the garden, take a second picture of any ceiling or breast stains and jot down when they show up. Mention if the chimney is in use, capped or shared with next door. This lets us plan the access and decide whether a flue check should come first.

A roofer who also sees a possible flue fault should say so and suggest a sweep or specialist, not guess. We examine the outside of the stack and the roof around it, send you pictures of your own chimney and put one total price in writing. If the job turns out to need a flue specialist as well, we tell you before any work begins. Our chimney repairs page lists the jobs a roofer covers.