The short answer
A chimney sweep cleans the inside of the flue and checks that it draws and is clear. A roofer repairs the outside: pointing, flaunching, flashing, pots and the roof around the stack. If you have smoke, soot or a blocked flue, call a sweep. If you have a leak, damp patch or loose masonry, call a roofer. Sometimes you need both.
What a sweep does
A sweep works inside the chimney. They brush soot and tar from the flue, clear nests and debris, and can check that smoke travels up and out. Some also use cameras to inspect the liner, and a smoke test can show leaks through the flue walls. If you burn wood or coal, regular sweeping reduces the risk of a flue fire and keeps the fire drawing properly.
A sweep may also notice problems higher up, such as a cracked pot, a missing cowl or a flue that looks damaged. But a sweep normally works from the fireplace or the roof edge, and repairing masonry, lead or the cap lies outside the job. When they find something outside the flue, they will usually suggest a roofer.
What a roofer does
A roofer deals with the part of the chimney that meets the weather. That covers the cap, pots, flaunching, brick joints and the brickwork itself, together with the flashing or back gutter where the stack meets the roof. Water enters a stack in these spots, so they are where we look first, and a leak around a chimney is more often a flashing or pointing fault than a flue problem.
Our guide to chimney pots and cowls covers the parts on top, and a pot can be replaced or a cowl fitted on the same visit as any other repair, which saves a second trip up the scaffold. Pots that lean or have cracked bases are common call-outs, and a sweep who finds one will usually pass the job on. A roofer also works at height safely, with scaffolding where needed. MyBuilder's scaffolding guide, updated in August 2026, gives £400 to £900 for chimney-height scaffolding.
Matching the symptom to the trade
Smoke coming back into the room, soot falling into the grate, a fire that will not draw or a smell of damp soot when it rains are flue problems, and a sweep is the first call. A sweep also suits a chimney that has not been used for years, before any fire is lit. Birds' nests, fallen mortar and a build-up of old soot can all block a flue that looks fine from the room, and lighting a fire into that is how smoke ends up in the bedroom or worse.
Brown marks on the wall around the fireplace or on the ceiling, peeling paper, water running down the breast after rain, crumbling bricks or a lean to the stack points to the outside, so call a roofer. Spalled faces and weak mortar are in that group too, and our page on spalling chimney bricks explains the cause. If you cannot tell which it is, start with the roof, since water from outside is the commoner source of damp.
When you need both
Some faults cross the line between the two trades, and the clues are usually mixed. A cracked flue liner can leak fumes into walls, which a sweep may detect and a roofer or builder repairs. A capped, disused flue needs ventilation, and a roofer fits the cap while a sweep clears the flue beforehand. If the breast downstairs has been removed, the stack above can lose its support, and our notes on a removed chimney breast explain what to check.
The order matters more than people expect. Have the roofer repair leaks and masonry first, then a sweep cleans the flue, so debris from the work does not fall into a flue just swept. If you plan to use the fire afterwards, a sweep's certificate gives you something for the insurance file. Our page on how long chimney repairs take helps you plan the sequence.
Cost and what the survey covers
Costs differ: a sweep's visit is a small job, while roof work depends on the stack, its height and how safely it can be reached. Ask each trade what their price includes before you book either. MyBuilder's chimney repair guide, updated in August 2026, puts repointing at around £750, within a range of £500 to £2,000, and flashing repair at £250 to £1,200. These are national typical figures, and your written quote follows a survey.
Our survey looks at everything that is on the roof: the stack, pots, flashing and the slopes beside it. Each one is photographed and the images arrive with your written quote, which shows which faults are roofing jobs and which call for a sweep. Our side is the roof, and if the evidence points inside the flue we say that openly and point you to a sweep.
Getting the right person out first
Describe the symptom when you call, because it sorts the job into the right trade quickly. "Water down the chimney breast after rain" gets the right trade faster than "chimney problem". Send photographs of any stains, the stack from the garden and the fireplace if smoke is the issue, plus a line on when the problem appears, such as only in strong wind or only when the fire is lit. Leaks are prioritised on our books, and a wet roof is made safe before anything else happens.
Roof repairs we carry out come with a written workmanship guarantee of 10 years, and the site is left tidy. For a wider look at stack faults, the chimney repairs hub is the place to start.