A wood-burning fireplace or stove leaves soot and creosote inside the chimney, and that build-up can block the flue or catch fire. Most homes that burn wood regularly should have the chimney swept at least once a year, ideally before winter, and more often if you use the fire a lot. You can clean the firebox and glass yourself, but sweeping the flue is usually a job for a professional chimney sweep.
Why chimneys need cleaning
- Chimney fires. Creosote is a tar-like residue from wood smoke. It’s flammable, and a thick layer can ignite inside the flue, sometimes with enough heat to damage the chimney or set the roof alight. Thatched roofs are especially vulnerable.
- Carbon monoxide. A blocked or narrowed flue can push smoke and CO back into the room.
- Poor draw. Soot, bird nests and debris restrict airflow, so the fire smokes, struggles to light and gives less heat.
- Damage. Moisture plus soot is corrosive, and a sweep can spot cracked masonry, rusted flue pipes and failing cowls early.
How often should a chimney be swept?
| How you use it | Suggested sweeping frequency |
|---|---|
| Wood fire used most winter evenings (Highveld, Free State, Karoo) | At least once a year, before winter; consider a mid-season check if you burn heavily |
| Occasional wood fires (coastal areas, weekends only) | Once a year, or every couple of years for very light use, with an annual inspection |
| Closed combustion stove burning dry hardwood | At least once a year |
| Burning wet or soft wood, or frequently smouldering the fire | More often: these produce more creosote |
| Unused for a few years, or newly bought house | Inspect and sweep before the first fire |
| Gas fireplace (flued) | No soot sweeping as such, but have the flue and appliance checked by a registered gas installer as the manufacturer recommends |
These are general guidelines. Always follow the manufacturer’s maintenance recommendations for your fireplace or stove.
Warning signs your chimney needs attention
- Smoke coming into the room, or the fire is harder to light and keep going than it used to be
- A strong smoky or tarry smell from the fireplace, especially in hot or humid weather
- Black, flaky or shiny tar-like deposits in the firebox, on the damper or at the base of the flue
- Soot falling into the fireplace
- Glass on a closed combustion unit blackening quickly
- Signs of birds or nests at the top of the chimney
- Rust, cracks or loose bricks on the chimney, or water stains on the ceiling around the flue
Signs of a chimney fire
A loud roaring or rumbling sound, dense smoke, a strong hot smell, or flames and sparks shooting from the top of the chimney.
If you think the chimney is on fire:
- Get everyone out of the house.
- Call the fire department.
- If it’s safe, close the stove door and air controls, or the fireplace damper, to starve the fire of air.
- Don’t pour water into a hot stove or flue.
- Don’t use the fireplace again until it’s been inspected.
Keep a fire extinguisher in the home and make sure everyone knows where it is.
DIY: how to clean a fireplace
You can safely clean the parts you can reach. Always wait until the fire has been out for at least a day and the ash is completely cold.
You’ll need: a metal ash bucket with a lid, a small shovel and hand brush, a dust mask, gloves, old sheets or drop cloths, and a stiff brush.
- Protect the room. Lay drop cloths around the hearth and move rugs and furniture back.
- Remove the ash. Scoop it into a metal bucket and put it outside, away from the house. Embers can stay hot for a long time, so never put ash into a plastic bin or onto a compost heap straight away.
- Brush the firebox. Brush soot off the walls and floor of the firebox and grate.
- Check the damper (on open fireplaces) for soot build-up, and make sure it opens and closes freely.
- Clean the glass on a closed combustion unit when cool, using a cleaner made for stove glass.
- Look up the flue with a torch. If you see thick, flaky or shiny tar-like deposits, call a sweep.
Should you sweep the chimney yourself?
DIY chimney rod and brush kits exist, but sweeping is messy, often involves working on the roof, and doesn’t include the inspection a professional does. Glazed, shiny creosote may need specialised tools to remove. For most homeowners, especially with steep roofs, thatch or tall chimneys, a professional sweep is the safer choice.
What a professional chimney sweep does
| DIY cleaning | Professional chimney sweep | |
|---|---|---|
| Firebox, grate and glass | Yes | Yes |
| Full flue sweep | Possible with rod kits, but messy | Yes, with rods, brushes and vacuums |
| Glazed creosote removal | Difficult | Specialised tools |
| Inspection of flue, cowl and roof seals | Limited | Yes |
| Bird nest and blockage removal | Only if reachable | Yes |
| Roof work | Risky | Done with proper equipment |
| Cost | Your time | Entry to mid price band, depending on access and condition |
A good sweep will typically seal the fireplace opening, sweep from below or above, vacuum the soot, check the cowl and flashing, and tell you about any damage. Ask for a short written report or photos, especially if you’re buying or selling a house or need it for your insurer.
If the inspection shows a damaged chimney or the wrong flue size, you may need repairs or an upgrade. New or altered fireplaces and chimneys fall under Part V (Space heating) of the National Building Regulations, with SANS 10400-V as the deemed-to-satisfy standard, and may need municipal plan approval. Get quotes from fireplace installers and chimney specialists.
How to keep your chimney cleaner for longer
- Burn dry, seasoned hardwood. Wet wood produces far more smoke and creosote. See our braai wood guide for good local hardwoods.
- Never burn treated or painted timber, pallets with chemical treatment, plastic, cardboard boxes or rubbish.
- Avoid smouldering fires. On a closed combustion fireplace, run the fire hot for a while after lighting and don’t close the air controls right down overnight.
- Fit a cowl with a mesh to keep birds and rain out.
- Fit smoke and CO alarms near the fireplace (see smoke and CO detectors).
FAQ
How do I know if my chimney needs cleaning?
Smoke coming into the room, a fire that’s hard to light, a tarry smell, falling soot and black, flaky or shiny deposits in the flue are all signs. If you’ve had a full winter of regular fires since the last sweep, it’s due.
Do I need to sweep a chimney I hardly use?
Yes, at least periodically. Even an unused chimney can be blocked by bird nests, debris or crumbling masonry. Have it inspected before you light the first fire of the season.
Can I use a chemical chimney-cleaning log instead of a sweep?
Products like these may help loosen some deposits, but they don’t replace a physical sweep and inspection. Follow the product instructions and still have the chimney swept regularly.
Do gas fireplaces need chimney cleaning?
Gas burns much more cleanly than wood, so there’s little soot. Flued gas fireplaces still need their flue and appliance checked, by a registered gas installer, as the manufacturer recommends. See our fireplace guide for the differences between fireplace types.
More heating & fireplaces guides
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