Creosote is the black, tar-like residue that condenses inside your flue as wood smoke cools. Once it builds up past 3mm, it becomes flammable — and a flue fire hits temperatures that will melt a stainless steel liner. Regular cleaning is the cheapest insurance policy your fireplace will ever have.
The rule of thumb
- Light seasonal use (10–15 evenings a winter): sweep once a year, in autumn.
- Regular use (3–5 evenings a week through winter): sweep twice — once at the start of winter, once mid-season.
- Daily use / primary heat source: sweep every 3 months during use.
- Rule: every 1 tonne of wood burned = one sweep due.
Signs you're overdue
The fire is harder to light and doesn't draw properly. There's a strong smoky smell in the room when the door opens. You can see dark staining above the fireplace opening. Any of these means creosote is restricting airflow — book a sweep before your next fire.
What a professional sweep costs
A full flue sweep and inspection runs R750–R1,500 in the Western Cape depending on flue height and access. It takes about an hour, uses no chemicals, and includes checking the door seal, baffle plate and firebox for wear.
DIY vs professional
You can buy a flue brush set for R400 and do a basic sweep from the roof yourself if the flue is straight and accessible. What you can't easily do is inspect the seals, spot warped baffle plates, or identify creosote that has hardened into glaze — which needs mechanical removal. For a once-a-year job, professional is worth it.
Why Cape homes build up creosote faster
Coastal humidity along the Atlantic seaboard and the West Coast — Milnerton, Table View, Melkbosstrand and Langebaan — cools flue gases faster, so more tar condenses on the inside of the pipe. Winelands homes in Paarl, Stellenbosch and Franschhoek face a different problem: long, cold nights where the fire is shut down low for hours. A smouldering fire is the worst creosote producer there is.
In both cases the fix is the same: burn dry hardwood such as rooikrans or kameeldoring below 20% moisture, run the fire hot for the first 20 minutes, and avoid closing the air control completely overnight.
When cleaning isn't enough: replacing the flue
A flue that has had a chimney fire, shows rust-through or has sections that no longer seal properly should be replaced rather than swept. Our single-storey stainless steel through-the-roof kits are priced by diameter, all incl. VAT:
- Ø130 mm kit (fireplaces up to 10 kW): R 6 715.
- Ø150 mm kit (11–15 kW): R 7 390.
- Ø180 mm kit (16–18 kW): R 8 505.
- Ø200 mm kit (larger units): R 9 790.
- Double-storey homes: add R 3 000 for the extra flue length.
- Ceiling plates to neaten the ceiling penetration: R 218 – R 309.
Not sure which flue size you have?
Measure the outside of the pipe just above the fireplace collar, or check the kW rating on the appliance plate. You can also describe your home to the flue advisor on our Flues page — it recommends the right kit, whether you need the double-storey add-on, and what the installer will need on the day.
Our team services and replaces flues across Cape Town, the West Coast and the Cape Winelands. Transport is R 500 for the first 20 km and R 10 per km after that.
Quick answers
Can a chimney fire happen in a new flue? Yes. A new flue can build up dangerous creosote in a single season if wet wood is burned or the fire is kept smouldering.
Do gas fireplaces need their flues cleaned? Less often — an annual check is usually enough, together with the gas service and leak test.
Should I sweep before or after winter? Before is essential; after is ideal for heavy users, because creosote left over summer absorbs moisture and corrodes the flue.
Written by
Progress Group
Fireplace, braai and gas specialists since 1990 — showroom in Bellville, installations across Cape Town and the Western Cape.