Tar is combustible, clings tightly to the walls and narrows the channel, so it is more dangerous than ordinary soot. We remove it mechanically, and a thick layer is softened first. We name the price once we see how thick the layer is. Write in the form what you burn and what the deposits look like.
How to tell tar from soot
| Stage | What it looks like | How it is removed |
|---|---|---|
| Soot | black, fluffy, falls off when touched | with an ordinary brush, during normal cleaning |
| Granular tar | crunchy black flakes and lumps | with a harder brush or a rotary tool |
| Glazed tar | shiny, hard, like set black glaze; sometimes runs out of the door | softened first, then removed mechanically, often in several rounds |
Tar is sometimes called creosote. Signs that there is tar in the flue: brown or black sticky stains on the chimney in the attic, a sharp, sour smell by the stove even when it is not lit, and bits of soot that stay on the walls after ordinary cleaning.
Why tar forms in the flue
- Damp firewood: the water vapour cools the smoke, and resinous substances settle on the walls.
- Smouldering at low output: a long-burn boiler or stove with the air supply closed burns slowly, and the smoke in the chimney is cool.
- A flue that is too wide or not insulated: the smoke cools before it reaches the top, especially in a chimney on an outside wall.
- Conifer offcuts, bark, painted wood and household waste.
- A boiler without a buffer tank that runs in reduced mode most of the time.
If the tar is only removed but the cause stays, it comes back after one season. So you need to find out what causes it in your case and what can be changed: the firewood, the way you heat or the flue. A masonry flue that is too wide is often helped by chimney lining.
How tar removal works
- Assessment We look at the flue through the door and from the top or with a camera, and work out how thick the layer is and where it is. The thickest tar is often in the upper part and the chimney head.
- Ordinary cleaning First we sweep out everything a brush can remove, so that only the hard layer is left.
- Mechanical removal We remove granular tar with a harder brush or a rotary tool on flexible rods. We choose the tool by the flue material so as not to damage the brickwork or the liner.
- Softening For glazed tar we use a tar-softening product that is put into the firebox over several fires. The tar becomes brittle and can be removed at the next cleaning.
- Repeat cleaning and check After softening, the flue is cleaned again, the remains are removed and the walls are checked. The result is recorded in the certificate.
Tar must not be burnt out. It is forbidden, and burning tar heats the flue so much that it cracks. If tar has already burnt in the chimney, a check is needed first: chimney check after a soot fire.
Cabinet Regulation No. 238 “Fire Safety Regulations”, sub-point 89.11: it is forbidden to clean flues, natural ventilation ducts and mechanical ventilation systems by burning them out. Source: likumi.lv, checked 04.11.2026. Regulations checked 04.11.2026; from 2 January 2027 they will be replaced by new fire safety regulations, which we will check as soon as they are adopted.
When a camera inspection is needed after tar
Thick tar hides the condition of the wall. Once it is removed, it may turn out that there are cracks and crumbled joints underneath, and corrosion in a liner. If the tar was thick or has already burnt in the chimney, we recommend examining the flue with a camera: camera inspection. A damaged flue must not be used, so we record the findings in the certificate and offer the repair separately.
How much chimney tar removal costs
There is no single price for tar removal, because a thin granular layer and glazed tar along the whole flue are completely different jobs. The price depends on:
- the type and thickness of the tar, and how much of the flue it covers;
- whether mechanical removal is enough or softening and a repeat cleaning are needed;
- the length, diameter and material of the flue: brickwork, ceramic or a stainless steel liner;
- the height of the chimney and access to the roof;
- whether a camera inspection is needed along with the cleaning.
Ordinary flue cleaning, where the soot is removed with a brush, costs from €100. If during tar removal we see that more work is needed, we tell you and agree the price before we continue. Other prices: prices.
Sources
- It is forbidden to clean a flue by burning it out (89.11); it is forbidden to use a damaged flue (89.1) checked 4 November 2026
- Soot builds up from wet firewood and household waste (VUGD, 31.10.2025) checked 4 November 2026