It is most needed for chimneys that run through a cold attic, along an outside wall or high above the roof, and for lined flues with a modern boiler connected. We insulate only with non-combustible materials: an insulated liner, an insulation jacket between the liner and the masonry, or an insulated metal chimney. In the form, tell us where the chimney runs and what is connected to it.
When a chimney needs insulating
- The chimney runs through an unheated attic or along an outside wall, and damp or brown patches show on it there.
- Condensation appeared after the boiler was replaced: condensation in the chimney.
- When you light the stove or boiler, smoke comes into the room for the first few minutes until the chimney warms up.
- Tar builds up quickly in the flue even though you burn dry firewood.
- A single-wall metal flue is installed outside, and in winter it is cold and ices up.
- A single-wall liner was fitted in a cold chimney, and condensate collects in it.
Insulation is not needed if the chimney runs through the warm rooms of the house and a masonry stove with hot flue gases is connected to it. And if the problem is cracks or a chimney that is too low, insulation alone will not fix it. If there is no draught at all, we look for other causes first: chimney has no draught.
Ways of insulating a chimney
| Type | Suitable for | What to know |
|---|---|---|
| Insulated liner (two steel walls with insulation between them) | an old brick chimney in a cold attic, solid fuel | the flue channel must be wide enough, because an insulated liner is thicker |
| Single-wall liner with a non-combustible insulation jacket | a flue channel in which the insulated liner does not fit | the insulation must be non-combustible and rated for flue temperatures |
| Insulated stainless steel chimney | outside against a wall, or a new flue through the roof | this is installation, not insulation: stainless steel chimney installation |
| Replacing a single-wall metal flue with an insulated one | a sauna or garage flue outside | a single-wall pipe is not wrapped in wool but replaced with a factory-insulated system |
Render on a brick chimney head protects it from rain and frost, but it is not insulation. If the head is cracked, chimney rendering or rebuilding helps.
Fire safety: non-combustible materials and distances
For insulation we use only non-combustible insulation rated for flue temperatures. Polystyrene, foam, ordinary building membranes and timber cladding close to the flue are not suitable. Insulating must not reduce the distance to timber beams, rafters and other combustible structures. In the attic this is the most common mistake: wool is packed tight against the beams, and the chimney passes its heat on to the timber.
Points 64 and 65 of the fire safety regulations set the distance from the inner surface of the flue to combustible and low-combustibility structures. The State Fire and Rescue Service (VUGD) has explained that these distances also apply to existing buildings. For a certified system the manufacturer may set different distances.
Cabinet Regulation No. 238 “Fire Safety Regulations” of 19.04.2016, point 64: at least 380 mm from the inner surface of the flue to a combustible structure if the appliance runs for up to three hours, 510 mm if longer. Point 66: points 64 and 65 do not apply if the manufacturer specifies otherwise. VUGD e-consultation (LV portāls, 27.01.2025): no exceptions are set for existing buildings. LBN 231-15, sub-points 54.1 and 54.2: combustible materials at least 100 mm from the outer surface of masonry and metal chimneys and 300 mm from flues; point 51: a flue's outer surface must not exceed 80 °C. Regulations checked 04.11.2026; from 2 January 2027 new fire safety regulations will replace them, which we will check once adopted. Sources: likumi.lv, lvportals.lv, checked 04.11.2026.
How we insulate a chimney
- Inspection We clean the flue, inspect it with a camera and measure the flue channel. In the attic we check the distances to beams and rafters.
- Choosing the solution Based on the appliance, the fuel and the flue channel size, we choose an insulated liner or a single-wall liner with an insulation jacket.
- Installation We lower the liner with insulation from the roof, install a cleaning door and a condensate collector at the bottom and fix the liner on the crown slab at the top. About the whole job: chimney liner installation.
- Check After the first firing we check the draught and the temperature of the chimney walls in the attic. If the appliance has been replaced, we draw up a certificate.
How much does chimney insulation cost?
The price depends on the length and diameter of the flue, the type of insulation (insulated liner or jacket), the height of the chimney and access to the roof, the fuel and type of appliance. It also depends on whether on the same visit we clean the flue, inspect it with a camera and fit a cap. Materials are priced separately from the labour. In the form, tell us where the chimney runs and which appliance is connected to it, and the specialist will name the price before the work. All prices: prices.
Sources
- Distance from the inner surface of the flue to a combustible structure 380 mm (up to 3 h) / 510 mm (longer) (Cabinet Regulation No. 238, 64); manufacturer's exception (66); Cabinet Regulation No. 238 loses force on 02.01.2027 checked 4 November 2026
- VUGD: no exceptions are set for not applying points 64 and 65 to existing buildings checked 4 November 2026
- Combustible materials 100 mm from masonry and metal chimneys, 300 mm from flues (LBN 231-15, 54.1–54.2); outer surface up to 80 °C (51) checked 4 November 2026