We install the system with a cleaning door, passages and a cap and check the draught. We name the price once we know the appliance, the chimney length and its route through the house.
How an insulated steel chimney is built
An insulated, or twin-wall, chimney has an inner stainless steel pipe, mineral wool insulation around it and an outer steel casing. The insulation keeps the flue gases warm right up to the outlet, so the chimney draws well and less condensate and tar form in it. The outer surface stays cool enough for the chimney to pass through a floor with a passage element.
A single-wall steel pipe is only suitable as the connection from the appliance to the chimney, or as a liner in an existing masonry chimney. As a stand-alone chimney through an attic or outdoors it cools down, and tar builds up in it.
How to choose the right system
- Diameter: whatever the appliance manufacturer requires. For solid fuel the building code requires at least 150 mm, for gas at least 80 mm.
- Steel: acid-resistant steel also suits boilers with a low flue gas temperature. A thicker inner pipe lasts longer if you burn wood.
- Marking: the system's label states the temperature class, soot fire resistance and the distance to combustible materials in millimetres.
- Components: a connection with a cleaning door, a condensate collector, passages through every floor and the roof, fixings, a cap.
The marking matters because the fire safety regulations' distances to timber do not apply if the flue manufacturer specifies otherwise. The manufacturer's stated distance is what we keep to during installation. If the system has no such document, we keep to the distances in the regulations.
LBN 231-15 (Cabinet Regulation No. 310 of 16.06.2015), point 40: minimum cross-section 175 cm² or 150 mm for solid fuel and 50 cm² or 80 mm for gas and liquid fuel. Point 55: metal flues are designed and installed to the applicable standards (point 84 names standard LVS EN 1856, part 1). Cabinet Regulation No. 238 “Fire Safety Regulations” of 19.04.2016, points 64–66: 380 or 510 mm from the inner surface of the flue to a combustible structure, unless the manufacturer specifies otherwise. 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.
How installation is done
- Route and measurements We decide where the chimney will cross the floors and the roof, and measure the length from the appliance to the required height above the roof.
- Support The chimney is supported on a floor support or a wall bracket. The full weight must not rest on the appliance unless the manufacturer allows it.
- Connection and door At the bottom we install a T-piece with a cleaning door and a condensate collector. The appliance is connected with a connector pipe.
- Sections and passages We assemble the sections so the inner pipe is oriented with the smoke flow, and secure them with clamps. In each floor we fit a passage element and non-combustible insulation.
- Fixings We fix the chimney to the wall or floors with the manufacturer's brackets at the spacings the instructions give.
- Above the roof and cap If needed, we brace the chimney above the roof with guy wires, then fit the cap. The height depends on the distance to the ridge.
- Check We check the draught and tightness.
LBN 231-15, point 53: cleaning doors with an area not smaller than the flue channel's cross-section. Point 54: combustible materials at least 100 mm from the outer surface of a metal chimney, 300 mm from flues and 200 mm from cleaning doors (for appliances up to 120 kW). Point 62: the top at least 0.5 m above the roof covering. Source: likumi.lv, checked 04.11.2026.
Inside or outside on the facade
A chimney inside the house stays warmer, so it draws better, and on its way up it heats the rooms. It needs passages through every floor and the roof. A chimney on the facade takes no space from the rooms and can be installed without work inside, but it needs a passage through the wall and more fixings, and it is longer, because it has to go all the way up to roof height. More detail: flue through a wall.
How much does stainless steel chimney installation cost?
There is no single price. It depends on the diameter, the insulation thickness and steel type, the chimney length, the number of floor and roof passages, facade fixings and access to the roof. Materials are priced separately. The specialist names the price after you submit the form, before we start work. Other prices: prices.
Sources
- Minimum cross-section (LBN 231-15, point 40); metal flues to standards (points 55, 84); cleaning doors (point 53); distances (point 54); 0.5 m above the roof (point 62); stoves not connected to gas flue channels (point 24) checked 4 November 2026
- Distances 380/510 mm unless the manufacturer specifies otherwise (Cabinet Regulation No. 238, points 64–66) checked 4 November 2026