Such a chimney suits a stove, fireplace or solid fuel boiler, withstands a soot fire and lasts a long time, but it is heavy and needs its own base. We name the price based on the height of the house, the system diameter and access.
What a modular chimney is
In a modular system every element is made in a factory and fits the next one. At the bottom there is a base element with a condensate collector and drain opening, above it a cleaning door element, a connection element for the appliance and then straight pipes up to the roof. Around the ceramic pipe there is insulation or a ventilated air gap, and the whole thing is enclosed by casing blocks. The casing blocks often also have a second duct for ventilation.
That is why a modular chimney is also called a block chimney or a ceramic system chimney. Compared with a brick-built chimney it has a smooth inside, warms up faster and draws better, and the ceramic withstands the acidic condensate that forms when flue gases cool down.
When a modular chimney is the right choice
- A new house or a major rebuild, where the chimney can be installed before interior finishing.
- There is room for a base: in the basement or on the foundations, not on timber floor joists.
- You plan to connect a wood stove, fireplace or solid fuel boiler that needs a flue able to withstand a soot fire.
- You want a ventilation duct in the same block.
If the house is already finished and there is no room for a base, a lighter solution is stainless steel chimney installation. If an old masonry chimney is sound, chimney lining is enough.
How modular chimney installation is done
- Design and measurements We choose the diameter according to the appliance manufacturer's requirements and set the chimney's position so it runs straight through the floors and comes out in the right place in relation to the ridge.
- Base The chimney stands on a non-combustible, load-bearing base that carries the weight of the whole chimney. It is not placed on timber joists.
- Bottom elements We install the base element with condensate drainage, the cleaning door element and the connection element at the height where the appliance will be connected.
- Pipes and blocks We join the ceramic pipes with acid-resistant mortar, put insulation around them, then the casing blocks. We set reinforcement in the corners and fill them with mortar.
- Floors The chimney passes through a floor with a gap filled with non-combustible insulation. Floor joists are not supported on the chimney.
- Above the roof The part above the roof is finished with facade panels or render, a crown slab and a cap. The height depends on the distance to the ridge.
- Check Once the mortar has set, we connect the appliance and check the draught.
LBN 231-15 (Cabinet Regulation No. 310 of 16.06.2015), point 53: flues are fitted with cleaning doors whose area is not smaller than the flue channel's cross-section. Point 54: combustible materials at least 100 mm from the outer surface of a masonry chimney and 200 mm from cleaning doors. Points 61–62: the top at least 0.5 m above the roof covering; if closer than 1.5 m to the ridge, 0.5 m above the ridge. At 1.5–3 m from the ridge, no lower than the ridge; further than 3 m, no lower than a line at 10° from the ridge. Point 63: height from the grate to the outlet at least 5 m. Source: likumi.lv, checked 04.11.2026.
The most common mistakes
- The chimney is supported on a timber floor or joists: over time it settles and cracks.
- Floor joists are built into the chimney block without a gap: the timber is exposed to prolonged heat.
- There is no condensate drain: moisture soaks into the blocks, and patches appear on the finish.
- The cleaning door is built in behind wall finishes: the chimney sweep cannot reach it.
- The chimney is too low in relation to the ridge: the wind pushes smoke back down.
The fire safety regulations also set a distance from the inner surface of the flue to combustible structures, but this requirement does not apply if the manufacturer specifies otherwise. So we install the system exactly according to the manufacturer's instructions, and the instructions should be kept with the house documents.
Cabinet Regulation No. 238 “Fire Safety Regulations” of 19.04.2016, points 64–66: from the inner surface of the flue to a combustible structure 380 mm (appliance fired for up to 3 hours) or 510 mm (longer), 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 much does modular chimney installation cost?
There is no single price. It depends on the system diameter and whether it has a ventilation duct, the chimney height from the base to the top, the number of floors it passes through, preparing the base, access to the roof and the finish of the top section. Materials are priced separately, and they are the largest part of the price. In the form, give the number of storeys and the appliance data, and the specialist will name the price before the work.
Sources
- Cleaning doors (LBN 231-15, point 53), distances (point 54), height above the roof and ridge (points 61–62), total height 5 m (point 63), separate flue channel (point 41) checked 4 November 2026
- Distances 380/510 mm unless the manufacturer specifies otherwise (Cabinet Regulation No. 238, points 64–66) checked 4 November 2026