Flue lining is the installation of a new flue gas passage inside an existing chimney shaft. It is one of the most common investments in a chimney and simultaneously the one about which property owners know the least.
This guide explains when you need flue lining, what options are available and how much it will cost.
When is chimney lining necessary?
- Old, cracked chimney masonry - Historic brick or stone chimneys crack over time. Flue gases and condensate escape through these cracks, which is dangerous and damages the masonry.
- Fuel change - Particularly when switching from solid fuels to gas or vice versa. A chimney designed for one fuel type may not be suitable for another.
- Replacing a boiler with a more powerful one - Different output = different temperature and flow conditions in the flue.
- Condensate issues - With gas boilers, condensate seeps through old masonry and causes moisture damage to the building.
- Reconstruction and final approval - The building authority may require flue lining as a condition for obtaining the completion certificate.
A simple rule: If your chimney sweep states during an inspection that the chimney is non-compliant, lining is generally cheaper than demolition and constructing a new chimney.
Insert types, stainless steel vs. Ceramic
🔩 Stainless steel liner (flexible spiral)
✓ Lower acquisition costs
✓ Installation without demolition
✓ Suitable for gaseous and solid fuels
✓ Flexible: passes through curved ducts
✗ Shorter lifespan than ceramic
✗ More difficult cleaning
✗ Not always suitable for high temperatures
Best for: gas boilers, less demanding installations, older houses with curved flues
🧱 Ceramic insert
✓ High resistance (over 1 000 °C)
✓ Lifespan of 30+ years
✓ Excellent for solid fuels
✓ Easier cleaning
✗ Higher price
✗ More complex installation
✗ Requires a straight duct passage
Best for: wood-burning stoves and fireplaces, pellets, coal, new installations, renovations.
How does the installation proceed?
- Inspection and selection of the insert - The chimney sweep will measure the flue, determine its length and curvature, and based on this recommend the type and size of the liner.
- Preparation of the duct passage - The flue will be cleaned (milling if necessary). A slight widening may be required for a ceramic liner.
- Insert installation - The stainless steel spiral is inserted from the top through the flue downwards. Ceramic components are assembled from the bottom upwards with overlaps and sealed with heat-resistant sealant.
- Appliance connection - The insert is connected to the boiler or stove in the utility room or a room with a heater.
- Inspection and protocol - After installing a flue liner, an inspection of the flue is mandatory. The chimney sweep will issue an inspection report.
Do you need to assess whether your chimney requires a liner? I will attend and carry out a free assessment when you book the inspection.
Call 277 278 918Cost of chimney lining in Praha 2026
Indicative price list: Praha 2026
The total cost of lining a typical residential chimney (7–10 m) in Praha ranges between 25 000 and 70 000 Kč including materials and mandatory inspection. I will provide the exact price after an on-site visit.
Is lining a chimney an investment or a necessary evil?
It depends on your perspective. Lining extends the chimney's lifespan by decades, reduces fuel consumption (thanks to better thermal insulation of the flue gas path) and eliminates the risk of flue gas leakage. Compared to building a new chimney, it is significantly cheaper. Compared to buying a property with an unlined and non-compliant chimney, it is a necessary condition for safe operation.