It is common to have to install a casing as part of the renovation of a chimney, if it malfunctions or if you want to install a more modern heating method. But what exactly is the installation of a chimney casing, what is it for and how much does it cost? Here are some explanations to help you warm up safely.
1 – What is a chimney casing?
To pipe a chimney, a stainless steel sheath is installed inside the conduit (usually masonry). In the form of pipes interlocked with each other, this tubing is designed to allow the evacuation of fumes in complete safety.
There are several very good reasons to install a chimney liner:
- The duct is ancien and damaged. It has become less effective against high temperatures, therefore less waterproof. The operation of the chimney becomes dangerous. The casing of the chimney is essential to avoid, for example, the migration of carbon monoxide into the house…
- Your chimney flue is too large. A casing reduces it to the right diameter.
- The chimney draws badly. A problem of draw which can be caused by a pipe that is too big or damaged, we go to the tubing!
- You want to install a heating mode more modern, such as a stove, insert or boiler. Your duct is not suitable and must be sheathed.
The interest of casing is its perfect sealing. Stainless steel does not corrode in contact with sulfuric acid (produced by sulfur and water vapour), unlike the bricks of conventional conduits. In addition, the casing can withstand very high temperatures produced by a closed hearth.
2 – Casing is strictly regulated
For any dwelling built since 2012, the chimney casing is now obligatory. But this obligation also concerns older buildings, in the case of the installation of closed hearth heating systems: inserts, stoves, boilers, etc.
This obligation comes within the framework of the standards NF DTU 24.1, which specifies the installation methods and authorized materials. The rules imposed aim to secure the facilities and their users:
- Duty to sweeping of the conduit before the installation of the casing, then once a year;
- Prohibition to tube only one part of the duct;
- Need for valves the masonry conduit;
- Obligation to carry out a test sealing after installation of the casing, test to be repeated every three years.
3 – How does a casing work?
Very simply, it is the stainless steel sheath that evacuates the combustion fumes instead of the duct. It has several advantages that make it more efficient than a conventional flue:
- He is perfectly waterproof et anti corrosion.
- The suies tarred (la bistre) do not accumulate.
- Its diameter being studied to correspond exactly to the hearth, the draw works much better. which optimizes the yield and heating performance!
- Another advantage: it avoids the condensation.
- Its main function is to to secure your facility.
- And it’s easy maintenance.
The only catch is its installation cost, although this largely depends on the initial condition of the chimney.
4 – Flexible or rigid, which type of tubing to choose?
There are different types of tubing, designed to fit your duct configuration:
- The casings stainless steel rigid install themselves in straight ducts.
- The casings stainless steel flexible adapt to angled or angled ducts. They are cheaper.
- The casings in enamelled steel are reserved for wood heating.
Some casings are single wallothers to double sidedsometimes in stainless steel concentric. The difference lies in their ability to withstand high temperatures. While in a single-walled casing the heat can rise to 150° C, a double-walled pipe maintains the temperature at 30° C. These double-skinned sheaths are safer against the risk of fire. In the event of a fire, the temperature can indeed rise to 1000° C, whereas it is 600° C in normal use. In some cases, for example if the casing must cross a floor, the double-walled pipe becomes mandatory.
5 – How to install a chimney casing?
As we have seen, the installation of a casing must comply with the NF DTU 24.1 standard. It is therefore advisable to involve a certified specialist.
- He checks the condition of the chimney and the width of the flue. If necessary, he repairs and reinforces it.
- He removes any pipes lying around.
- It ensures the sweeping and the débistrage of the conduit.
- It waits until the conduit no longer shows any humidity.
- He installs the casing in compliance with the standards
- He installs a high finishing plate on the roof and a chimney cap for waterproofing.
- It connects the casing with the heating mode (insert, stove or other).
6 – What budget should I plan for a casing?
Your investment is broken down into three main expenses:
- For an installation in perfect conformity, plan the intervention of a professional. This must be certified RGE (Recognized Guarantor of the Environment). If your chimney is dilapidated, also plan its restoration, which adds to the cost of intervention.
- The cost of materials may vary, depending on the type of materials chosen.
- The cost of casing is more or less high depending on whether it is a rigid (150 € per meter) or a flexible (70 € per meter).
In total, the expense is between €300 and €1500 depending on the configuration.
This is an expense that may seem significant. But if we put it in relation to the safety of people and property, it is worth it. We are never safe from a fire… Each year, in France, firefighters intervene on 200 fires caused by defective or clogged ducts…