Chimney Liner Installation for Wood-Burning and Multi-Fuel Stoves

Many homes in Northumberland and Tyne and Wear have chimneys that were built for open coal fires decades ago. They can often serve a modern stove well, but not always as they are. A chimney liner creates a smooth, sealed flue of the right size inside the existing chimney, helping the stove draw properly and keeping smoke and gases where they should be. This page explains when a liner is needed, what the work involves and what affects the cost.

Why line a chimney?

A stove produces a smaller volume of cooler flue gases than an open fire. In a large, cold, unlined chimney, those gases can cool quickly, leading to poor draw and condensation. That condensation mixes with soot to form tar, which can stain chimney breasts and build up inside the flue. A liner of the correct diameter keeps gases warmer and moving, and a sealed liner also protects against leaks through cracked mortar joints.

Common reasons for lining include:

• The chimney fails a smoke test or shows signs of leaking.
• The flue is much larger than the stove needs, so the draw would be weak.
• The chimney is old, the mortar is deteriorating or the history of use is unknown.
• The chimney is shared with another flue, or you plan to burn smokeless fuel, which can produce corrosive deposits.

A liner is not always required. If a chimney is in good condition, sound and suitably sized, a stove may be connected directly. We assess this rather than assuming either way.

What the installation involves

Chimney assessment

We look at the chimney from inside and out, including the stack, pot and the fireplace opening. A sweep before the work is often needed. A smoke test shows whether the chimney leaks and how well it draws. We measure the flue to confirm a liner will pass through any bends or offsets.

Choosing the liner

Flexible stainless steel liners are the most common choice for stove installations. They come in different grades. A standard grade is generally suitable for wood, while a higher grade is usually recommended for multi-fuel stoves and smokeless fuel. The diameter must never be smaller than the stove's flue outlet. Approved Document J sets minimum flue sizes, and many stoves need a 150mm flue, while a smaller size is permitted for some appliances, including certain Defra-exempt stoves. We confirm the right size for your stove.

Fitting

The liner is lowered from the top of the chimney, which usually means working safely at height with an access tower or scaffolding. At the top, it is secured with a clamp and top plate and finished with a suitable pot hanger or cowl. At the bottom, it connects to the stove through a register plate and an adaptor. Where appropriate, the space around the liner may be insulated, either with a wrap or with loose insulation, to help keep flue gases warm.

Testing and records

Once the stove is connected, we test the flue and check that it draws correctly. The details of the flue are recorded on a notice plate, and the installation is certified as part of the stove installation, through a competent person scheme such as HETAS or by Building Control.

Regulations

Lining a chimney as part of a stove installation falls within Part J of the Building Regulations, and the flue must meet the guidance in Approved Document J. Relining a chimney is notifiable building work in its own right. On some buildings, changes at the chimney top, such as new pots or cowls, may need permission if the property is listed or in a conservation area. If you are unsure, check with your local planning authority. Our guide to stove regulations in England explains the background.

What affects the cost

Liner installations vary a lot from house to house. The main factors are:

• The height of the chimney, which sets the length of liner needed.
• The liner grade and diameter.
• Access to the stack, and whether scaffolding is needed.
• Repairs to the stack, pot or flaunching before lining.
• Insulation around the liner and the type of cowl or terminal.
• Work at the fireplace end, such as a new register plate or opening up.

For typical, approximate figures, see our guide to what stove installation costs. Every home is different, so we always provide a written quote after an assessment.

No chimney?

If your home has no chimney, or the chimney cannot be used, a twin-wall insulated flue is usually the alternative. Our article on installing a wood burner without a chimney explains how that works.

Looking after a lined chimney

A liner still needs sweeping, at least once a year for wood and more often with heavy use. Burning dry fuel reduces deposits and helps the liner last. Our article on how often a chimney should be swept has more detail. If you are planning a new wood burner, we can assess the chimney and quote for the liner as part of the same job.