Do I Need a Chimney Liner ?
Technically, you can install a stove or wood burner without a liner—but in practice, it’s rarely worth the risk. Whether you're dealing with an older, oversized chimney or just want the most from your appliance, fitting a liner isn't just about safety—it's key to performance, compliance, and long-term reliability.
🛡️ Safety: Keep Fumes Where They Belong
Older brick chimneys weren’t designed to handle the high-temperature fumes produced by modern wood burners. Over time:
Mortar joints degrade, and gaps or voids open up inside the flue.
This can allow carbon monoxide and other gases to leak into lofts, bedrooms, or cavity spaces.
HETAS makes it clear: if a flue isn’t proven sound and suitable, it must be lined. A stainless steel liner creates a sealed path from your stove/wood burner to the chimney terminal—keeping harmful fumes out of your home.
🌡️ Efficiency: Better Burn, Less Fuel, More Heat
This is where liners make the biggest difference.
Most existing chimneys—especially in older properties—are far too wide for a stove/wood burner. That mismatch causes:
Poor draw, making it harder to light the fire and keep it going.
Flue gas cooling, which reduces combustion efficiency.
Wasted heat, as warmth escapes up a cold, open stack instead of heating your home.
A properly fitted liner:
Matches the flue size to the stove/wood burner’s design, allowing it to run at peak efficiency.
Improves draw, making lighting quicker and more consistent.
Helps retain flue gas temperature, keeping combustion clean and steady.
Means more heat into the room, less up the chimney.
Reduces fuel use, as your wood burner reaches and maintains its optimal burn zone faster.
You’ll also see fewer problems like:
Glass blackening
Sluggish lighting
Smoke spillage into the room during cold starts or downdraught conditions.
Simply put, you’ll burn cleaner, get more warmth from your wood, and spend less on fuel.
💨 Steel Grades: 316L vs 904L
Not all liners are the same. For wood-only use, 316L stainless steel is typically fine. But if you’re planning to burn smokeless fuels or run your stove/wood burner at a low rate for long periods, 904L is more resistant to corrosion and usually carries a longer warranty.
🧱 Insulating the Liner (When Needed)
In cold or external chimney stacks, it’s often a smart move to insulate the liner:
This helps maintain a consistent flue temperature, improving draw.
It also reduces condensation and the build-up of corrosive tars like creosote.
Insulation can be added via wrap or loose-fill methods depending on access and chimney construction.
🌫️ Cuts Creosote and Condensation Risks
Cool, poorly-drawn flue gases are a recipe for creosote and water condensation:
Creosote is highly flammable and a leading cause of chimney fires.
Condensation forms acidic deposits that corrode masonry and can show as damp inside the home.
Liners minimise both by keeping the flue warm and gases moving. That means a cleaner, safer system—and less frequent sweeping or repairs.
🏠 Insurance, Legalities & Common Sense
Fitting a stove/wood burner and liner is classed as a controlled service under UK Building Regulations. It must be signed off by either a HETAS-registered installer or Building Control.
Also:
Some home insurers now require a lined flue when a stove/wood burner is in use.
If there’s a chimney fire and the flue wasn’t proven safe, you could be left without cover.
Having a HETAS certificate and sweeping history gives you both protection and peace of mind.
⚠️ When Might a Liner Not Be Needed?
If your chimney already has a sound concrete or clay liner, a stainless steel liner may not be essential—but that depends on condition.
A CCTV inspection should be carried out to confirm integrity.
Even then, many installers recommend a flexible liner for:
Improved performance
Simpler servicing and sweeping
Easier replacement of future appliances
💬 Final Word
If you’re fitting a stove/wood burner, don’t skimp on the flue. A liner ensures your appliance works efficiently, burns cleanly, and keeps your home warm and safe.
