Cart
0
0.00 €
What Is Twinwall Stove Pipe?
Twinwall stove pipe is a type of flue system designed to safely carry hot fumes from your wood-burning or multi-fuel stove to the outside of your property. Unlike the simple black pipe you see coming directly out of the stove, twinwall is a factory-made, insulated chimney system. It is typically used when you do not have a traditional brick chimney, or when you need to route the flue through rooms, roofs, or outside walls in a safe and compliant way.
The key difference between twinwall and single wall flue is the construction. Single wall flue is just one layer of metal, so it gets very hot on the outside and must be kept well away from any combustible materials such as timber, plasterboard, or furniture. Twinwall stove pipe, by contrast, is made from two layers of stainless steel with a layer of high-quality insulation between them. This insulated double wall design keeps the outer surface much cooler and helps maintain flue gas temperature inside the pipe.
Because the inner wall stays hotter, the flue draws better, which supports cleaner, more efficient burning and helps reduce the build-up of soot and tar. At the same time, the cooler outer wall allows for reduced clearances to combustibles, making it easier to route the chimney through tight spaces while still meeting safety regulations. For homeowners, the main benefits of twinwall stove pipe are improved safety, better stove performance, and more flexible installation options. It is a trusted solution for new installations, renovations, and for safely connecting modern wood-burning and multi-fuel stoves where no existing chimney is available.
Twinwall Stove Pipe Buying Guide
How do I choose the correct twinwall stove pipe diameter?
Start with your stove manufacturer’s instructions. Most modern wood stoves use 5" (125 mm) or 6" (150 mm) flue outlets. Your twinwall system should normally match the stove’s flue collar size unless the manual explicitly allows a change. Never reduce the diameter below the stove outlet, as this can cause poor draw, smoke spillage, and invalidate warranties or approvals. If you are unsure, match the outlet size and keep the same diameter all the way to the terminal.
Which stoves are compatible with twinwall systems?
Twinwall insulated flue systems are designed for stoves that do not have an existing chimney or where the existing chimney is unsuitable. They are compatible with most wood‑burning and multi‑fuel stoves, and many gas or pellet appliances, provided the flue system is rated for the fuel type and temperature class. Always check the stove manual for flue temperature, pressure, and material requirements, and confirm that the twinwall brand you choose is certified for that application.
What clearances do I need from combustibles?
Clearances vary by manufacturer and certification, but typical twinwall systems require 50–70 mm minimum air gap from any combustible material, including timber studs, plasterboard, and insulation. Use only tested fire‑stop plates and support components where the flue passes through floors, walls, or roofs. Do not pack insulation directly against the outer casing unless the system is specifically approved for that use. Always follow the exact clearance figures in the installation manual and local building regulations.
Should I run the twinwall flue inside or outside the building?
An internal run is usually preferred because the flue stays warmer, improving draw and reducing condensation and creosote. It often gives better stove performance and less risk of tar staining. External runs are sometimes necessary or simpler to install, but they can cool more quickly and may require extra attention to height, bracing, and weatherproofing. When choosing, consider aesthetics, structural fixing points, roof layout, and access for sweeping and maintenance.
How do I handle roof and wall penetrations safely?
Use only manufacturer‑approved components for all penetrations. For roofs, this usually means a dedicated flashing matched to the roof pitch and material, plus a storm collar and appropriate fire‑stop or support plate below. For walls, use an insulated wall sleeve or wall penetration kit that maintains the required clearance to combustibles. Seal externally with high‑temperature, weather‑resistant products and ensure the flue is properly supported on both sides of the penetration to avoid stress on joints.
How many bends can I use in a twinwall system?
Most standards and manufacturers limit you to a small number of bends, typically no more than four 45° bends in total (or two 90° equivalents). Excessive changes of direction reduce draft and increase soot build‑up. Use the gentlest angles possible, keep horizontal runs very short and slightly rising, and support the flue near every change of direction. If your layout needs more than the recommended number of bends, reconsider the stove position or route.
What supports and brackets are required?
Twinwall systems must be structurally self‑supporting and not rely on the stove to carry their weight. Use base supports, wall brackets, and roof braces as specified by the manufacturer, usually every 1.5–2.5 m vertically and at each offset or change of direction. External stacks above the roof often need additional guying or bracing, especially in exposed or windy locations. Correct support prevents joint separation, leaks, and long‑term damage to both the flue and the building.
Which safety standards and certifications should I look for?
Look for twinwall systems tested and certified to recognised standards such as EN 1856‑1 in Europe (e.g., designation T600, suitable for high‑temperature solid fuel) or equivalent national codes. The product label should show temperature class, pressure class, corrosion resistance, and distance to combustibles. In many regions, installation must also comply with building regulations (for example, minimum flue height above the roof ridge and neighbour boundaries) and may need sign‑off by a qualified installer or inspector.
What are common mistakes to avoid when buying a twinwall system?
Frequent mistakes include choosing the wrong diameter, mixing components from different brands, ignoring minimum clearances, and underestimating the total height needed for good draft. Others include using too many bends, failing to support the flue adequately, and skipping certified components for roof or wall penetrations. Avoid using single‑wall pipe where insulated twinwall is required, and never improvise with non‑approved parts. Planning the full route and component list before purchase helps prevent costly changes later.
Do I need a professional installer for twinwall stove pipe?
While some competent DIYers can install twinwall systems, many jurisdictions require installation or final inspection by a certified professional. A qualified installer will design the route, size the system correctly, and ensure compliance with local codes and manufacturer instructions. Professional installation also reduces the risk of leaks, poor performance, and fire hazards, and may be required to maintain product warranties and home insurance coverage. When in doubt, consult a specialist before starting any work.