Home / How to Install a Wood Stove Without a Chimney | Glowing Embers

How to Install a Wood Stove Without a Chimney | Glowing Embers

Installing a wood stove without a traditional chimney requires careful planning and adherence to safety guidelines. This guide provides a step-by-step approach to setting up a twin wall flue system, which is a common alternative for homes without existing chimneys. By following these steps, you can ensure a safe and efficient installation that meets all necessary building regulations.

Non-chimney installs

Quick Step Guide to Non-Chimney Installations

Start your system with a length of Single Wall, Vitreous Enamel Stove Pipe in the same diameter as the outlet on the stove.
Connect a Single to Twin Wall Adapter to convert from this Single Wall Pipe to insulated Twin Wall Pipe a minimum of 150mm before reaching any surface (ceiling or wall).
The remainder of the flue system must be in insulated Twin Wall Flue Pipes only from this point onwards, utilizing connectable stainless steel pipes to ensure proper fume expulsion.
For internal systems passing up through the property, you shall require Joist Supports and Ventilated Fire Stop Plates for every ceiling the system passes through.
For external systems rising up the outside of the property, this must pass through the wall at no greater than 45° with a Wall Sleeve lining the passage through the wall itself. Another 45° Elbow or Tee Piece can be connected once through the wall to turn the system vertically. This will result in a visible steel pipe along the side of the building.
Joist Supports are sufficient for supporting an internal system with Adjustable Wall Brackets providing the support for an external system every 2m maximum.
For internal systems, a Roof Support, Silicone Flashing and Storm Collar are necessary for safely passing through any roof type.
Once through the roof Surface (internal) or past the roof/gutter line (external), Twin Wall systems must attain a minimum vertical height of 1m to create a minimum horizontal clearance of 2.3m.
Finish off any system with a choice of Rain Caps or Anti-Wind Cowls.

Consulting a professional is highly recommended to ensure the safe installation of your wood burner, especially when using a twin wall chimney flue system.

What Is a Non-Chimney Installation?

Planning a brand new flue system may seem daunting at first but with this guide we hope to remove the mystery of creating a twin wall installation to suit your home, avoid the common pitfalls and understand Approved Document J of the building regulations in language we can all understand (highlighted in bold).

If you do not have an existing chimney in your home to install a wood burning stove into, a new class 1 chimney system needs to be created using Twin Wall (or Double Skin) insulated flue pipes. This Twin Wall flue system will either run internally (up through the floors of the property and exiting through the roof surface) or externally (passes out through an external wall and rising up the outside of the building, clearing the gutter line), depending on your preference and the room in which you wish to locate your new stove. It is also crucial to consider twin flue chimney regulations to ensure proper fitment and compliance with the necessary guidelines.

Why Do I Need To Use Twin Wall Flue Pipes?

The three main benefits of starting a flue system with single wall pipes are they tie in with the traditional aesthetic of a log burner, can withstand the temperatures produced in the outlet collar due to the enamel and they transfer a lot of heat to the outside of the pipe, maximising the heat output produced by the stove. However, it is for this very reason that it is unsafe and even illegal to pass a single wall pipe through a wall, ceiling or roof as the outer surface will become far too hot and may transfer that heat into nearby combustible materials such as joists and furnishings.

This is where Twin Wall flue steps in. As the name suggests, these pipes feature separate inner and outer skins with a layer of insulation between to prevent heat transfer to the outer edge of the pipe, making them safe to run through any surface type and compliant with Approved Document J of the current Building Regulations. By keeping the gases within the flue warm, this encourages the draw to continue rising and prevents cooler air outside from negatively affecting this

How to Start Your Insulated Flue System

Regardless of the flue system you plan to create, it should always commence with a piece of Vitreous Enamelled, Single-Wall Stove Pipe. This pipe should match the internal diameter of your stove's outlet collar, typically 5” or 6”, but sometimes 7” or 8”. It should be inserted into the collar using the male spigot at the bottom of the pipe. Ensure the male, narrow spigot is positioned at the bottom, as reversing it will prevent proper connection to the Single to Twin Wall Adapter. The outlet collar diameter sets the minimum diameter for the entire flue system and should never be reduced. To seal this connection, use at least 1200°C heat resistant cement or silicone sealant. We offer top brands like Vitcas, Kos, and Envirograf for this purpose.

A pellet stove is a practical and flexible alternative to conventional wood burning stoves, especially in homes lacking chimneys. Pellet stoves can be vented through walls without requiring a chimney, making them an appealing choice for homeowners seeking efficient heating solutions.

While you can bypass this step and connect the Twin Wall flue directly to the outlet collar with an Adapter, this might eventually tarnish the finish of a stainless Twin Wall pipe or strip the coating from a black Twin Wall pipe.

Remember, hot gases naturally rise, so a straight vertical length at the beginning of the system is beneficial. The sooner gases encounter a bend, the harder it is for them to pass through without leaving soot deposits or falling back down the chimney. Exiting through the top outlet of the stove is ideal, but using a Single Wall 90° Tee Piece to exit the rear outlet is permissible if necessary.

Which Twin Wall Adapter Do You Require?

As much Single Wall pipe can be used from the stove as required (but should be kept to a minimum) but you must convert from this to Twin Wall insulated flue a minimum of 6” (150mm) prior to reaching the underside of your ceiling / roof or inside of your wall.

The crucial building regulation to consider at this point regards the internal diameter of your flue system. The minimum internal diameter for a flue system when you reach the Twin Wall section is 6” (150mm) and this is easily attained by selecting the correct Single to Twin Wall Adapter. It is a common misconception that a system increases when it converts from Single Wall to Twin Wall flue simply due to the change in the overall size of the pipe but this is incorrect. We are only concerned with the internal diameter of the system and so to maintain the same diameter throughout (i.e. 5” to 5”) you require a Single to Twin Wall Adapter and to increase the diameter (i.e. 4” to 5”, 5” to 6” etc) only then do you require an Increasing Single to Twin Wall Adapter.

The only exception to this rule is for DEFRA approved stoves. Due to the cleaner burning nature of these models, they alone are permitted to remain at 5” diameter for the entire flue system and still comply with Approved Document J of the Building Regulations.

Now your system has begun correctly and you have successfully made the conversion from Single Wall pipe to Twin Wall insulated, you must plan the route your flue will take; internal, external or a mixture of both.

How To Install a Wood Burning Stove Chimney Through a Wall (External)

A common mistake when installing a wood-burning stove chimney through a wall is running the flue pipe straight out from the back of the stove and horizontally through the wall. This is incorrect because a flue system should not have horizontal sections longer than 150mm or include 90° (right-angle) turns. Hot gases need to rise, and if they are forced to move horizontally, they lose heat, cause soot buildup, and hit the right-angle turn like a barrier, which can make them fall back down the system.

An alternative setup for homes without traditional chimney systems is to install a wood burning fireplace, which can be a practical solution for effective and safe use during power outages.

To comply with the building regulations, a 90° Tee Piece (or elbow) can only be used directly in the rear outlet of the stove and absolutely nowhere else in the system. All bends can be no greater than 45° to allow the gases to continue rising freely and use these sparingly as you are limited to a maximum of 4 turns per system.

There are 4 Twin Wall items necessary to safely pass your system through an external wall; 45° Wall Sleeve, two Finish Plates and a Fixed or Adjustable length of Twin Wall pipe, long enough to pass clear through the wall whilst rising at that crucial 45° angle. The Sleeve protects both the pipe and the material of the wall from the thermal expansion of the pipe and the Plates tidy everything up inside and out. This is only applicable for passing through standard, non-combustible cavity walls. Should the wall consist of combustible materials (i.e. a wooden structure, you must allow for a safe clearance all the way around the flue of 60mm although this does vary depending on the brand of Twin Wall used).

Now your Twin Wall system has successfully exited the property, we need to turn the system vertically which is easily achieved with (ideally) a 135° Tee Piece & removeable Cap or a 45° Elbow. The benefit of the Tee Piece & Cap is it allows essential access to the external run of flue for cleaning and draining of condensates and rain water. The 45° Elbow does not offer this access.

For the optimum draw on your stove and compliance with the building regulations, the overall length of your flue system must attain a minimum length of 4.5m from stove outlet to Rain Cap. This does not pose an issue for chimneys on two storey homes but must be considered for shorter installs such as conservatories and summer houses. Depending on the length of flue selected for running through the wall dictates how far outside the system will sit from the outer surface. Quite often, this is only 50-80mm between outer wall surface and the pipe for aesthetic purposes and use with the shortest (and cheapest) Wall Brackets.

There are two important points to consider when calculating the lengths of Twin Wall flue required to successfully (and legally) run the system up the outside of your property wall; 1) the overall height of the finished flue 2) do you need to negotiate around any obstacles such as windows or overhanging soffits? Remember building regulations only allow for a maximum of 4 turns in the entire chimney and 2 have been occupied already (before and after passing through the wall), therefore you can only use 2 more elbows to create an offset around an obstacle, usually the gutters / soffits. Should you find you have other obstructions then the chimney will need to be re-sited unfortunately.

The only form of support typically required for an external Twin Wall system are Adjustable or Fixed Wall Brackets secured to the outside wall of the property, securing the flue system every 2m at very most. These brackets can be either fixed at 50mm or adjustable such as 50-80mm, 80-130mm, 130-210mm (that’s distance from wall to pipe) or longer still but for long external runs of 4m or more, it is highly recommended to secure an Adjustable Base Support at the bottom of the system as an extra anchor for the long run of Twin Wall above in addition to the Brackets. For supporting a flue past the roof line, there is a selection of Guy Wires, Stays and Structural Locking bands

How High Must a Flue System Rise?

The final aspect of your flue system is ensuring you attain the necessary overall height and choice of suitable terminal…

For an external Twin Wall system rising up any wall other than a gable end, you must consider two building regulation requirements:

The flue must rise high enough to create a 2.3m horizontal clearance between the top of the last length of pipe and the surface of the roof

AND

It must rise at least 1000mm once passed the roof line / soffits / gutter (basically, the lowest section of the roof surface) OR as high as the ridge

If rising up a gable end, the above still applies but with one caveat:

If the system passes the edge of the roof within 600mm of the ridge itself, then the system must rise at least 600mm above that ridge

A couple of additional points that often occur concern adjacent buildings and dormer windows:

a) If the system looks due to terminate below a window in a pitched roof or within 2.3m horizontally of any openable window, sun light or dormer, then you must extend the system 1000mm above the window

b) Any adjacent buildings within 2.3m of your flue system must unfortunately also be cleared. The flue will have to rise at least 600mm above the highest point on the adjacent building

And finally, simply secure a Rain Cap, Anti-Wind Cowl or any choice of Twin Wall terminal available in your range of Twin Wall. These are fairly straight forward to understand but please bear in mind, no Rain Cap is water tight and Anti-Wind Cowls are only advised for longer systems that create a sufficient draw and are located in open or exposed areas such as hillsides, by open land or waterfronts.

How To Install a Wood Burning Stove Chimney Through a Roof (Internal)

A typical internal Twin Wall flue system starts identically to that of an external system from the stove collar to the Twin Wall Adapter, as outlined above. From this point however, we are not heading through a wall but rather travelling up through the floors of a building to eventually exit through the roof surface.

For each ceiling / joist you are to pass through, there are 3 essential components to purchase; 2 Ventilated Fire Stop Plates and a Joist Support. Sometimes sold as a ‘Fire Stop Spacer', Ventilated Fire Stop Plates must be secured into the ceiling or the floor whenever the system exits and/or enters a habited space. Basically, this boils down to requiring these plates everywhere except for the floor of the attic but even there it is recommended. And why ventilated plates? This is to ensure cool air can pass between the floors keeping the outer edges of the flue as cool as possible but still delaying the potential spread of fire. Solid Fire Stop Plates are for gas systems only. And as the name suggests, the Joist Support screws to each joist and forms a bracket for the system roughly every 2.5m. Therefore, in a typical two storey home, you shall require 4 Ventilated Fire Stop Plates and 2 Joist Supports.

No matter which type of system is being installed, any joints between pipes must be accessible and not buried within walls or joists and the Twin Wall must be boxed or caged in on the upper floors.

The most effective form of flue system is a vertical, internal chimney however, you do have up to 4 bends or turns allowed within the system should you need to negotiate around an obstacle along the way in the form of 45° Elbows (never 90°) and a Roof Support should be used on the rafters as a final form of support.

It is now time to pass the Twin Wall flue through the roof surface itself and there are three important stages to this:

Firstly, remember there is a safe clearance to combustible materials that must be maintained around all twin wall flue and so a 6” Twin Wall pipe will require a hole measuring approx. 320mm across (60mm clearance + 200mm outer diameter of pipe + 60mm clearance).

Secondly, selecting the correct Flashing for your roof is critical. The Flashing itself is a silicone or EPDM rubber cone that sits atop a base (traditionally lead but more likely aluminium these days) and can be cut back to tightly grip around the flue to provide a weather proof seal on the roof. However, Flashings do not need to be confusing as they basically fall into one of only two categories; either suitable for a tiled/slate roof or not. Flashings for tiled roofs have a large base which needs to be secured underneath the tiles whereas Flashings for every other roof type (flat, corrugated, wooden etc.) has a small base designed to be secured on top of the roof surface.

Thirdly, combine your Flashing with a Twin Wall Storm Collar to sit approx. 100mm above the Flashing as an extra layer of protection against the elements.

How High Must a Flue System Rise?

And the final aspect of your flue system is ensuring you attain the necessary overall height and choice of suitable terminal…

For an internal Twin Wall system rising up through the roof surface, you must consider all four of the following building regulation requirements:

The flue must rise high enough to create a 2.3m horizontal clearance between the top of the last length of pipe and the surface of the roof

AND…

It must rise at least 1000mm once through the surface of the roof

ALSO CONSIDER…

If the system passes through the roof surface within 600mm of the ridge itself, then the system must rise at least 600mm above that ridge
If the system looks due to terminate below a window in a pitched roof or within 2.3m horizontally of any openable window, sun light or dormer, then you must extend the system 1000mm above the window

Choosing the Right System

When it comes to installing a wood burning stove without a chimney, choosing the right system is crucial. A twin wall flue system is the most common solution, but it’s essential to consider the specific needs of your property and the type of stove you want to install. Here are some factors to consider:

The Size and Type of Stove: Different wood burning stoves have varying flue requirements. Ensure that the twin wall flue system you choose is compatible with your stove’s specifications. This includes matching the stove pipe diameter to the stove’s outlet to maintain a secure and efficient connection.
Location of the Stove: The room where you plan to install the stove plays a significant role in determining the flue system’s length and configuration. For rooms with low ceilings, a shorter flue system may be necessary, while high-ceilinged rooms might require a longer setup.
Type of Fuel: If you plan to burn wood, ensure the system is designed for wood burning. For those considering a pellet stove, opt for a system specifically designed for pellet burning to ensure optimal performance and safety.
Budget: Twin wall flue systems can vary widely in price. Set a budget that includes the cost of the stove, flue system, and installation. This will help you choose a system that fits within your financial constraints while meeting all safety and regulatory requirements.

By carefully considering these factors, you can select a twin wall flue system that ensures safe, efficient, and compliant operation of your wood burning stove.

Essential Components

A twin wall flue system is composed of several key components that work together to safely vent the smoke and gases from your wood burning stove. At the heart of this system is the stainless steel pipe wrapped in thick insulation, which is then encased by a second outer tube. This design ensures that the temperature inside the flue remains high enough to allow the fumes to rise and be expelled outside, while the outer surface stays cool enough to be safe. The system also includes a stove pipe, which connects the stove to the twin wall flue system. It’s crucial to ensure that the stove pipe diameter fits the stove’s outlet perfectly. Choosing a stove pipe that is compatible with your twin wall flue system is essential for maintaining a secure and efficient connection.

Installation Considerations

Installing a wood burning stove without a chimney requires careful consideration of several factors to ensure safe and efficient operation. Here are some key points to keep in mind:

Correct Flue Installation: The flue system must be installed correctly to ensure it functions safely and efficiently. This includes ensuring the flue is the correct size for the stove and is installed at the proper angle to facilitate the natural rise of hot gases.
Suitable Hearth: The stove must be installed on a suitable hearth, which should be at least 12mm thick and made of a non-combustible material. This provides a stable and safe base for the stove.
Compatible Stove Pipe: Ensure that the stove pipe is compatible with the twin wall flue system. The stove pipe diameter must fit the stove’s outlet perfectly to maintain a secure and efficient connection.
Compliance with Regulations: The installation must comply with twin flue chimney regulations. This includes ensuring the flue system is installed correctly and the stove is positioned according to safety guidelines. Adhering to these regulations is crucial for safe operation and to avoid potential legal issues.
Professional Consultation: It’s highly recommended to consult a professional installer. They can ensure that the installation is done correctly and safely, providing peace of mind and compliance with all relevant regulations.

Safety Precautions

Safety is paramount when installing and operating a wood burning stove without a chimney. Ensuring that the stove and flue system are installed correctly is the first step in preventing accidents. Regular maintenance of the flue system is crucial to keep it functioning properly and to prevent the buildup of soot and creosote, which can lead to chimney fires. Installing a CO detector in the same room as the stove is highly recommended, as it can alert you to the presence of dangerous carbon monoxide gas. Always follow the manufacturer’s instructions for both the stove and the flue system, and take necessary precautions to prevent fires. This includes keeping flammable materials away from the stove and ensuring that the stove door is securely closed when the stove is in use. Regularly check the system for any signs of wear or damage, and address any issues promptly to ensure safe operation.

Cost and Budgeting

The cost of installing a wood burning stove without a chimney can vary depending on several factors, including the type of stove and flue system, the complexity of the installation, and the location of the installation. Here are some estimated costs to consider:

Twin Wall Flue System: The cost of a twin wall flue system can range from £500 to £2,000, depending on the length and complexity of the system required for your installation.
Stove: The price of a wood burning stove can vary widely, typically ranging from £500 to £2,000, depending on the model, size, and features.
Installation: Professional installation costs can range from £500 to £2,000, depending on the complexity of the installation and the rates of the installer.
Total Cost: Considering the above factors, the total cost of installing a wood burning stove without a chimney can range from £1,500 to £6,000.

It’s essential to set a budget and choose a system that fits within it. Additionally, consider the long-term costs of owning a wood burning stove, including the cost of fuel and regular maintenance. By planning your budget carefully, you can ensure that your investment in a wood burning stove provides efficient and reliable heat for years to come.

Maintenance and Upkeep

Wood burning stoves require regular maintenance to ensure safe and efficient operation. Here are some essential maintenance tasks to keep in mind:

Regular Cleaning: Both the stove and the flue system must be cleaned regularly to prevent the buildup of soot and creosote, which can lead to chimney fires. Regular cleaning ensures efficient operation and prolongs the life of your stove and flue system.
Long Periods of Operation: Operating the stove for long periods helps prevent coking and ensures efficient heat transfer. Avoid short, intense fires that can lead to incomplete combustion and increased soot buildup.
Stove Pipe Inspection: Regularly inspect the stove pipe to ensure it is in good condition and properly installed. Look for any signs of wear, damage, or blockages that could affect the system’s performance.
Hearth Inspection: Ensure that the hearth remains in good condition and continues to provide a stable, non-combustible base for the stove. Regular inspections can help identify any issues that need to be addressed.
CO Detectors: Installing CO detectors in the same room as the stove is essential for safety. Regularly check and maintain these detectors to ensure they are functioning correctly and can alert you to the presence of dangerous carbon monoxide gas.

By following these maintenance tips, you can ensure that your wood burning stove operates safely and efficiently, providing reliable heat for your home. Regular upkeep not only enhances performance but also extends the lifespan of your stove and flue system.