Certified Flue Sets
We use double-walled, certified flue sets. This ensures your wall flue meets the standard and your stove's manual.
Wall Flue for Stove or Pellet Stove: Key Considerations
Written by Dries Nijs3 min readWall Flue for Stove or Pellet Stove: What to Consider
A wall flue must be double-walled, with a certified flue set, sufficient distance from combustible materials, and a water- and airtight finish. You go through the wall and climb outside up to above the roofline, with a T-piece with condensate cap at the bottom.
Safety means double-walled, at a distance, and high enough.
A wall flue for a stove must be double-walled, with a certified flue set, sufficient distance from combustible materials, and a water- and airtight finish. You go through the wall with the flue and then climb outside up to above the roofline. This ensures proper draft and a safe flue. Below, you'll find what to really consider for a stove wall flue.
This approach is often used for a pellet stove in an existing home. There is no free chimney, so the flue through the wall is the simplest, safest way out. However, the requirements remain strict, as you are dealing with hot flue gases close to the facade.
Why You Go Through the Wall and Then Up
You go through the wall and then climb vertically outside because a flue needs draft. Draft is created by the height difference and the temperature difference between the warm flue gases inside and the cooler air outside. A short, horizontal section does not provide this draft.
Therefore, the outside flue runs up to above the roofline. This way, the outlet is in a place where the smoke can disperse freely and not blow back to windows or roof surfaces. The exact height depends on your roof and the standard, so you should check this per situation.
Through the Wall or Through the Roof
A wall flue is only safe if the flue is double-walled, kept at a distance from combustible materials, and exits high enough outside.
Fireproof Installation
We maintain the correct distance from combustible materials. The flue through wood or insulation is finished fireproof.
Tailored Advice
You receive honest advice about the wall, height, and diameter. This way, you know in advance what your situation requires.
Step-by-Step Considerations
The order below keeps your wall flue safe and works well with the standard and the manual. Check these points before drilling or ordering parts.
Choose a certified, double-walled flue set that suits your stove and the wall, whether it's a wooden or insulated facade.
Maintain the prescribed distance to combustible materials, according to the standard and your stove's manual.
Place a T-piece with condensate cap at the bottom of the outside flue, so moisture can drain and you can inspect the flue.
Let the flue run up outside to above the roofline, so the height meets the standard and the draft is correct.
Finish the flue water- and airtight, on both the inside and outside of the wall.
Checklist for Your Wall Flue
Double-walled flue with a certified flue set.
Sufficient distance from wood, insulation, and other combustible parts.
T-piece with condensate cap at the bottom of the outside flue.
Outside flue up to above the roofline, with the correct height.
Water- and airtight finish around the wall flue.
Correct diameter, matching your stove and manual.
Fireproof Flue Through Wood or Insulation
For a wooden or insulated wall, the flue itself is the focal point. A certified flue set ensures the necessary distance between the hot flue and the combustible material. You finish the opening with non-combustible material, according to the manufacturer's instructions.
Cut the opening large enough and do not fill the space with regular insulation that can char. The correct distance and finish are in the flue set's manual and the standard. If in doubt, have this point checked by a professional.
Why Double-Walled and the Right Diameter Matter
A wall flue only works well with a double-walled, insulated flue. The insulation keeps the flue gases warm, improving draft and reducing condensation and creosote. The outer shell remains cooler, making the flue through the wall safer.
The difference between the types is explained in our article on single-walled or double-walled flue. Choose the right size based on what diameter stove pipe you need.
A too narrow flue restricts exhaust, a too wide flue cools the smoke too quickly. In both cases, draft decreases and the risk of pollution increases. Always follow the diameter from your pellet stove or wood stove manual.
With a pellet stove wall flue, condensation is an extra factor. Pellet stoves operate with lower flue gas temperatures, causing moisture to form in the flue more quickly. The T-piece with condensate cap at the bottom is therefore not a detail but an essential part of a flue through the wall.
Regulations in Belgium and the Netherlands
The exact heights and distances vary per situation, so always follow the standard, the manual, and your municipality. In Belgium, the NBN standards for flue gas evacuation are the guideline, in the Netherlands, you look at the Building Decree and local regulations.
If you're unsure between a solution along the facade or through the roof, read our article on flue through the roof or wall. Your insurer may also require a correct, certified installation after damage.
Keep in mind that the municipality may sometimes impose additional rules regarding the location of the outlet or the facade. For a shared wall or apartment, stricter conditions often apply. Check this in advance so you don't have to make adjustments later.
Want to be sure of a safe, standard-compliant wall flue for your stove or pellet stove? Request a quote or advice and we will review your situation with you.
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Frequently asked questions
Yes, a wall flue should be double-walled and insulated. The insulation keeps the flue gases warm, improving draft and reducing condensation. The cooler outer shell also makes the flue through the wall safer.
The outside flue should reach above the roofline to ensure proper draft and prevent smoke from blowing back. The exact height is determined by the standard and your stove's manual, so it varies per roof and situation.
A T-piece with condensate cap collects moisture that forms in the flue and allows it to drain at the bottom. You can also inspect and clean the flue from this point, which is especially important for a pellet stove.
Yes, but a certified flue set with extra distance from the wood is required. You must finish the opening fireproof and maintain the prescribed distance from combustible materials, according to the standard and manual.
